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Widespread recombination suppression facilitates plant sex chromosome evolution

Classical models suggest that recombination rates on sex chromosomes evolve in a stepwise manner to localize sexually antagonistic variants in the sex in which they are beneficial, thereby lowering rates of recombination between X and Y chromosomes. However, it is also possible that sex chromosome formation occurs in regions with pre-existing recombination suppression. To evaluate these possibilities, we constructed linkage maps and a chromosome-scale genome assembly for the dioecious plant Rumex hastatulus. This species has a polymorphic karyotype with a young neo-sex chromosome, resulting from a Robertsonian fusion between the X chromosome and an autosome, in part of its geographical range. We identified the shared and neo-sex chromosome using comparative genetic maps of the two cytotypes. We found that sex-linked regions of both the ancestral and the neo-sex chromosome are embedded in large regions of low recombination. Furthermore, our comparison of the recombination landscape of the neo-sex chromosome to its autosomal homologue indicates that low recombination rates preceded sex linkage. These patterns are not unique to the sex chromosomes; all chromosomes were characterized by massive regions of suppressed recombination spanning most of each chromosome. This represents an extreme case of the periphery-biased recombination seen in other systems with large chromosomes. Across all chromosomes, gene and repetitive sequence density correlated with recombination rate, with patterns of variation differing between repetitive element type. Our findings suggest that ancestrally low rates of recombination may facilitate the formation and subsequent evolution of heteromorphic sex chromosomes.

Multiple sequence alignment for the native Norwegian vascular plant phylogeny

Methods: We produced a multi-locus Maximum Likelihood (ML) phylogeny using a combination of newly produced DNA sequences from herbarium specimens and sequences available from public repositories. We combined the phylogeny with species occurrence data to estimate phylogenetic diversity and phylogenetic endemism across Norway, using a spatial randomization to judge statistical significance. We used multiple-model inference to identify environmental variables that contributed the most to the patterns of phylogenetic diversity. Finally, we estimated phylogenetic turnover and used this to identify Norwegian plant assemblages in terms of composition and evolutionary history. Results: Our ML phylogeny contained 87% of all currently described native Norwegian vascular plants. Assemblages were phylogenetically overdispersed in warmer and wetter regions of Norway, as well as in regions with a longer post-glacial history. In cold and dry regions, plant assemblages were phylogenetically clustered, and characterised by neo-endemism, while the mild and wet regions were characterised by both paleo- and neo-endemism. Phylogenetic diversity was positively correlated with summer temperature and habitat heterogeneity, and peaked in the southeast of Norway. Main conclusions: Both contemporary ecological factors (climate and habitat heterogeneity), and post-glacial history seem to have shaped the phylogenetic structure of the flora of Norway. The flora in the far north of Norway appear to be a result of recent diversification while the coastal regions are assemblages of deeper lineages. Our results suggest that there is an evolutionary signal in the distribution of the Norwegian vascular flora.

opencc-zeroJan 2020View details →

Data from: Trait-based formal definition of plant functional types and functional communities in the multi-species and multi-traits context

The concepts of traits, plant functional types (PFT), and functional communities are effective tools for the study of complex phenomena such as plant community assembly. Here, we (1) suggest a procedure formalising the classification of response traits to construct a PFT system; (2) integrate the PFT, and species compositional data to formally define functional communities; and, (3) identify environmental drivers that underpin the functional-community patterns.A species–trait data set featuring species pooled from two study sites (Eneabba and Cooljarloo, Western Australia), both supporting kwongan vegetation (sclerophyllous scrub and woodland communities), was subjected to classification to define PFTs. Species of both study sites were replaced with the newly derived PFTs and projected cover abundance-weighted means calculated for every plot. Functional communities were defined by classifications of the abundance-weighted PFT data in the respective sites. Distance-based redundancy analysis (using the abundance-weighted community and environmental data) was used to infer drivers of the functional community patterns for each site.A classification based on trait data assisted in reducing trait-space complexity in the studied vegetation and revealed 26 PFTs shared across the study sites. In total, seven functional communities were identified. We demonstrate a putative functional-community pattern-driving effect of soil-texture (clay—sand) gradients at Eneabba (42% of the total inertia explained) and that of water repellence at Cooljarloo (36%). Synthesis. This paper presents a procedure formalising the classification of multiple response traits leading to the delineation of PFTs and functional communities. This step captures plant responses to stresses and disturbance characteristic of kwongan vegetation, including low nutrient status, water stress, and fire (a landscape-level disturbance factor). Our study is the first to introduce a formal procedure assisting their formal recognition. Our results support the role of short-term abiotic drivers structuring the formation of fine-scale functional community patterns in a complex, species-rich vegetation of Western Australia.

