Merckx and Gomes introduce mycoheterotrophy, the ability of a plant to take up its carbon from a close fungal partner.

Gregor Christa introduces kleptoplasty - the process by which heterotrophs steal chloroplasts from algae and incorporate them into their cytosol.

Whiteman introduces mistletoes, above-ground parasitic plants.

Chen, Zhang et al. introduce the necrotrophic fungal plant pathogen Botrytis cinerea more commonly known as gray mold.

Ji et al. introduce vertical farming, a production-scale crop-growth system within an enclosed structure that maximizes space-use efficiency by growing plants vertically and precisely controls the plant environment.

Palmer introduces the specialized defensive symbionts known as acacia ants.

Djamei introduces the fungal pathogen (and culinary delicacy) Ustilago maydis.

Most of the world's ecosystems are dominated by plants, and preserving the natural and agricultural landscapes that we depend on therefore requires understanding plants and their interactions at local and global scales. This is challenging because plants' ways of perceiving each other and communicating with each other and with animals are so fundamentally different from the ways we animals communicate with, and manipulate, each other. The collection of articles in the present issue of Current Biology illustrates the progress being made in deciphering some of the processes and mechanisms involved in plant interactions at different scales. While the topic of interactions with plants is very broad, any overview will require covering chemical signals and their reception; mutualisms and symbioses; interactions with pathogens; and interactions in communities. Approaches taken in these fields range from molecular biology and physiology to ecology.

The first infectious agent to bear the name 'virus' was described in 1898: a plant pathogen called tobacco mosaic virus that infects a wide range of plants and results in a yellow mosaic of the leaves. Since then, the study of plant viruses has facilitated new discoveries in both virology and plant biology. Traditionally, research has focused on viruses that cause severe disease in plants used for human and animal food or recreation. However, closer inspection of the plant-associated virome is now revealing interactions that range from pathogenic to symbiotic. Although they are often studied in isolation, plant viruses are usually found as part of a broader community that includes other plant-associated microbes and pests. For example, biological vectors of plant viruses (arthropods, nematodes, fungi, and protists) can facilitate the transmission of viruses between plants in an intricate interaction. To enhance transmission, viruses can induce the plant to 'lure' the vector by modulating plant chemistry and defenses. Once delivered to a new host, viruses are dependent on specific proteins that modify the structural components of the cell to enable transport of viral proteins and genomic material. Links between antiviral plant defenses and key steps in virus movement and transmission are being revealed. Upon infection, a suite of antiviral responses is triggered, including the expression of resistance genes - a favored strategy to control plant viruses. In this primer, we discuss these features and more, highlighting the exciting world of plant-virus interactions.

Environmental factors such as light, water, minerals, temperature, and other organisms affect plant growth and development. Unlike animals, plants can't escape from unfavorable biotic and abiotic stresses. Thus, they evolved the ability to biosynthesize specific chemicals referred to as plant specialized metabolites in order to facilitate successful interactions with the surrounding environment, as well as with other organisms including plants, insects, microorganisms, and animals. While the exact number of plant specialized metabolites, historically called secondary metabolites, is currently unknown, it has been estimated to range from 200,000 to 1,000,000 compounds. In contrast to the species-, organ- and tissue-specific nature of plant specialized metabolites, primary metabolites are shared by all living organisms, are vital for growth, development and reproduction, and comprise only about 8,000 compounds. The biosynthesis and storage of plant specialized metabolites are developmentally and temporally regulated and depend on biotic and abiotic factors. Specific cell types, subcellular organelles, microcompartments, and/or anatomical structures are often devoted to producing and storing these compounds. The functions of many specialized metabolites are still not fully understood but are generally considered to be essential for the fitness and survival of plants, partially by interacting with other organisms in both mutualistic (for example, attraction of pollinators) and antagonistic (such as defense against herbivores and pathogens) ways. In this primer, we will focus on specialized-metabolite functions in plant defense interactions and on the genetic, molecular, and biochemical mechanisms leading to the structural diversity of specialized metabolites. Though less understood, we will also touch on the mode of action of specialized metabolites in plant defense.

An interview with Rachael Jack, who studies how the human face transmits social information.

Plant life defines the environments to which animals adapt and provides the basis of food webs. This was equally true for hunter-gatherer economies of ancestral humans, yet through the domestication of plants and the creation of agricultural ecologies based around them, human societies transformed vegetation and transported plant taxa into new geographical regions. These human-plant interactions ultimately co-evolved, increasing human population densities, technologies of farming, and the diversification of landraces and crop complexes. Research in archaeology on preserved plant remains (archaeobotany) and on the genomes of crops, including ancient genomes, has transformed our scientific understanding of the complex relationships between humans and plants that are entailed by domestication. Key realizations of recent research include the recognition that: the co-evolution of domesticates and cultures was protracted, the adaptations of plant populations were unintended results of human economies rather than intentional breeding, domestication took place in dozens of world regions involving different crops and cultures, and convergent evolution can be recognized among cropping types - such as among seed crops, tuber crops, and fruit trees. Seven general domestication pathways can be defined for plants. Lessons for the present-day include: the importance of diversity in the past; genetic diversity within species has the potential to erode over time, but also to be rescued through processes of integration; similarly, diversification within agricultural ecosystems has undergone processes of decline, including marginalised, lost and 'forgotten' crops, as well as processes of renewal resulting from trade and human mobility that brought varied crops and varieties together.

The flower is arguably the centrepiece of angiosperm evolution. Its primary function is to secure pollination - the transfer of pollen from the anther (male) to the stigma (female). As plants are sessile organisms, the extraordinary diversity of flowers in large part reflects countless alternative evolutionary solutions to achieve this critical step in the flowering plant life cycle. The majority of flowering plants, some 87% by one estimate, depend on animals for pollination, with most of these paying for the service of pollination via food rewards of nectar or pollen. As in human economic systems, however, some cheating and deception occurs, with the pollination strategy of sexual deception being one such example.

There is a growing realization that ecological interactions take place at many scales, from acorns to forests, and that formerly overlooked community members, particularly microbes, can play outsized ecological roles. Beyond their primary function as the reproductive organs of angiosperms, flowers constitute resource-rich, ephemeral habitats teeming with flower-loving symbionts, or 'anthophiles'. The physical, chemical, and structural properties of flowers combine to create a habitat filter, selectively determining which anthophiles can reside there, and how, and when they interact. The microhabitats within flowers can provide shelter from predators or inclement weather, places to eat, sleep, thermoregulate, hunt, mate or reproduce. In turn, floral microhabitats contain the full range of mutualists, antagonists and apparent commensals, whose complex interactions impact how flowers look and smell, how profitable they are to foraging pollinators, and how selection feeds back upon the traits shaping those interactions. Recent studies suggest coevolutionary paths by which floral symbionts might be co-opted as mutualists and provide compelling examples in which ambush predators or florivores are recruited as floral allies. Unbiased studies that include the full roster of floral symbionts are likely to reveal novel links and additional nuance in the rich ecological communities hidden within flowers.

Flowers are the most commonly seen colourful elements of the natural world, and in this primer we explain the evolution of their spectacular range of colours. To understand flower colour, we first explain what colour is and how a flower can have different colours in the eyes of different observers. We briefly introduce the molecular and biochemical basis of flower colour, which is primarily based on well-characterised pigment synthesis pathways. We then consider the evolution of flower colour over four timescales - its origin and deep evolution, its macroevolution, its microevolution and finally, the recent effects of human behaviour on flower colour and its evolution. Because flower colour is so evolutionarily labile, and at the same time so striking to the human eye, it is an exciting subject for current and future research efforts.

Salvioli di Fossalunga and Bonfante introduce how arbuscular mycorrhizal fungi can be applied as biofertilizers.

Large herbivores play unique ecological roles and are disproportionately imperiled by human activity. As many wild populations dwindle towards extinction, and as interest grows in restoring lost biodiversity, research on large herbivores and their ecological impacts has intensified. Yet, results are often conflicting or contingent on local conditions, and new findings have challenged conventional wisdom, making it hard to discern general principles. Here, we review what is known about the ecosystem impacts of large herbivores globally, identify key uncertainties, and suggest priorities to guide research. Many findings are generalizable across ecosystems: large herbivores consistently exert top-down control of plant demography, species composition, and biomass, thereby suppressing fires and the abundance of smaller animals. Other general patterns do not have clearly defined impacts: large herbivores respond to predation risk but the strength of trophic cascades is variable; large herbivores move vast quantities of seeds and nutrients but with poorly understood effects on vegetation and biogeochemistry. Questions of the greatest relevance for conservation and management are among the least certain, including effects on carbon storage and other ecosystem functions and the ability to predict outcomes of extinctions and reintroductions. A unifying theme is the role of body size in regulating ecological impact. Small herbivores cannot fully substitute for large ones, and large-herbivore species are not functionally redundant - losing any, especially the largest, will alter net impact, helping to explain why livestock are poor surrogates for wild species. We advocate leveraging a broad spectrum of techniques to mechanistically explain how large-herbivore traits and environmental context interactively govern the ecological impacts of these animals.

For more than 400 million years, mycorrhizal fungi and plants have formed partnerships that are crucial to the emergence and functioning of global ecosystems. The importance of these symbiotic fungi for plant nutrition is well established. However, the role of mycorrhizal fungi in transporting carbon into soil systems on a global scale remains under-explored. This is surprising given that ∼75% of terrestrial carbon is stored belowground and mycorrhizal fungi are stationed at a key entry point of carbon into soil food webs. Here, we analyze nearly 200 datasets to provide the first global quantitative estimates of carbon allocation from plants to the mycelium of mycorrhizal fungi. We estimate that global plant communities allocate 3.93 Gt CO2e per year to arbuscular mycorrhizal fungi, 9.07 Gt CO2e per year to ectomycorrhizal fungi, and 0.12 Gt CO2e per year to ericoid mycorrhizal fungi. Based on this estimate, 13.12 Gt of CO2e fixed by terrestrial plants is, at least temporarily, allocated to the underground mycelium of mycorrhizal fungi per year, equating to ∼36% of current annual CO2 emissions from fossil fuels. We explore the mechanisms by which mycorrhizal fungi affect soil carbon pools and identify approaches to increase our understanding of global carbon fluxes via plant-fungal pathways. Our estimates, although based on the best available evidence, are imperfect and should be interpreted with caution. Nonetheless, our estimations are conservative, and we argue that this work confirms the significant contribution made by mycorrhizal associations to global carbon dynamics. Our findings should motivate their inclusion both within global climate and carbon cycling models, and within conservation policy and practice.

Carnivorous plants often spark broad interest due to their specialized adaptations for trapping and consuming animals. These notable organisms not only fix carbon through photosynthesis, but they also obtain essential nutrients such as nitrogen and phosphate from their captured prey. In typical angiosperms, interactions with animals are usually confined to such processes as pollination and herbivory, but another layer of complexity in these interactions is added for carnivorous plants. Here, we introduce carnivorous plants and their associated organisms - ranging from their prey to their symbionts - and highlight biotic interactions beyond carnivory to discuss how the 'default' interactions typical for flowering plants have changed in the case of the carnivorous plants (Figure 1).

Volatile organic compounds (VOCs) in general and herbivory-induced plant volatiles (HIPVs) in particular are increasingly understood as major mediators of information transfer between plant tissues. Recent findings have moved the field of plant communication closer to a detailed understanding of how plants emit and perceive VOCs and seem to converge on a model that juxtaposes perception and emission mechanisms. These new mechanistic insights help to explain how plants can integrate different types of information and how environmental noise can affect the transmission of information. At the same time, ever-new functions of VOC-mediated plant-plant interactions are being revealed. Chemical information transfer between plants is now known to fundamentally affect plant organismal interactions and, additionally, population, community, and ecosystem dynamics. One of the most exciting new developments places plant-plant interactions along a behavioral continuum with an eavesdropping strategy at one end and mutually beneficial information-sharing among plants within a population at the other. Most importantly and based on recent findings as well as theoretical models, plant populations can be predicted to evolve different communication strategies depending on their interaction environment. We use recent studies from ecological model systems to illustrate this context dependency of plant communication. Moreover, we review recent key findings about the mechanisms and functions of HIPV-mediated information transfer and suggest conceptual links, such as to information theory and behavioral game theory, as valuable tools for a deeper understanding of how plant-plant communication affects ecological and evolutionary dynamics.

Plants associate with nitrogen-fixing bacteria to secure nitrogen, which is generally the most limiting nutrient for plant growth. Endosymbiotic nitrogen-fixing associations are widespread among diverse plant lineages, ranging from microalgae to angiosperms, and are primarily one of three types: cyanobacterial, actinorhizal or rhizobial. The large overlap in the signaling pathways and infection components of arbuscular mycorrhizal, actinorhizal and rhizobial symbioses reflects their evolutionary relatedness. These beneficial associations are influenced by environmental factors and other microorganisms in the rhizosphere. In this review, we summarize the diversity of nitrogen-fixing symbioses, key signal transduction pathways and colonization mechanisms relevant to such interactions, and compare and contrast these interactions with arbuscular mycorrhizal associations from an evolutionary standpoint. Additionally, we highlight recent studies on environmental factors regulating nitrogen-fixing symbioses to provide insights into the adaptation of symbiotic plants to complex environments.

Self-incompatibility (SI) plays a pivotal role in whether self-pollen is accepted or rejected. Most SI systems employ two tightly linked loci encoding highly polymorphic pollen (male) and pistil (female) S-determinants that control whether self-pollination is successful or not. In recent years our knowledge of the signalling networks and cellular mechanisms involved has improved considerably, providing an important contribution to our understanding of the diverse mechanisms used by plant cells to recognise each other and elicit responses. Here, we compare and contrast two important SI systems employed in the Brassicaceae and Papaveraceae. Both use 'self-recognition' systems, but their genetic control and S-determinants are quite different. We describe the current knowledge about the receptors and ligands, and the downstream signals and responses utilized to prevent self-seed set. What emerges is a common theme involving the initiation of destructive pathways that block the key processes that are required for compatible pollen-pistil interactions.

Two concurrent trends are contributing towards a much broader view of forest conservation. First, the appreciation of the role of forests as a nature-based climate solution has grown rapidly, particularly among governments and the private sector. Second, the spatiotemporal resolution of forest mapping and the ease of tracking forest changes have dramatically improved. As a result, who does and who pays for forest conservation is changing: sectors and people previously considered separate from forest conservation now play an important role and need to be held accountable and motivated or forced to conserve forests. This change requires, and has stimulated, a broader range of forest conservation solutions. The need to assess the outcomes of conservation interventions has motivated the development and application of sophisticated econometric analyses, enabled by high resolution satellite data. At the same time, the focus on climate, together with the nature of available data and evaluation methods, has worked against a more comprehensive view of forest conservation. Instead, it has encouraged a focus on trees as carbon stores, often leaving out other important goals of forest conservation, such as biodiversity and human wellbeing. Even though both are intrinsically connected to climate outcomes, these areas have not kept pace with the scale and diversification of forest conservation. Finding synergies between these 'co-benefits', which play out on a local scale, with the carbon objective, related to the global amount of forests, is a major challenge and area for future advances in forest conservation.

Plant diseases are strongly influenced by host biodiversity, spatial structure, and abiotic conditions. All of these are undergoing rapid change, as the climate is warming, habitats are being lost, and nitrogen deposition is changing nutrient dynamics of ecosystems with ensuing consequences for biodiversity. Here, I review examples of plant-pathogen associations to demonstrate how our ability to understand, model and predict disease dynamics is becoming increasingly difficult, as both plant and pathogen populations and communities are undergoing extensive change. The extent of this change is influenced via both direct and combined effects of global change drivers, and especially the latter are still poorly understood. Change at one trophic level is expected to drive change also at the other, and hence feedback loops between plants and their pathogens are expected to drive changes in disease risk both through ecological as well as evolutionary mechanisms. Many of the examples discussed here demonstrate an increase in disease risk as a result of ongoing change, suggesting that unless we successfully mitigate global environmental change, plant disease is going to become an increasingly heavy burden on our societies with far-reaching consequences for food security and functioning of ecosystems.

Lichens are a diverse group of organisms. They are both commonly observed but also mysterious. It has long been known that lichens are composite symbiotic associations of at least one fungus and an algal or cyanobacterial partner, but recent evidence suggests that they may be much more complex. We now know that there can be many constituent microorganisms in a lichen, organized into reproducible patterns that suggest a sophisticated communication and interplay between symbionts. We feel the time is right for a more concerted effort to understand lichen biology. Rapid advances in comparative genomics and metatranscriptomic approaches, coupled with recent breakthroughs in gene functional studies, suggest that lichens may now be more tractable to detailed analysis. Here we set out some of the big questions in lichen biology, and we speculate about the types of gene functions that may be critical to their development, as well as the molecular events that may lead to initial lichen formation. We define both the challenges and opportunities in lichen biology and offer a call to arms to study this remarkable group of organisms.