Plant size and leaf traits for epiphyte species found in flooded gallery forests and non-flooded gallery forests in Central Brazil

Despite their unique adaptations to thrive in canopy environments without access to soil resources, epiphytes are underrepresented in studies of functional traits and of functional composition of tropical plant communities. We investigated functional traits of spermatophytic (seed-bearing) C3 and CAM epihyte communities in flooded and non-flooded gallery forests in Central Brazil. The two forest types differ in floristic, structure, microclimate and edaphic conditions. We studied plant size, leaf thickness, leaf dry matter content, leaf area, specific leaf area, leaf C, N, P, K, Mg, Ca and C and N stable isotope ratios. Because photosynthetic pathway (C3 or CAM) is an important aspect of ecologial differentiation of spermatophytic epiphytes, we expected that functional trait syndromes in a multivariate space would be more associated with photosynthetic pathway than forest type and changes in abundance of C3 and CAM epiphytes would drive functional trait composition at the community level. C3 and CAM epiphytes segregated in the multivariate trait space, however more complex functional typologies were also evident. Despite lower light levels, CAM epiphytes were more abundant in the flooded gallery forest. There, they accounted for 80% of all individuals, whereas C3 epiphytes dominated in the non-flooded forest. These large differences in the proportion of C3 and CAM epiphytes strongly affected functional trait values at the community level, despite very little intraspecfic variation in trait values between forest types for species that occurred in both forests.

opencc-by-4.0Nov 2020View details →

zenodo36/100

Quantile regression in genomic selection for oligogenic traits in autogamous plants: a simulation study

This study assessed the efficiency of Genomic selection (GS) or genome‐wide selection (GWS), based on Regularized Quantile Regression (RQR), in the selection of genotypes to breed autogamous plant populations with oligogenic traits. To this end, simulated data of an F2 population were used, with traits with different heritability levels (0.10, 0.20 and 0.40), controlled by four genes. The generations were advanced (up to F6) at two selection intensities (10% and 20%). The genomic genetic value was computed by RQR for different quantiles (0.10,0.50 and 0.90), and by the traditional GWS methods, specifically RR-BLUP and BLASSO. A second objective was to find the statistical methodology that allows the fastest fixation of favorable alleles. In general, the results of the RQR model were better than or equal to those of traditional GWS methodologies, achieving the fixation of favorable alleles in most of the evaluated scenarios. At a heritability level of 0.40 and a selection intensity of 10%, RQR (0.50) was the only methodology that fixed the alleles quickly, i.e., in the fourth generation. Thus, it was concluded that the application of RQR in plant breeding, to simulated autogamous plant populations with oligogenic traits, could reduce time and consequently costs, due to the reduction of selfing generations to fix alleles in the evaluated scenarios.

Ecological data from: Combining botanical collections and ecological data to better describe plant community diversity