General anesthesia (GA) is an unconscious state produced by anesthetic drugs, which act on neurons to cause overall suppression of neuronal activity in the brain. Recent studies have revealed that GA also substantially enhances the dynamics of microglia, the primary brain immune cells, with increased process motility and territory surveillance. However, whether microglia are actively involved in GA modulation remains unknown. Here, we report a previously unrecognized role for microglia engaging in multiple GA processes. We found that microglial ablation reduced the sensitivity of mice to anesthetics and substantially shortened duration of loss of righting reflex (LORR) or unconsciousness induced by multiple anesthetics, thereby promoting earlier emergence from GA. Microglial repopulation restored the regular anesthetic recovery, and chemogenetic activation of microglia prolonged the duration of LORR. In addition, anesthesia-accompanying analgesia and hypothermia were also attenuated after microglial depletion. Single-cell RNA sequencing analyses showed that anesthesia prominently affected the transcriptional levels of chemotaxis and migration-related genes in microglia. By pharmacologically targeting different microglial motility pathways, we found that blocking P2Y12 receptor (P2Y12R) reduced the duration of LORR of mice. Moreover, genetic ablation of P2Y12R in microglia also promoted quicker recovery in mice from anesthesia, verifying the importance of microglial P2Y12R in anesthetic regulation. Our work presents the first evidence that microglia actively participate in multiple processes of GA through P2Y12R-mediated signaling and expands the non-immune roles of microglia in the brain.

Forest ecosystems all over the world are facing a growing threat from plant-disease outbreaks. As pollution, climate change, and global pathogen movement intensify, so too do the impacts of forest pathogens. In this essay, we examine a case study of the New Zealand kauri tree (Agathis australis) and its oomycetepathogen, Phytophthora agathidicida. We focus on the interactions between the host, pathogen, and environment - the building blocks of the 'disease triangle', a framework used by plant pathologists to understand and manage diseases. We delve into why this framework is more challenging to apply to trees than crops, taking into account the differences in reproductive time, level of domestication, and surrounding biodiversity between the host (a long-lived native tree species) and typical crop plants. We also address the difficulties in managing Phytophthora diseases compared to fungal or bacterial pathogens. Furthermore, we explore the complexities of the environmental aspect of the disease triangle. In forest ecosystems, the environment is particularly complex, encompassing diverse macro- and microbiotic influences, forest fragmentation, land use, and climate change. By exploring these complexities, we emphasize the importance of targeting multiple components of the disease triangle simultaneously to make effective management gains. Finally, we highlight the invaluable contribution of indigenous knowledge systems in bringing a holistic approach to managing forest pathogens in Aotearoa New Zealand and beyond.

Interactions among organisms in natural ecosystems are the foundational underpinnings of nearly all ecological studies. It has never been more important to increase our awareness of how these interactions are altered by human activity, threatening biodiversity and disrupting ecosystem functioning. Much of the historic focus of species conservation has been the preservation of endangered and endemic species at risk from hunting, over-exploitation, and habitat destruction. However, there is increasing evidence that differences between plants and their attacking organisms in the speed and direction of physiological, demographic, and genetic (adaptation) responses to global change are having devastating consequences, resulting in large-scale losses of dominant or abundant plant species, particularly in forest ecosystems. From the elimination in the wild of the American chestnut to the extensive regional damage caused by insect outbreaks in temperate forest ecosystems, these losses of dominant species change the ecological landscape and functioning, and represent important threats to biodiversity at all scales. Introductions due to human activity, range shifts due to climate change, and their combination are the principal drivers behind these profound ecosystem changes. In this Review, we argue that there is an urgent need to increase our recognition and hone our predictive power for how these imbalances may occur. Moreover, we should seek to minimize the consequences of these imbalances in order to ensure the preservation of the structure, function and biodiversity of entire ecosystems, not just rare or highly endangered species.

The olfactory system uses hundreds of odorant receptors (ORs), the largest group of the G-protein-coupled receptor (GPCR) superfamily, to detect a vast array of odorants. Each OR is activated by specific odorous ligands, and like other GPCRs, antagonism can block activation of ORs. Recent studies suggest that odorant antagonisms in mixtures influence olfactory neuron activities, but it is unclear how this affects perception of odor mixtures. In this study, we identified a set of human ORs activated by methanethiol and hydrogen sulfide, two potent volatile sulfur malodors, through large-scale heterologous expression. Screening odorants that block OR activation in heterologous cells identified a set of antagonists, including β-ionone. Sensory evaluation in humans revealed that β-ionone reduced the odor intensity and unpleasantness of methanethiol. Additionally, suppression was not observed when methanethiol and β-ionone were introduced simultaneously to different nostrils. Our study supports the hypothesis that odor sensation is altered through antagonistic interactions at the OR level.

The circuitry underlying the detection of visual motion in Drosophila melanogaster is one of the best studied networks in neuroscience. Lately, electron microscopy reconstructions, algorithmic models, and functional studies have proposed a common motif for the cellular circuitry of an elementary motion detector based on both supralinear enhancement for preferred direction and sublinear suppression for null-direction motion. In T5 cells, however, all columnar input neurons (Tm1, Tm2, Tm4, and Tm9) are excitatory. So, how is null-direction suppression realized there? Using two-photon calcium imaging in combination with thermogenetics, optogenetics, apoptotics, and pharmacology, we discovered that it is via CT1, the GABAergic large-field amacrine cell, where the different processes have previously been shown to act in an electrically isolated way. Within each column, CT1 receives excitatory input from Tm9 and Tm1 and provides the sign-inverted, now inhibitory input signal onto T5. Ablating CT1 or knocking down GABA-receptor subunit Rdl significantly broadened the directional tuning of T5 cells. It thus appears that the signal of Tm1 and Tm9 is used both as an excitatory input for preferred direction enhancement and, through a sign inversion within the Tm1/Tm9-CT1 microcircuit, as an inhibitory input for null-direction suppression.

The development of plant roots is subject to control by light. Here, we show that, similar to monotonous root elongation, the periodic induction of lateral roots (LRs) depends on the activation by light of photomorphogenic and photosynthetic photoreceptors in the shoot in a hierarchical order. The prevailing belief is that the plant hormone auxin serves as a mobile signal transmitter, responsible for interorgan communication, including light-controlled shoot-to-root connections. Alternatively, it has been proposed that the transcription factor HY5 assumes the role as a mobile shoot-to-root signal transmitter. Here, we provide evidence that photosynthetic sucrose produced in the shoot acts as the long-distance signal carrier regulating the local, tryptophan-based biosynthesis of auxin in the LR generation zone of the primary root tip, where the LR clock controls the pace of LR initiation in an auxin-tunable manner. Synchronization of LR formation with primary root elongation allows the adjustment of overall root growth to the photosynthetic performance of the shoot and the maintenance of a constant LR density during light-dark changes in a variable light environment.

The ability to group abstract continuous magnitudes into meaningful categories is cognitively demanding but key to intelligent behavior. To explore its neuronal mechanisms, we trained carrion crows to categorize lines of variable lengths into arbitrary "short" and "long" categories. Single-neuron activity in the nidopallium caudolaterale (NCL) of behaving crows reflected the learned length categories of visual stimuli. The length categories could be reliably decoded from neuronal population activity to predict the crows' conceptual decisions. NCL activity changed with learning when a crow was retrained with the same stimuli assigned to more categories with new boundaries ("short", "medium," and "long"). Categorical neuronal representations emerged dynamically so that sensory length information at the beginning of the trial was transformed into behaviorally relevant categorical representations shortly before the crows' decision making. Our data show malleable categorization capabilities for abstract spatial magnitudes mediated by the flexible networks of the crow NCL.

Genome editing (GE) technologies allow rapid trait manipulation in crop plants. Disease resistance is one of the best test cases for this technology because it is usually monogenic and under constant challenge by rapidly evolving pathogens. Classical methods suffer from severe bottlenecks in discovery of new resistance (R) genes and their incorporation into elite varieties, largely because they are identified in landraces and species with limited sexual compatibility, and may last only a few years before losing effectiveness. Most plant R genes encode receptors located externally on the plasma membrane (receptor proteins and receptor kinases) or internally as NOD-like receptors (NLR). Both have well defined molecular interactions with activating pathogen ligands which are virulence proteins known as effectors. As structural data for R-effector interactions accumulate, promising strategies for rational manipulation of binding specificities are emerging. This offers the potential to change elite varieties directly rather than through 10-20 years of crossing. Successful application of GE is already evident in mutation of susceptibility (S) genes required for infection. GE is in its infancy with only four modified organisms grown currently in the US. The Anglosphere and Japan seem more open to deployment of these technologies, with the European Union, Switzerland and New Zealand being notably more conservative. Consumers are not well informed on the differences between GE and classical genetic modification (GM). The possibility that minor GE changes will not be regulated as GM offers the hope that current bottlenecks to resistance breeding can be eased.

Plant-predator mutualisms have been widely described in nature.1,2 How plants fine-tune their mutualistic interactions with the predators they recruit remains poorly understood. In the wild potato (Solanum kurtzianum), predatory mites, Neoseiulus californicus, are recruited to flowers of undamaged plants but rapidly move downward when the herbivorous mites, Tetranychus urticae, damage leaves. This "up-down" movement within the plant corresponds to the shift of N. californicus from palynivory to carnivory, as they change from feeding on pollen to herbivores when moving between different plant organs. This up-down movement of N. californicus is mediated by the organ-specific emissions of volatile organic compounds (VOCs) in flowers and herbivory-elicited leaves. Experiments with exogenous applications, biosynthetic inhibitors, and transient RNAi revealed that salicylic acid and jasmonic acid signaling in flowers and leaves mediates both the changes in VOC emissions and the up-down movement of N. californicus. This alternating communication between flowers and leaves mediated by organ-specific VOC emissions was also found in a cultivated variety of potato, suggesting the agronomic potential of using flowers as reservoirs of natural enemies in the control of potato pests.

Neuronal wiring diagrams reconstructed by electron microscopy1,2,3,4,5 pose new questions about the organization of nervous systems following the time-honored tradition of cross-species comparisons.6,7 The C. elegans connectome has been conceptualized as a sensorimotor circuit that is approximately feedforward,8,9,10,11 starting from sensory neurons proceeding to interneurons and ending with motor neurons. Overrepresentation of a 3-cell motif often known as the "feedforward loop" has provided further evidence for feedforwardness.10,12 Here, we contrast with another sensorimotor wiring diagram that was recently reconstructed from a larval zebrafish brainstem.13 We show that the 3-cycle, another 3-cell motif, is highly overrepresented in the oculomotor module of this wiring diagram. This is a first for any neuronal wiring diagram reconstructed by electron microscopy, whether invertebrate12,14 or mammalian.15,16,17 The 3-cycle of cells is "aligned" with a 3-cycle of neuronal groups in a stochastic block model (SBM)18 of the oculomotor module. However, the cellular cycles exhibit more specificity than can be explained by the group cycles-recurrence to the same neuron is surprisingly common. Cyclic structure could be relevant for theories of oculomotor function that depend on recurrent connectivity. The cyclic structure coexists with the classic vestibulo-ocular reflex arc for horizontal eye movements,19 and could be relevant for recurrent network models of temporal integration by the oculomotor system.20,21.

Drosophila compound eye morphogenesis transforms a simple epithelium into an approximate hollow hemisphere comprised of ∼700 ommatidia, packed as tapering hexagonal prisms between a rigid external array of cuticular lenses and a parallel, rigid internal floor, the fenestrated membrane (FM). Critical to vision, photosensory rhabdomeres are sprung between these two surfaces, grading their length and shape accurately across the eye and aligning them to the optical axis. Using fluorescently tagged collagen and laminin, we show that that the FM assembles sequentially, emerging in the larval eye disc in the wake of the morphogenetic furrow as the original collagen-containing basement membrane (BM) separates from the epithelial floor and is replaced by a new, laminin-rich BM, which advances around axon bundles of newly differentiated photoreceptors as they exit the retina, forming fenestrae in this new, laminin-rich BM. In mid-pupal development, the interommatidial cells (IOCs) autonomously deposit collagen at fenestrae, forming rigid, tension-resisting grommets. In turn, stress fibers assemble in the IOC basal endfeet, where they contact grommets at anchorages mediated by integrin linked kinase (ILK). The hexagonal network of IOC endfeet tiling the retinal floor couples nearest-neighbor grommets into a supracellular tri-axial tension network. Late in pupal development, IOC stress fiber contraction folds pliable BM into a hexagonal grid of collagen-stiffened ridges, concomitantly decreasing the area of convex FM and applying essential morphogenetic longitudinal tension to rapidly growing rhabdomeres. Together, our results reveal an orderly program of sequential assembly and activation of a supramolecular tensile network that governs Drosophila retinal morphogenesis.

Harmful algal blooms of the toxic haptophyte Prymnesium parvum are a recurrent problem in many inland and estuarine waters around the world. Strains of P. parvum vary in the toxins they produce and in other physiological traits associated with harmful algal blooms, but the genetic basis for this variation is unknown. To investigate genome diversity in this morphospecies, we generated genome assemblies for 15 phylogenetically and geographically diverse strains of P. parvum, including Hi-C guided, near-chromosome-level assemblies for two strains. Comparative analysis revealed considerable DNA content variation between strains, ranging from 115 to 845 Mbp. Strains included haploids, diploids, and polyploids, but not all differences in DNA content were due to variation in genome copy number. Haploid genome size between strains of different chemotypes differed by as much as 243 Mbp. Syntenic and phylogenetic analyses indicate that UTEX 2797, a common laboratory strain from Texas, is a hybrid that retains two phylogenetically distinct haplotypes. Investigation of gene families variably present across the strains identified several functional categories associated with metabolic and genome size variation in P. parvum, including genes for the biosynthesis of toxic metabolites and proliferation of transposable elements. Together, our results indicate that P. parvum comprises multiple cryptic species. These genomes provide a robust phylogenetic and genomic framework for investigations into the eco-physiological consequences of the intra- and inter-specific genetic variation present in P. parvum and demonstrate the need for similar resources for other harmful algal-bloom-forming morphospecies.

The 17th-century colonization of North America brought thousands of Europeans to Indigenous lands in the Delaware region, which comprises the eastern boundary of the Chesapeake Bay in what is now the Mid-Atlantic region of the United States.1 The demographic features of these initial colonial migrations are not uniformly characterized, with Europeans and European-Americans migrating to the Delaware area from other countries and neighboring colonies as single persons or in family units of free persons, indentured servants, or tenant farmers.2 European colonizers also instituted a system of racialized slavery through which they forcibly transported thousands of Africans to the Chesapeake region. Historical information about African-descended individuals in the Delaware region is limited, with a population estimate of less than 500 persons by 1700 CE.3,4 To shed light on the population histories of this period, we analyzed low-coverage genomes of 11 individuals from the Avery's Rest archaeological site (circa 1675-1725 CE), located in Delaware. Previous osteological and mitochondrial DNA (mtDNA) sequence analyses showed a southern group of eight individuals of European maternal descent, buried 15-20 feet from a northern group of three individuals of African maternal descent.5 Autosomal results further illuminate genomic similarities to Northwestern European reference populations or West and West-Central African reference populations, respectively. We also identify three generations of maternal kin of European ancestry and a paternal parent-offspring relationship between an adult and child of African ancestry. These findings expand our understanding of the origins and familial relationships in late 17th and early 18th century North America.

Extensive research across fields has repeatedly confirmed that early-life adversity (ELA) is a major selective force for many taxa, in part via its ties to adult health and longevity.1,2,3 Negative effects of ELA on adult outcomes have been documented in a wide range of species, from fish to birds to humans.4 We used 55 years of long-term data collected on 253 wild mountain gorillas to examine the effects of six putative sources of ELA on survival, both individually and cumulatively. Although cumulative ELA was associated with high mortality in early life, we found no evidence that it had detrimental consequences for survival later in life. Experiencing three or more forms of ELA was associated with greater longevity, with a 70% reduction in the risk of death across adulthood, driven specifically by greater longevity in males. Although this higher survival in later life is likely a consequence of sex-specific viability selection5 during early life due to the immediate mortality consequences of adverse experiences, patterns in our data also suggest that gorillas have significant resilience to ELA. Our findings demonstrate that the detrimental consequences of ELA on later life survival are not universal, and indeed largely absent in one of humans' closest living relatives. This raises important questions about the biological roots of sensitivity to early experiences and the protective mechanisms that contribute to resiliency in gorillas, which could be critical for understanding how best to encourage similar resiliency to early-life shocks in humans.