In this age of rapid biodiversity loss, we must continue to refine our approaches to describing variation in life on Earth. Combining knowledge and research tools from multiple disciplines is one way to better describe complex natural systems. Understanding plant community diversity requires documenting both pattern and process. We must first know which species exist, and where (i.e., taxonomic and biogeographic patterns), before we can determine why they exist there (i.e., ecological and evolutionary processes). Floristic botanists often use collections-based approaches to elucidate biodiversity patterns, while plant ecologists use hypothesis-driven statistical approaches to describe underlying processes. Because of these different disciplinary histories and research goals, floristic botanists and plant ecologists often remain siloed in their work. Here, using a case study from an urban greenway in Colorado, USA, we illustrate that the collections-based, opportunistic sampling of floristic botanists is highly complementary to the transect- or plot-based sampling of plant ecologists. We found that floristic sampling captured a community species pool four times larger than that captured using ecological transects, with rarefaction and non-parametric species estimation indicating that it would be prohibitive to capture the "true" community species pool if constrained to sampling within transects. We further illustrate that the discrepancy in species pool size between approaches led to a different interpretation of the greenway's ecological condition in some cases (e.g., transects missed uncommon cultivated species escaping from nearby gardens) but not others (e.g., plant species distributions among functional groups were similar between species pools). Finally, we show that while using transects to estimate plant relative abundances necessarily trades off with a fuller assessment of the species pool, it is an indispensable indicator of ecosystem health, as evidenced by three non-native grasses contributing to 50% of plant cover along the highly modified urban greenway. We suggest that actively fostering collaborations between floristic botanists and ecologists can create new insights into the maintenance of species diversity at the community scale.

Raster and original working data for the paper Holocene matters: landscape history accounts for current species richness of vascular plants in forests and grasslands of eastern Central Europe

Aim: Current species-richness patterns are sometimes interpreted as a legacy of landscape history, but historical processes shaping the distribution of species during the Holocene are frequently omitted in biodiversity models. Here, we test their importance in modelling current species richness of vascular plants in forest and grassland vegetation. Location: Western Carpathians and adjacent regions. Taxon: Vascular plants. Methods: Numbers of all species and of habitat specialists were extracted from plot records of forest and grassland vegetation. For each plot, environmental and historical data were derived from thematic maps. Historical data related to the persistence of (i) temperate taxa during the Late Glacial and Early Holocene, (ii) open-landscape taxa during the Middle Holocene, and (iii) taiga species during the Late Holocene were based on 112 fossil pollen profiles. Boosted regression trees were used to model spatial patterns in species richness. Results: Historical variables always appeared among the best predictors of current species richness. In light forests, species richness highly mirrored both the Late Glacial (12.5% contribution) and Middle-Holocene (8.6%) landscape history. The latter factor became an important predictor also for species richness of steppe grasslands (8.3%) along with temperature seasonality (11.9%). Species richness of dark coniferous forests was best predicted by the Late-Holocene occurrence of taiga forests (14.8%), which had an even stronger effect on the richness of habitat specialists (20.5%). Main conclusions: Landscape changes since the Last Glacial Maximum are important predictors of current plant species richness. The historical effects were found to be habitat-specific and, because they may interact with recent environmental conditions and anthropogenic pressures, they often show a non-linear relationship with species richness. We provide one possible direction of incorporating past landscape changes into the models of species richness.

Shifts in plant composition mediate grazing effects on carbon cycling in grasslands

Carbon cycling in grasslands can be impacted by livestock grazing, partially as an indirect result of herbivory-induced compositional shifts in the plant community. However, the underlying mechanisms of how these shifts impact carbon cycling are not well documented. We conducted a long-term grazing experiment with four sheep stocking rates in the semi-arid grasslands of Inner Mongolia, China, to examine grazing effects on the ratio of C3 to C4 species (C3:C4), shoot biomass, root biomass, root:shoot, soil respiration, soil C, soil N, and soil C:N between 2014 and 2018. We explored the responses of these carbon metrics to C3:C4 under different grazing treatments and the mechanisms driving grazing-induced carbon loss using structural equation models. Livestock grazing directly shifted plant community composition (i.e., increasing C3:C4) and reduced vegetation carbon (i.e., shoot biomass), whereas grazing effects on belowground carbon were mediated by the interactions of the soil profile (i.e., depth-dependence) and year-to-year variation (e.g., rainfall regulation). Grazing-induced increases in C3:C4 suppressed soil carbon loss by inhibiting the rate of soil respiration. Furthermore, grazing intensity indirectly altered these relationships. Specifically, C3:C4 was positively related to shoot biomass and negatively associated with root:shoot, soil C, and soil N, whereas these relationships were only significant in no-grazed plots. Meanwhile, soil respiration was negatively associated with C3:C4, soil C, soil N, and soil C:N, but a positive relationship with shoot biomass; these relationships were significant only in grazed-plots. <a> Synthesis and applications.</a> Our findings emphasize the functional linkages between community characteristics and ecosystem processes, i.e. shifts in plant community composition play a key role in regulating grassland carbon cycling. These results provide a useful field-observed resource for model development and could improve the guidelines for livestock management and policies regarding climate <a>mitigation.</a>