Mechanosensory feedback of the internal reproductive state drives decisions about when and where to reproduce.1 For instance, stretch in the Drosophila reproductive tract produced by artificial distention or from accumulated eggs regulates the attraction to acetic acid to ensure optimal oviposition.2 How such mechanosensory feedback modulates neural circuits to coordinate reproductive behaviors is incompletely understood. We previously identified a stretch-dependent homeostat that regulates egg laying in Caenorhabditis elegans. Sterilized animals lacking eggs show reduced Ca2+ transient activity in the presynaptic HSN command motoneurons that drive egg-laying behavior, while animals forced to accumulate extra eggs show dramatically increased circuit activity that restores egg laying.3 Interestingly, genetic ablation or electrical silencing of the HSNs delays, but does not abolish, the onset of egg laying,3,4,5 with animals recovering vulval muscle Ca2+ transient activity upon egg accumulation.6 Using an acute gonad microinjection technique to mimic changes in pressure and stretch resulting from germline activity and egg accumulation, we find that injection rapidly stimulates Ca2+ activity in both neurons and muscles of the egg-laying circuit. Injection-induced vulval muscle Ca2+ activity requires L-type Ca2+ channels but is independent of presynaptic input. Conversely, injection-induced neural activity is disrupted in mutants lacking the vulval muscles, suggesting "bottom-up" feedback from muscles to neurons. Direct mechanical prodding activates the vulval muscles, suggesting that they are the proximal targets of the stretch-dependent stimulus. Our results show that egg-laying behavior in C. elegans is regulated by a stretch-dependent homeostat that scales postsynaptic muscle responses with egg accumulation in the uterus.

Organization of protein sequences into domain families is a foundation for cataloging and investigating protein functions. However, long-standing strategies based on primary amino acid sequences are blind to the possibility that proteins with dissimilar sequences could have comparable tertiary structures. Building on our recent findings that in silico structural predictions of BEN family DNA-binding domains closely resemble their experimentally determined crystal structures, we exploited the AlphaFold2 database for comprehensive identification of BEN domains. Indeed, we identified numerous novel BEN domains, including members of new subfamilies. For example, while no BEN domain factors had previously been annotated in C. elegans, this species actually encodes multiple BEN proteins. These include key developmental timing genes of orphan domain status, sel-7 and lin-14, the latter being the central target of the founding miRNA lin-4. We also reveal that the domain of unknown function 4806 (DUF4806), which is widely distributed across metazoans, is structurally similar to BEN and comprises a new subtype. Surprisingly, we find that BEN domains resemble both metazoan and non-metazoan homeodomains in 3D conformation and preserve characteristic residues, indicating that despite their inability to be aligned by conventional methods, these DNA-binding modules are probably evolutionarily related. Finally, we broaden the application of structural homology searches by revealing novel human members of DUF3504, which exists on diverse proteins with presumed or known nuclear functions. Overall, our work strongly expands this recently identified family of transcription factors and illustrates the value of 3D structural predictions to annotate protein domains and interpret their functions.

One of the biggest planetary challenges is the accelerating loss of biodiversity threatening ecosystem functioning on a global scale. The WWF Living Planet Report (https://livingplanet.panda.org/) estimates a 69% decline in populations since 1970. The Convention on Biological Diversity and related international treaties ask countries to monitor shifts in community composition and assess rates of species decline to quantify extant biodiversity relative to global targets1. However, quantifying biodiversity is a challenge, and monitoring continual change is impossible at almost any scale due to a lack of standardized data and indicators2,3. A common problem is that the required infrastructure for such global monitoring does not exist. Here, we challenge this notion by analysing environmental DNA (eDNA) captured along with particulate matter by routine ambient air quality monitoring stations in the UK. In our samples, we identified eDNA from >180 vertebrate, arthropod, plant and fungal taxa representative of local biodiversity. We contend that air monitoring networks are in fact gathering eDNA data reflecting local biodiversity on a continental scale, as a result of their routine function. In some regions, air quality samples are stored for decades, presenting the potential for high resolution biodiversity time series. With minimal modification of current protocols, this material provides the best opportunity to date for detailed monitoring of terrestrial biodiversity using an existing, replicated transnational design and it is already in operation.

Despite a remarkable diversity of lifestyles, bacterial replication has only been investigated in a few model species. In bacteria that do not rely on canonical binary division for proliferation, the coordination of major cellular processes is still largely mysterious. Moreover, the dynamics of bacterial growth and division remain unexplored within spatially confined niches where nutrients are limited. This includes the life cycle of the model endobiotic predatory bacterium Bdellovibrio bacteriovorus, which grows by filamentation within its prey and produces a variable number of daughter cells. Here, we examined the impact of the micro-compartment in which predators replicate (i.e., the prey bacterium) on their cell-cycle progression at the single-cell level. Using Escherichia coli with genetically encoded size differences, we show that the duration of the predator cell cycle scales with prey size. Consequently, prey size determines predator offspring numbers. We found that individual predators elongate exponentially, with a growth rate determined by the nutritional quality of the prey, irrespective of prey size. However, the size of newborn predator cells is remarkably stable across prey nutritional content and size variations. Tuning the predatory cell cycle by modulating prey dimensions also allowed us to reveal invariable temporal connections between key cellular processes. Altogether, our data imply adaptability and robustness shaping the enclosed cell-cycle progression of B. bacteriovorus, which might contribute to optimal exploitation of the finite resources and space in their prey. This study extends the characterization of cell cycle control strategies and growth patterns beyond canonical models and lifestyles.

What is the vagina? This seemingly simple question has a rather complex answer, depending on whether we use a functional or a developmental definition. The terminal portion of the female reproductive tract that opens to the environment initially served as a conduit for eggs to be laid, and in species with external fertilization the distal oviduct may be specialized for oviposition but there is no vagina. In animals with internal fertilization, this terminal section of the oviduct interacts with the sperm and the intromittent organ leading to functional specialization of this region that we often call a vagina in insects and some vertebrates. Here we address the evolution, morphology and diverse functions of the vagina and some of the unknown questions that remain to be addressed in the study of this remarkable structure.

Michael Weiss and Darren Croft introduce Orcas (Orcinus orca) also known as killer whales.

Q&A with Åke Lindström who studies bird migration and biology.

Exceptional preservation of fossils has often been attributed to the actions of bacteria that aid in the preservation of soft tissues that normally decay rapidly. However, it is well known that fungi play a major role in organic matter decomposition, biogeochemical cycling of elements, and metal-mineral transformations in modern ecosystems. Although the fungal fossil record can be traced back over a billion years, there are only a few recorded examples of fungal roles in fossilization. In this research, we have carried out a detailed geobiological investigation on early Pleistocene hyena coprolites (fossilized dung) in an attempt to ascertain possible fungal involvement in their formation. Using an advanced microscopic and mineralogical approach, we found that numerous hydroxyapatite nanofibers (25-34 nm on average), interwoven to form spheroidal structures, constituted the matrix of the coprolites in addition to food remains. These structures were found to be extremely similar in texture and mineral composition to biominerals produced during laboratory culture of a common saprophytic and geoactive fungus, Aspergillus niger, in the presence of a solid source of calcium (Ca) and phosphorus (P). This observation, and our other data obtained, strongly suggests that fungal metabolism can provide a mechanism that can result in fossil biomineralization, and we hypothesize, therefore, that this may have contributed to the formation of well-preserved fossils (Lagerstätten) in the geological record. The characteristic polycrystalline nanofibers may also have served as a potential biosignature for fungal life in early Earth and extraterrestrial environments.

Pain serves critical biological functions, but under some circumstances it is best suppressed. A new study identifies a channel, a neuropeptide, and a pair of neurons in the fly brain that suppress pain.

Malaria-transmitting mosquitoes are skilled human hunters, selectively choosing their prey based on a complex array of sensory cues. A new study unveils a distinct pattern of preference for human-associated olfactory cues that underlies the selective behavior of these mosquitoes.

Crows can learn to categorise line lengths into experimenter-defined categories. The crow's brain codes and recodes line lengths in individual neurons in the nidopallium caudolaterale, part of the telencephalon.

Rindos and Leibhold introduce the invasive pest, the spongy moth.

Starfish, graptolites and humans look as different as can be, yet are more closely related to each other than to any other phylum. Disc-shaped Cambrian fossils join the dots between these disparate body plans to plot out their evolutionary origins.

Perceptual learning is often thought to rely primarily on low-level visual areas. A new study shows that learning with a partner can improve perceptual learning performance, demonstrating that higher cognitive processes play a larger role in perceptual learning than previously supposed.

All animals use two different strategies to navigate: idiothetic or movement-based navigation, and allothetic or landmark-based navigation. A new study reveals that compromised idiothetic navigation underlies disrupted grid cell coding in an early stage Alzheimer's disease mouse model.

The belief that learning can be modulated by social context is mainly supported by high-level value-based learning studies. However, whether social context can even modulate low-level learning such as visual perceptual learning (VPL) is still unknown. Unlike traditional VPL studies in which participants were trained singly, here, we developed a novel dyadic VPL paradigm in which paired participants were trained with the same orientation discrimination task and could monitor each other's performance. We found that the social context (i.e., dyadic training) led to a greater behavioral performance improvement and a faster learning rate compared with the single training. Interestingly, the facilitating effects could be modulated by the performance difference between paired participants. Functional magnetic resonance imaging (fMRI) results showed that, compared with the single training, social cognition areas including bilateral parietal cortex and dorsolateral prefrontal cortex displayed a different activity pattern and enhanced functional connectivities to early visual cortex (EVC) during the dyadic training. Furthermore, the dyadic training resulted in more refined orientation representation in primary visual cortex (V1), which was closely associated with the greater behavioral performance improvement. Taken together, we demonstrate that the social context, learning with a partner, can remarkably augment the plasticity of low-level visual information process by means of reshaping the neural activities in EVC and social cognition areas, as well as their functional interplays.

Using functional imaging and neural circuit reconstructions, a recent study reveals head direction neurons in the anterior hindbrain of zebrafish that resemble insect head-direction cells to a surprising degree.

The human visual system extracts both the three-dimensional (3D) shape and the material properties of surfaces from single images.1,2,3,4,5,6,7,8,9,10,11,12,13,14 Understanding this remarkable ability is difficult because the problem of extracting both shape and material is formally ill posed: information about one appears to be needed to recover the other.14,15,16,17 Recent work has suggested that a particular class of image contours formed by a surface curving smoothly out of sight (self-occluding contours) contains information that co-specifies both surface shape and material for opaque surfaces.18 However, many natural materials are light permeable (translucent); it is unknown whether there is information along self-occluding contours that can be used to distinguish opaque and translucent materials. Here, we present physical simulations, which demonstrate that variations in intensity generated by opaque and translucent materials are linked to different shape attributes of self-occluding contours. Psychophysical experiments demonstrate that the human visual system exploits the different forms of intensity-shape covariation along self-occluding contours to distinguish opaque and translucent materials. These results provide insight into how the visual system manages to solve the putatively ill-posed problem of extracting both the shape and material properties of 3D surfaces from images.

Islands are arenas for a range of striking evolutionary phenomena, including the island rule - the tendency for larger animals to shrink and smaller animals to enlarge. A new study of insular mammals finds such body size shifts predispose these evolutionary marvels to greater extinction risk.

The vertebrate spine is a metameric structure composed of alternating vertebral bodies (centra) and intervertebral discs.1 Recent studies in zebrafish have shown that the epithelial sheath surrounding the notochord differentiates into alternating cartilage-like (col2a1/col9a2+) and mineralizing (entpd5a+) segments which serve as a blueprint for centra formation.2,3,4,5 This process also defines the trajectories of migrating sclerotomal cells that form the mature vertebral bodies.4 Previous work demonstrated that notochord segmentation is typically sequential and involves the segmented activation of Notch signaling.2 However, it is unclear how Notch is activated in an alternating and sequential fashion. Furthermore, the molecular components that define segment size, regulate segment growth, and produce sharp segment boundaries have not been identified. In this study, we uncover that a BMP signaling wave acts upstream of Notch during zebrafish notochord segmentation. Using genetically encoded reporters of BMP activity and signaling pathway components, we show that BMP signaling is dynamic as axial patterning progresses, leading to the sequential formation of mineralizing domains in the notochord sheath. Genetic manipulations reveal that type I BMP receptor activation is sufficient to ectopically trigger Notch signaling. Moreover, loss of Bmpr1ba and Bmpr1aa or Bmp3 function disrupts ordered segment formation and growth, which is recapitulated by notochord-specific overexpression of the BMP antagonist, Noggin3. Our data suggest that BMP signaling in the notochord sheath precedes Notch activation and instructs segment growth, facilitating proper spine morphogenesis.

Charles Darwin reasoned that because climbing plants are freed from the need to be mechanically self-supporting, their stems can remain thin, elongate quickly, and efficiently colonize and display leaves in well-illuminated areas where trellises are available1. Herein, I report that this tremendous exploratory capacity also applies below-ground - roots of woody climbers (i.e., lianas) consistently beat tree roots to fertilized soil patches, apparently because lianas do not invest in thick roots. This claim is based on results of a greenhouse experiment in which individual seedlings (N = 5 individuals per species) of four liana and four tree species were planted in the centers of 60 x 15 cm rectangular sand-filled boxes. In the direction of a usually covered Plexiglas end wall, a nutrient gradient was established by adding increasing amounts of slow-release fertilizer in four 6 cm-wide vertical bands; no nutrients were added in the other direction. Entire plants were harvested by section when their first root reached the end wall. Roots from all four liana species reached the highly fertilized end of the planting box faster than all tree roots (Figure 1A; for statistical results, see the Supplementary Information). A Vitis rotundifolia root arrived after just 67 days, a Campsis radicans root after 84 days, another Vitis root after 91 days, and then a Wisteria sinensis root after 94 days, and the fastest root of Gelsemium sempervirens grew the 24 cm to the end wall in 149 days. In contrast to the liana species, the fastest tree roots reached the end wall in 235 days for Magnolia grandiflora, 253 days for Quercus hemisphaerica, 263 days for Nyssa sylvatica, and 272 days for Liquidambar styraciflua. This capacity to explore soil rapidly may help explain why lianas are such potent below-ground competitors2 and why their removal substantially increases tree growth rates3,4.

Symbiotic nitrogen fixation (SNF) provides much of the N utilized by leguminous plants throughout growth and development. Legumes may simultaneously establish symbiosis with different taxa of microbial symbionts. Yet, the mechanisms used to steer associations toward symbionts that are most propitious across variations in soil types remain mysterious. Here, we demonstrate that GmRj2/Rfg1 is responsible for regulating symbiosis with multiple taxa of soybean symbionts. In our experiments, the GmRj2/Rfg1SC haplotype favored association with Bradyrhizobia, which is mostly distributed in acid soils, whereas the GmRj2/Rfg1HH haplotype and knockout mutants of GmRj2/Rfg1SC associated equally with Bradyrhizobia and Sinorhizobium. Association between GmRj2/Rfg1 and NopP, furthermore, appeared to be involved in symbiont selection. Furthermore, geographic distribution analysis of 1,821 soybean accessions showed that GmRj2/Rfg1SC haplotypes were enriched in acidic soils where Bradyrhizobia were the dominant symbionts, whereas GmRj2/Rfg1HH haplotypes were most prevalent in alkaline soils dominated by Sinorhizobium, and neutral soils harbored no apparent predilections toward either haplotype. Taken together, our results suggest that GmRj2/Rfg1 regulates symbiosis with different symbionts and is a strong determinant of soybean adaptability across soil regions. As a consequence, the manipulation of the GmRj2/Rfg1 genotype or application of suitable symbionts according to the haplotype at the GmRj2/Rfg1 locus might be suitable strategies to explore for increasing soybean yield through the management of SNF.

Deuterostomes are characterized by some of the most widely divergent body plans in the animal kingdom. These striking morphological differences have hindered efforts to predict ancestral characters, with the origin and earliest evolution of the group remaining ambiguous. Several iconic Cambrian fossils have been suggested to be early deuterostomes and hence could help elucidate ancestral character states. However, their phylogenetic relationships are controversial. Here, we describe new, exceptionally preserved specimens of the discoidal metazoan Rotadiscus grandis from the early Cambrian Chengjiang biota of China. These reveal a previously unknown double spiral structure, which we interpret as a chordate-like covering to a coelomopore, located adjacent to a horseshoe-shaped tentacle complex. The tentacles differ in key aspects from those seen in lophophorates and are instead more similar to the tentacular systems of extant pterobranchs and echinoderms. Thus, Rotadiscus exhibits a chimeric combination of ambulacrarian and chordate characters. Phylogenetic analyses recover Rotadiscus and closely related fossil taxa as stem ambulacrarians, filling a significant morphological gap in the deuterostome tree of life. These results allow us to reconstruct the ancestral body plans of major clades of deuterostomes, revealing that key traits of extant forms, such as a post-anal region, gill bars, and a U-shaped gut, evolved through convergence.

Primates have evolved sophisticated, visually guided reaching behaviors for interacting with dynamic objects, such as insects, during foraging.1,2,3,4,5 Reaching control in dynamic natural conditions requires active prediction of the target's future position to compensate for visuo-motor processing delays and to enhance online movement adjustments.6,7,8,9,10,11,12 Past reaching research in non-human primates mainly focused on seated subjects engaged in repeated ballistic arm movements to either stationary targets or targets that instantaneously change position during the movement.13,14,15,16,17 However, those approaches impose task constraints that limit the natural dynamics of reaching. A recent field study in marmoset monkeys highlights predictive aspects of visually guided reaching during insect prey capture among wild marmoset monkeys.5 To examine the complementary dynamics of similar natural behavior within a laboratory context, we developed an ecologically motivated, unrestrained reach-to-grasp task involving live crickets. We used multiple high-speed video cameras to capture the movements of common marmosets (Callithrix jacchus) and crickets stereoscopically and applied machine vision algorithms for marker-free object and hand tracking. Contrary to estimates under traditional constrained reaching paradigms, we find that reaching for dynamic targets can operate at incredibly short visuo-motor delays around 80 ms, rivaling the speeds that are typical of the oculomotor systems during closed-loop visual pursuit.18 Multivariate linear regression modeling of the kinematic relationships between the hand and cricket velocity revealed that predictions of the expected future location can compensate for visuo-motor delays during fast reaching. These results suggest a critical role of visual prediction facilitating online movement adjustments for dynamic prey.