Data from: Species abundance fluctuations over 31 years are associated with plant-soil feedback in a species-rich mountain meadow

1. Increasing evidence suggest that plant-soil interactions play an essential role in plant community assembly processes. Empirical investigations show that plant species abundance in the field is often related to plant-soil biota interactions, however, the direction of these relations have yielded inconsistent results. 2. We combined unique 31-year long field data on species abundances from a species-rich mountain meadow with single time point plant-soil feedback greenhouse experiments of 24 co-occurring plant species. We tested whether these relations were dynamic in time, whether coupled increases and decreases in abundance between years were related to plant-soil feedback and whether these changes were underlain by years in which manuring was applied. 3. The prevailingly negative relationship between plant-soil feedback and plant relative abundance in the field was significantly time-dependent, which may reconcile the contrasting results in literature. Furthermore, significant coupled oscillations appeared between species relative abundance changes and plant-soil feedback, which were likely moderated by years in which manuring was applied. Our results are consistent with the notion that the more abundant species are stabilised by negative plant-soil feedback, and the less abundant species co-vary with the fluctuations of these more competitive species. 4. Synthesis: Our results project plant-soil feedback as an important regulatory mechanism in plant communities, operating in conjunction with a species' competitive ability and soil nutrient availability. We suggest that negative feedback is particularly prominent in more abundant plant species that profit from more readily available soil nutrients than less abundant species with positive feedback. Negative plant-soil feedback may thus prevent more abundant plant species from outcompeting less abundant plant species, facilitating stable species co-existence.

opencc-by-4.0Dec 2020View details →

zenodo36/100

Interactive Web-based Annotation of Plant MicroRNAs with iwa-miRNA

MicroRNAs (miRNAs) are important regulators of gene expression. The large-scale detection and profiling of miRNAs has accelerated with the development of high-throughput small RNA sequencing (sRNA-Seq) techniques and bioinformatics tools. However, generating high-quality comprehensive miRNA annotations remains challenging, due to the intrinsic complexity of sRNA-Seq data and inherent limitations of existing miRNA predictions. Here, we present iwa-miRNA, a Galaxy-based framework that can facilitate miRNA annotation in plant species by combining computational analysis and manual curation. iwa-miRNA is specifically designed to generate a comprehensive list of miRNA candidates, bridging the gap between already annotated miRNAs provided by public miRNA databases and new predictions from sRNA-Seq datasets. It can also assist users to select promising miRNA candidates in an interactive mode through the automated and manual steps, contributing to the accessibility and reproducibility of genome-wide miRNA annotation. iwa-miRNA is user-friendly and can be easily deployed as a web application for researchers without programming experience. With flexible, interactive, and easy-to-use features, iwa-miRNA is a valuable tool for annotation of miRNAs in plant species with reference genomes. We illustrated the application of iwa-miRNA for miRNA annotation of plant species with varying complexity. The sources codes and web server of iwa-miRNA is freely accessible at: <a href="http://iwa-miRNA.omicstudio.cloud">http://iwa-miRNA.omicstudio.cloud</a>/.

opencc-zeroMar 2021View details →

Data from: Seed size predicts global effects of small mammal seed predation on plant recruitment

We conducted a global literature review and meta-analysis to evaluate whether seed size could predict post-dispersal seed predator effects on seed removal and plant recruitment, respectively. Datasets were built using data extracted from published studies focusing on seed predation by small mammals (see Methods for criteria and data extraction protocol). We found that seed size predicted small mammal seed removal rates and their impacts on plant recruitment consistent with optimal foraging theory, with intermediate seed sizes most strongly impacted globally - for both native and exotic plants. However, differences in seed size distributions among ecosystems conditioned seed predation patterns, with relatively larger-seeded species most strongly affected in grasslands (smallest seeds), and relatively smaller-seeded species most strongly affected in tropical forests (largest seeds). Such size-dependent seed predation has profound implications for coexistence among plants because it may enhance or weaken opposing life-history tradeoffs in an ecosystem-specific manner. Our results suggest that seed size may serve as a key life-history trait that can integrate consumer effects to improve understandings of plant coexistence.

Vegetation cover and plant diversity on cold climate green roofs

Both vegetation abundances and community compositions play important roles for the functions of green roofs (e.g. stormwater retention, habitat provision, aesthetic appearance). However, green roof vegetation can change significantly over time, which may consequently affect the functions related to them. This study investigated vascular plant covers and species compositions on 41 roof sections located in Sweden's subarctic and continental climate zones. For the roof sections with a known originally intended vascular plant composition (n=32), on average 24±9% of the intended species were present in surveys while unintended species made up 69±3% of the the species found. The Intended species dominated plant cover (93±3%) and Sedum acre (58±36% cover) was the most commonly found species. As revealed in previous studies, substrate depth had a positive relationship with plant cover and species richness. The vascular plant cover of the roofs in this study was not related to species richness as hypothesized but instead had a significant negative correlation with moss cover. The results in this study emphasize the importance of substrate depth for both plant abundance and species diversity, and that even in a cold climate, colonising unintended species can have a great contribution to the species richness of green roofs. However, since most colonising species formed sparse cover on the roofs, their potential benefit to green roof functions that benefit from a dense vegetation cover (e.g. stormwater management and thermal performance) could be limited while the intended vegetation performs these functions more effectively.

Data from: Tracking temperate fish reveals their relevance for plant seed dispersal

Seed dispersal is a fundamental process for plant communities, especially now that our changing world demands rapid colonization of new habitats. Long-distance dispersal is especially important for plant population persistence and range expansions. The contribution of fishes to plant seed dispersal in aquatic ecosystems (ichthyochory) has long been overlooked. Although we know fish disperse seeds, it is largely unknown where, when and how far – especially in temperate regions. Here we studied the potential of fish to disperse seeds locally and over long distances, specifically hypothesizing that i) dispersal by fish depends on the season, ii) individual fish contribute differently to seed dispersal, and iii) water regulating structures (barriers) inhibit seed dispersal. We tested our hypotheses by acoustically tracking 71 common carp (Cyprinus carpio) with 21 hydrophones in a 38km-long study system for >2 years in the Netherlands. We calculated potential seed dispersal throughout this system by combining nearly 1.5 million location registrations with experimentally assessed retention times of seeds after ingestion (i.e. time between ingestion and egestion). Seed dispersal on local scales was quantitatively most important during summer and autumn, with high dispersal potential in a range of four kilometres from the location of seed ingestion. Long-distance dispersal up to 16 km was possible at low probabilities in spring. In winter, most seeds were egested within two km. Maximum and median dispersal distances varied widely among individuals, emphasizing variation in effectiveness among individual fish for seed dispersal. Less than two percent of all fish movements reached beyond sluices and weirs, indicating that anthropogenic barriers in freshwater systems strongly reduced the potential of common carp to disperse seeds to these areas. This study shows that common carp can locally disperse plant seeds with high probabilities, and over distances up to 16 km with low probabilities throughout temperate ecosystems. This can contribute to restoration and maintenance of plant community diversity. However, this ecosystem function of fish to plants requires intact fish populations – because not all individual fish contribute equally to dispersal – and unrestricted connectivity throughout aquatic ecosystems.

Size-selective exclusion of mammals and invertebrates differently affects grassland plant communities depending on vegetation type