Humans can learn tasks explicitly, as they can often describe the rules they have used to learn the task.1,2,3 Animals, however, are thought to learn tasks implicitly (i.e., purely associatively).2,3 That is, they gradually learn the correlation or association between the stimulus (or response) and the outcome. Both humans and pigeons can learn matching, where a sample stimulus indicates which one of two stimuli matches the sample. The 1-back reinforcement task is a difficult version of matching in which a correct response on trial N is rewarded only following a response on trial N + 1 (independent of the response on trial N + 1),4 and the correct response on trial N + 1 indicates whether a reward will occur on trial N + 2, and so forth. Humans do not appear to be able to learn the 1-back rule.5 Pigeons, however, do show 1-back reinforcement learning,6,7 and they appear to do so implicitly by gradually learning the correlation between their response on one trial and the outcome on the next trial (because all other relations are uncorrelated with the outcome). They learn the task slowly and to a level below what would be expected had they learned it explicitly. The present results, together with research with humans,7 suggest that there are times when human explicit learning may interfere with the ability of humans to learn. Pigeons, however, are not "distracted" by attempts at explicit learning, and thus they are able to learn this and other similar tasks.6,7,8.

The African malaria mosquito Anopheles gambiae exhibits a strong innate drive to seek out humans in its sensory environment, classically entering homes to land on human skin in the hours flanking midnight. To gain insight into the role that olfactory cues emanating from the human body play in generating this epidemiologically important behavior, we developed a large-scale multi-choice preference assay in Zambia with infrared motion vision under semi-field conditions. We determined that An. gambiae prefers to land on arrayed visual targets warmed to human skin temperature during the nighttime when they are baited with carbon dioxide (CO2) emissions reflective of a large human over background air, body odor from one human over CO2, and the scent of one sleeping human over another. Applying integrative whole body volatilomics to multiple humans tested simultaneously in competition in a six-choice assay, we reveal high attractiveness is associated with whole body odor profiles from humans with increased relative abundances of the volatile carboxylic acids butyric acid, isobutryic acid, and isovaleric acid, and the skin microbe-generated methyl ketone acetoin. Conversely, those least preferred had whole body odor that was depleted of carboxylic acids among other compounds and enriched with the monoterpenoid eucalyptol. Across expansive spatial scales, heated targets without CO2 or whole body odor were minimally or not attractive at all to An. gambiae. These results indicate that human scent acts critically to guide thermotaxis and host selection by this prolific malaria vector as it navigates towards humans, yielding intrinsic heterogeneity in human biting risk.

The global surge in demand for metals such as cobalt and nickel has created unprecedented interest in deep-sea habitats with mineral resources. The largest area of activity is a 6 million km2 region known as the Clarion-Clipperton Zone (CCZ) in the central and eastern Pacific, regulated by the International Seabed Authority (ISA). Baseline biodiversity knowledge of the region is crucial to effective management of environmental impact from potential deep-sea mining activities, but until recently this has been almost completely lacking. The rapid growth in taxonomic outputs and data availability for the region over the last decade has allowed us to conduct the first comprehensive synthesis of CCZ benthic metazoan biodiversity for all faunal size classes. Here we present the CCZ Checklist, a biodiversity inventory of benthic metazoa vital to future assessments of environmental impacts. An estimated 92% of species identified from the CCZ are new to science (436 named species from a total of 5,578 recorded). This is likely to be an overestimate owing to synonyms in the data but is supported by analysis of recent taxonomic studies suggesting that 88% of species sampled in the region are undescribed. Species richness estimators place total CCZ metazoan benthic diversity at 6,233 (+/-82 SE) species for Chao1, and 7,620 (+/-132 SE) species for Chao2, most likely representing lower bounds of diversity in the region. Although uncertainty in estimates is high, regional syntheses become increasingly possible as comparable datasets accumulate. These will be vital to understanding ecological processes and risks of biodiversity loss.

Arbuscular mycorrhizal fungi colonize the roots of most plants, forming a near-ubiquitous symbiosis1 that is typically characterized by the bi-directional exchange of fungal-acquired nutrients for plant-fixed carbon.2 Mycorrhizal fungi can form below-ground networks3,4,5,6 with potential to facilitate the movement of carbon, nutrients, and defense signals across plant communities.7,8,9 The importance of neighbors in mediating carbon-for-nutrient exchange between mycorrhizal fungi and their plant hosts remains equivocal, particularly when other competing pressures for plant resources are present. We manipulated carbon source and sink strengths of neighboring pairs of host plants through exposure to aphids and tracked the movement of carbon and nutrients through mycorrhizal fungal networks with isotope tracers. When carbon sink strengths of both neighboring plants were increased by aphid herbivory, plant carbon supply to extraradical mycorrhizal fungal hyphae was reduced, but mycorrhizal phosphorus supply to both plants was maintained, albeit variably, across treatments. However, when the sink strength of only one plant in a pair was increased, carbon supply to mycorrhizal fungi was restored. Our results show that loss of carbon inputs into mycorrhizal fungal hyphae from one plant may be ameliorated through inputs of a neighbor, demonstrating the responsiveness and resilience of mycorrhizal plant communities to biological stressors. Furthermore, our results indicate that mycorrhizal nutrient exchange dynamics are better understood as community-wide interactions between multiple players rather than as strict exchanges between individual plants and their symbionts, suggesting that mycorrhizal C-for-nutrient exchange is likely based more on unequal terms of trade than the "fair trade" model for symbiosis.

Evolution has generated an enormous variety of morphological, physiological, and behavioral traits in animals. How do behaviors evolve in different directions in species equipped with similar neurons and molecular components? Here we adopted a comparative approach to investigate the similarities and differences of escape behaviors in response to noxious stimuli and their underlying neural circuits between closely related drosophilid species. Drosophilids show a wide range of escape behaviors in response to noxious cues, including escape crawling, stopping, head casting, and rolling. Here we find that D. santomea, compared with its close relative D. melanogaster, shows a higher probability of rolling in response to noxious stimulation. To assess whether this behavioral difference could be attributed to differences in neural circuitry, we generated focused ion beam-scanning electron microscope volumes of the ventral nerve cord of D. santomea to reconstruct the downstream partners of mdIV, a nociceptive sensory neuron in D. melanogaster. Along with partner interneurons of mdVI (including Basin-2, a multisensory integration neuron necessary for rolling) previously identified in D. melanogaster, we identified two additional partners of mdVI in D. santomea. Finally, we showed that joint activation of one of the partners (Basin-1) and a common partner (Basin-2) in D. melanogaster increased rolling probability, suggesting that the high rolling probability in D. santomea is mediated by the additional activation of Basin-1 by mdIV. These results provide a plausible mechanistic explanation for how closely related species exhibit quantitative differences in the likelihood of expressing the same behavior.

The vestibular system in the inner ear plays a central role in sensorimotor control by informing the brain about the orientation and acceleration of the head. However, most experiments in neurophysiology are performed using head-fixed configurations, depriving animals of vestibular inputs. To overcome this limitation, we decorated the utricular otolith of the vestibular system in larval zebrafish with paramagnetic nanoparticles. This procedure effectively endowed the animal with magneto-sensitive capacities: applied magnetic field gradients induced forces on the otoliths, resulting in robust behavioral responses comparable to those evoked by rotating the animal by up to 25°. We recorded the whole-brain neuronal response to this fictive motion stimulation using light-sheet functional imaging. Experiments performed in unilaterally injected fish revealed the activation of a commissural inhibition between the brain hemispheres. This magnetic-based stimulation technique for larval zebrafish opens new perspectives to functionally dissect the neural circuits underlying vestibular processing and to develop multisensory virtual environments, including vestibular feedback.