Human-caused loss of vertebrate and invertebrate animals, defaunation, is increasing, and potentially affects plant community structure of diverse grassland ecosystems worldwide. We experimentally simulated defaunation using size-selective fences to progressively exclude large-, medium- and small-sized mammals, and invertebrates from two subalpine vegetation types in the Swiss National Park (SNP): intensively grazed short-grass and moderately grazed tall-grass vegetation. We assessed plant community properties yearly from 2009 to 2013, and examined treatment effects on plant community structure in the two grassland types. In the short-grass vegetation, the exclusion of large mammals increased total plant biomass, while the exclusion of large and medium-sized mammals increased total, grass and forb biomass compared to when all animals had access. These increases became stronger when also invertebrates were excluded. The exclusion of all mammals and invertebrates increased biomass of grasses by 205%, forbs by 100% and total plant biomass by 118% compared to when all animals had access, hence enhancing relative biomass of grasses from 43.6% to 60%, changing plant species composition and lowering richness of forbs by 16%, the number of plant families by 13% and family-level Shannon diversity by 23%. In contrast to these significant community-level responses found in the short-grass vegetation, there was no evidence that the size-selective exclusion of animals altered the plant community structure of the tall-grass vegetation. The contrasting results were due to the difference in plant community composition prior to our experiment, which were related to differences in quantity and quality of forage and in grazing intensities of herbivores between the two grassland types. Synthesis. Our results showed that different-sized animals, in particular large mammals and invertebrates, contributed to maintain the plant community structure in the short-grass vegetation, highlighting the importance of multiple, functionally different animal groups for ecosystem functioning and stability. In contrast to the short-grass vegetation, we could not detect such a top-down control by animals in the tall-grass vegetation. Our results suggest that potential defaunation effects on grassland plant community structure depend on the degree of grazing pressure release and grassland vegetation type.

opencc-by-4.0Jan 2021View details →

zenodo36/100

Estimating individual level plant traits at scale: input data

This dataset includes the input data to ensure replicability of the results. This dataset include the (1) reflectance for individual tree crowns, extracted from field and algorithmically delineated crowns in 2 NEON sites (OSBS and TALL); (2) the associated measures of tree traits (N%, C%, P%, LMA). The folder should be decompressed inside of the root directory of the project in https://github.com/MarconiS/Estimating-individual-level-plant-traits-at-scale/ for correctly replicate the analysis.

Mangrove diversity enhances plant biomass production and carbon storage in Hainan Island, China

Mangrove forests, one of the highest carbon density ecosystems, are very different from other forests as they occupy saline and tidal habitats. Although previous studies in forests, shrublands, and grasslands have shown a positive effect of biodiversity on plant biomass and carbon storage, it remains unclear whether this relation to biodiversity also exists in mangrove forests. Here, we evaluate the possible effects of mangrove species diversity, structural characteristics, and environmental factors on mangrove biomass production and carbon storage, using survey data from 234 field plots of 30 transects in the mangrove forests along the coastlines of Hainan Island, China, during 2017 and 2018.We found that mangrove species diversity had a positive effect, not only on mangrove biomass production, but also on soil carbon storage. This positive effect was more strongly evident in the forest communities than in either the shrub communities or forest-shrub mixed communities, with the forests type having the biggest mangrove biodiversity and carbon storage. In addition, the diversity effect was affected by structural characteristics, namely, mangrove biomass increased exponentially with tree stem diameter and decreased with tree density. Furthermore, we observed a resource-dependent mediation of the mangrove ecosystem when linking diversity to biomass. The areas with high soil Nitrogen content and Mean annul precipitation (MAP) showed higher mangrove biomass and carbon storage. This suggests that the spatial pattern of mangrove carbon storage and diversity was driven by both climate factors (MAP) and soil fertility (soil N).Our findings suggest that mangrove forests with greater diversity also have higher carbon storage capacities and conservation potential. Thus, biodiversity conservation is crucial for mangrove to mitigate the greenhouse effect. Our findings strengthen the understanding of the diversity effects on mangrove ecosystem services and have important implications for mangrove restoration and conservation.