Blastocystis is the most prevalent microbial eukaryote in the human and animal gut, yet its role as commensal or parasite is still under debate. Blastocystis has clearly undergone evolutionary adaptation to the gut environment and possesses minimal cellular compartmentalization, reduced anaerobic mitochondria, no flagella, and no reported peroxisomes. To address this poorly understood evolutionary transition, we have taken a multi-disciplinary approach to characterize Proteromonas lacertae, the closest canonical stramenopile relative of Blastocystis. Genomic data reveal an abundance of unique genes in P. lacertae but also reductive evolution of the genomic complement in Blastocystis. Comparative genomic analysis sheds light on flagellar evolution, including 37 new candidate components implicated with mastigonemes, the stramenopile morphological hallmark. The P. lacertae membrane-trafficking system (MTS) complement is only slightly more canonical than that of Blastocystis, but notably, we identified that both organisms encode the complete enigmatic endocytic TSET complex, a first for the entire stramenopile lineage. Investigation also details the modulation of mitochondrial composition and metabolism in both P. lacertae and Blastocystis. Unexpectedly, we identify in P. lacertae the most reduced peroxisome-derived organelle reported to date, which leads us to speculate on a mechanism of constraint guiding the dynamics of peroxisome-mitochondrion reductive evolution on the path to anaerobiosis. Overall, these analyses provide a launching point to investigate organellar evolution and reveal in detail the evolutionary path that Blastocystis has taken from a canonical flagellated protist to the hyper-divergent and hyper-prevalent animal and human gut microbe.

Converging evidence from human and rodent studies suggests that disrupted grid cell coding in the medial entorhinal cortex (MEC) underlies path integration behavioral deficits during early Alzheimer's disease (AD). However, grid cell firing relies on both self-motion cues and environmental features, and it remains unclear whether disrupted grid coding can account for specific path integration deficits reported during early AD. Here, we report in the J20 transgenic amyloid beta (Aβ) mouse model of early AD that grid cells were spatially unstable toward the center of the arena, had qualitatively different spatial components that aligned parallel to the borders of the environment, and exhibited impaired integration of distance traveled via reduced theta phase precession. Our results suggest that disrupted early AD grid coding reflects reduced integration of self-motion cues but not environmental information via geometric boundaries, providing evidence that grid cell impairments underlie path integration deficits during early AD.

Diatoms, dinoflagellates, and coccolithophores are dominant groups of marine eukaryotic phytoplankton that are collectively responsible for the majority of primary production in the ocean.1 These phytoplankton contain additional intracellular membranes around their chloroplasts, which are derived from ancestral engulfment of red microalgae by unicellular heterotrophic eukaryotes that led to secondary and tertiary endosymbiosis.2 However, the selectable evolutionary advantage of these membranes and the physiological significance for extant phytoplankton remain poorly understood. Since intracellular digestive vacuoles are ubiquitously acidified by V-type H+-ATPase (VHA),3 proton pumps were proposed to acidify the microenvironment around secondary chloroplasts to promote the dehydration of dissolved inorganic carbon (DIC) into CO2, thus enhancing photosynthesis.4,5 We report that VHA is localized around the chloroplasts of centric diatoms and that VHA significantly contributes to their photosynthesis across a wide range of oceanic irradiances. Similar results in a pennate diatom, dinoflagellate, and coccolithophore, but not green or red microalgae, imply the co-option of phagocytic VHA activity into a carbon-concentrating mechanism (CCM) is common to secondary endosymbiotic phytoplankton. Furthermore, analogous mechanisms in extant photosymbiotic marine invertebrates6,7,8 provide functional evidence for an adaptive advantage throughout the transition from endosymbiosis to symbiogenesis. Based on the contribution of diatoms to ocean biogeochemical cycles, VHA-mediated enhancement of photosynthesis contributes at least 3.5 Gtons of fixed carbon per year (or 7% of primary production in the ocean), providing an example of a symbiosis-derived evolutionary innovation with global environmental implications.

Although many recent tracking studies have uncovered considerable variation in the migratory routines of birds,1,2 the source of this variation is surprisingly poorly discussed.3 We hypothesize that a wealth of possible factors, including factors other than genetics, translate into these variable outcomes. To demonstrate how factors that are not inherited can shape migratory routine during development, we performed a translocation and delayed-release experiment with juvenile, hand-raised black-tailed godwits Limosa limosa limosa that were carefully matched for ancestral background, releasing siblings 1,000 km apart. Translocated juveniles adopted the spatiotemporal pattern of migration that is habitual for the population at the release location rather than the origin. This leads to the rejection of the hypothesis that the migration of inexperienced birds is only shaped by pre-release factors, including genes, maternal material in the eggs, and a common environment from hatching to fledging. Instead, these findings are consistent with inexperienced migrants also developing their knowledge and capacities through contextual individual learning,4 the precise nature of which now warrants study. The fact that hand-raised godwits, depending on the context in which they are released, can be induced to show different migratory routines, wintering sites, and breeding locations from their siblings indicates that processes during development offer the substrate for rapid adaptation of long-distance migration.

Once formed, the fate of memory is uncertain. Subsequent offline interactions between even different memory types (actions versus words) modify retention.1,2,3,4,5,6 These interactions may occur due to different oscillations functionally linking together different memory types within a circuit.7,8,9,10,11,12,13 With memory processing driving the circuit, it may become less susceptible to external influences.14 We tested this prediction by perturbing the human brain with single pulses of transcranial magnetic stimulation (TMS) and simultaneously measuring the brain activity changes with electroencephalography (EEG15,16,17). Stimulation was applied over brain areas that contribute to memory processing (dorsolateral prefrontal cortex, DLPFC; primary motor cortex, M1) at baseline and offline, after memory formation, when memory interactions are known to occur.1,4,6,10,18 The EEG response decreased offline (compared with baseline) within the alpha/beta frequency bands when stimulation was applied to the DLPFC, but not to M1. This decrease exclusively followed memory tasks that interact, revealing that it was due specifically to the interaction, not task performance. It remained even when the order of the memory tasks was changed and so was present, regardless of how the memory interaction was produced. Finally, the decrease within alpha power (but not beta) was correlated with impairment in motor memory, whereas the decrease in beta power (but not alpha) was correlated with impairment in word-list memory. Thus, different memory types are linked to different frequency bands within a DLPFC circuit, and the power of these bands shapes the balance between interaction and segregation between these memories.

Acute avoidance of dangerous temperatures is critical for animals to prevent or minimize injury. Therefore, surface receptors have evolved to endow neurons with the capacity to detect noxious heat so that animals can initiate escape behaviors. Animals including humans have evolved intrinsic pain-suppressing systems to attenuate nociception under some circumstances. Here, using Drosophila melanogaster, we uncovered a new mechanism through which thermal nociception is suppressed. We identified a single descending neuron in each brain hemisphere, which is the center for suppression of thermal nociception. These Epi neurons, for Epione-the goddess of soothing of pain-express a nociception-suppressing neuropeptide Allatostatin C (AstC), which is related to a mammalian anti-nociceptive peptide, somatostatin. Epi neurons are direct sensors for noxious heat, and when activated they release AstC, which diminishes nociception. We found that Epi neurons also express the heat-activated TRP channel, Painless (Pain), and thermal activation of Epi neurons and the subsequent suppression of thermal nociception depend on Pain. Thus, while TRP channels are well known to sense noxious temperatures to promote avoidance behavior, this work reveals the first role for a TRP channel for detecting noxious temperatures for the purpose of suppressing rather than enhancing nociception behavior in response to hot thermal stimuli.

White campion (Silene latifolia, Caryophyllaceae) was the first vascular plant where sex chromosomes were discovered. This species is a classic model for studies on plant sex chromosomes due to presence of large, clearly distinguishable X and Y chromosomes that originated de novo about 11 million years ago (mya), but lack of genomic resources for this relatively large genome (∼2.8 Gb) remains a significant hurdle. Here we report S. latifolia female genome assembly integrated with sex-specific genetic maps of this species, focusing on sex chromosomes and their evolution. The analysis reveals a highly heterogeneous recombination landscape with strong reduction in recombination rate in the central parts of all chromosomes. Recombination on the X chromosome in female meiosis primarily occurs at the very ends, and over 85% of the X chromosome length is located in a massive (∼330 Mb) gene-poor, rarely recombining pericentromeric region (Xpr). The results indicate that the non-recombining region on the Y chromosome (NRY) initially evolved in a relatively small (∼15 Mb), actively recombining region at the end of the q-arm, possibly as a result of inversion on the nascent X chromosome. The NRY expanded about 6 mya via linkage between the Xpr and the sex-determining region, which may have been caused by expanding pericentromeric recombination suppression on the X chromosome. These findings shed light on the origin of sex chromosomes in S. latifolia and yield genomic resources to assist ongoing and future investigations into sex chromosome evolution.

The ability of fungi to mineralize substrates is a common but underestimated phenomenon. Now, researchers have demonstrated the usefulness of this process in fossilization by documenting the formation of hydroxyapatite nanofibres. This opens new avenues in palaeomycology and palaeontology.