African sunbirds predominantly pollinate plants useful to humans

Birds provide multiple ecological services that benefit humans including pollination. In Africa, sunbirds are the domi- nant vertebrate pollinator. Here we present a species-level assessment for African sunbirds of the number and relative frequency of their food plants that have useful properties to humans. We conducted this analysis by compiling and integrating known sunbird food plants with useful tropical plant and tropical cultivated plant databases. Across Africa, 68% of the 329 genera and 44% of the 468 species of sunbirds' known food plants are used by humans for medicine, food, building materials, or other uses. Yet most genera and species of useful plants are visited by a small number of sunbird species. The median number of sunbird species that visit a useful genus and species of plant is two and one, re- spectively. Of the 409 genera and 308 species of useful plants that are sunbird pollinated across one or more of the six predominant habitats for sunbirds, 67% of genera and 71% of species are pollinated by sunbird species that are forest or woodland dependent. Additionally, 58% of all genera and 83% of all species of useful plants pollinated by sunbirds are non-cultivated. In Africa, non-cultivated sunbird-pollinated useful plants are almost entirely collected, used, and traded locally rather than regionally or internationally. Our results indicate that African sunbirds provide important ecological services as pollinators that benefit humans, and these services are provided largely at a local scale. Given the decline of invertebrate and vertebrate pollinators both globally and in Africa, sunbirds are important to the long-term conservation of many useful plants in Africa and hence human well-being.

Impact of Helicoverpa zea salivary GOX on stomatal conductance and volatile emission of host plants

This data set contain raw data associated with the manuscript titled "Silencing the alarm: An insect salivary enzyme closes plant stomata and inhibits volatile release". Herbivore-induced plant volatiles (HIPVs) are widely recognized as ecologically important to plant. While the majority of studies focused on the induction of this "cry for help", little is known about whether insect herbivores have evolved mechanisms to reduce the release of HIPVs. Here we show that a caterpillar (Helicoverpa zea) salivary enzyme, glucose oxidase (GOX), commonly secreted on plant leaves causes stomatal closure and reductions in emissions of several HIPVs involved in plant defenses. We found that application of GOX to wounded regions of leaves led to reductions in stomatal conductance on tomato (Solanum lycopersicum) and soybean (Glycine max) for at least two days. The role of GOX in reducing stomatal aperture was confirmed using GOX knockout lines of H. zea (CRISPR-Cas9 mutagenesis), and microscopic observations of stomata. In addition, GOX reduced the emission of several HIPVs during feeding by H. zea, including (Z)-3-hexenol, (Z)-jasmone, and (Z)-3-hexenyl acetate, which are important air borne signals in plant defenses. Our findings highlight a novel mechanism where insect herbivore reduces the release of HIPVs during feeding by targeting fundamental plant structure (i.e. stomata), and the link between of stomatal dynamics and releases of HIPVs. We demonstrate the existence of HIPVs-interfering mechanisms as a potential evolutionary strategy for insect herbivores to interfere with plant air borne signals.

Changes in arthropod community but not plant quality benefit a specialist herbivore on plants under reduced water availability

Plants growing under reduced water availability can affect insect herbivores differently, in some instances benefitting them. However, the forces mediating these positive impacts remain mostly unclear. To identify how water availability impacts plant quality and multitrophic interactions, we conducted manipulative field studies with two populations of the specialist herbivore Pieris rapae, and its host plant, Rorippa indica. We found that P. rapae larvae experienced higher survival on R. indica growing under low water availability compared with plants grown under high water availability. Higher survival of eggs and larvae was related to the reduced abundance of other herbivores and natural enemies. Water availability had differential impacts on other members of the herbivore community by altering plant quality. Low water availability decreased the quality of R. indica to most herbivores, as indicated by reduced abundance in the field and decreased relative growth rate in laboratory feeding assays. In contrast, P. rapae larval performance was not affected by sympatric R. indica grown under different water availability. These results indicate that local P. rapae populations possess physiological adaptations to overcome fluctuations in host quality. Our findings illustrate that reduced water availability is beneficial to a specialist herbivore but detrimental to most other herbivores. Our work highlights the complex effects of the arthropod communities associated with plants in determining the impacts of water availability on insect herbivores.

Plant composition of northern temperate pastures and their disturbance history in Alberta, Canada

This data set includes the plant composition of 102 pastures sampled in north-central Alberta, Canada. Sampled pastures were located in the Central Parkland and Dry Mixed-Wood natural subregions, and were largely comprised of introduced species. In this study, we examined the influence of pasture disturbance history on vegetation, soil properties, and rangeland health. Disturbance history includes estimates of pasture age, cultivation history, fire history, grazing history (including stocking rates), and other pasture management activities/inputs (manure, fertilizer, etc.).