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The full potential for using DNA barcodes for profiling functional trait diversity has yet to be determined in plants and animals; thus, we outline a general framework for quantifying functional trait diversity of insect community DNA and propose and assess the accuracy of three methods for achieving this. We built a novel dataset of traits and DNA barcodes for wild bees in China. An informatics framework was developed for phylogeny‐based integration of these data and prediction of traits for any subject barcodes, which was compared with two distance‐based methods. For Phylogenetic Assignment, we additionally conducted a species‐level analysis of publically available bee trait data. Under the specimen‐level dataset, the rate of trait assignment was negatively correlated with distance between the query and the nearest trait‐known reference, for all methods. Phylogenetic Assignment was found to perform best under several criteria; particularly, it had the lowest false‐positive rate (rarely returning a state prediction where success was unlikely; where the distance from query to the nearest reference was high). For a wider range of compiled traits, conservative life‐history traits showed the highest rates of assignment; for example, sociality was predicted with confidence at 53%, parasitism at 44% and nest location at 33%. As outlined herein, automated trait assignment might be applied at scale to either barcodes or metabarcodes. With further compilation and databasing of DNA barcode and trait data, the rate and accuracy of trait assignment is expected to increase to the point of being a widely viable and informative approach. [ABSTRACT FROM AUTHOR]

The microbiomes associated with bee nests influence colony health through various mechanisms, although it is not yet clear how honeybee congeners differ in microbiome assembly processes, in particular the degrees to which floral visitations and the environment contribute to different aspects of diversity. We used DNA metabarcoding to sequence bacterial 16S rRNA from honey and stored pollen from nests of 4 honeybee species (Apis cerana, A. dorsata, A. florea, and A. laboriosa) sampled throughout Yunnan, China, a global biodiversity hotspot. We developed a computational pipeline integrating multiple databases for quantifying key facets of diversity, including compositional, taxonomic, phylogenetic, and functional ones. Further, we assessed candidate drivers of observed microbiome dissimilarity, particularly differences in floral visitations, habitat disturbance, and other key environmental variables. Analyses revealed that microbiome alpha diversity was broadly equivalent across the study sites and between bee species, apart from functional diversity which was very low in nests of the reclusive A. laboriosa. Turnover in microbiome composition across Yunnan was driven predominantly by pollen composition. Human disturbance negatively impacted both compositional and phylogenetic alpha diversity of nest microbiomes, but did not correlate with microbial turnover. We herein make progress in understanding microbiome diversity associated with key pollinators in a biodiversity hotspot, and provide a model for the use of a comprehensive informatics framework in assessing pattern and drivers of diversity, which enables the inclusion of explanatory variables both subtly and fundamentally different and enables elucidation of emergent or unexpected drivers. [ABSTRACT FROM AUTHOR]

Summary: Determining whether isotope fractionation occurs during root water uptake is a prerequisite for using stem or xylem water isotopes to trace water sources. However, it is unclear whether isotope fractionation occurs during root water uptake in gramineous crops.We conducted prevalidation experiments to estimate the isotope measurement bias associated with cryogenic vacuum distillation (CVD). Next, we assessed isotope fractionation during root water uptake in two common agronomic crops, wheat (Triticum aestivum L.) and maize (Zea mays L.), under flooding after postdrought stress conditions.Cryogenic vacuum distillation caused significant depletion of 2H but negligible effects on 18O for both soil and stem water. Surprisingly CVD caused depletion of 2H and enrichment of 18O in root water. Stem and root water δ18O were more than soil water δ18O, even considering the uncertainty of CVD. Soil water 18O was depleted compared with irrigation water 18O in the pots with plants but enriched relative to irrigation water 18O in the pots without plants.These results indicate that isotope fractionation occurred during wheat and maize root water uptake after full irrigation and led to a heavy isotope enrichment in stem water. Therefore, the xylem/stem water isotope approach widely used to trace water sources should be carefully evaluated. [ABSTRACT FROM AUTHOR]

Lateral roots and root hairs are essential portions of cotton roots. However, the morphology and lifespan of cotton (Gossypium hirsutum L.) lateral roots and root hairs in response to nitrogen stress have remained unknown. Two cotton cultivars were assessed when no nitrogen and normal nitrogen (138 mg N·kg−1 soil) were added. The daily acquisitions of root phenotype information including the lateral root angle, lateral root density, lateral root diameter, lateral root lifespan, root hair length, root hair density, and root hair lifespan, were obtained in situ by a self‐designed platform of RhizoPots equipped with high‐resolution scanners. Nitrogen starvation significantly reduced the growth of shoots and roots, although there was less reduction of roots than shoots. Root hairs were the first organ to respond to nitrogen deficiency through morphological changes. The lateral root diameter and angle as well as the root hair lifespan decreased significantly under nitrogen stress. However, nitrogen deficiency dramatically increased the lateral root lifespan, root hair density and length. Our results demonstrate that low nitrogen can induce notable changes in lateral roots and root hairs, which may play a crucial role in the adjustment to nitrogen uptake, particularly in species that can adapt to low nitrogen availability. [ABSTRACT FROM AUTHOR]

Roots strongly influence the growth and yield of field crops. We characterized root morphological traits of 10 winter wheat varieties in order to determine the extent they were influenced by the environments and impacted grain yield under two irrigation regimes at Bushland (a cooler, drier site with clay loam soil) and Uvalde (a warmer, wetter site with clay soil) in Texas, USA, from 2015 to 2017. Major root traits, including root diameter, specific root length (SRL), root surface area (SSA), tissue mass density (TMD), root length density (RLD), and root weight density, were measured and related to one another and to grain yield. RLD of wheat decreased but SRL and SSA increased with soil depth. Irrigation was second to environment in affecting root traits. Compared with Uvalde, the environment of Bushland promoted deeper root growth, higher TMD, but reduced SRL and SSA. Water deficit inhibited RLD and root: shoot ratio at Bushland, but moderately promoted them at Uvalde. Both SRL and RLD were positively associated with grain yield, with the former relation stronger under drought. The dichotomy of "conservative" versus "acquisitive" root strategy partially explained the variations of root traits of winter wheat in contrasting environments. [ABSTRACT FROM AUTHOR]

Bulk leaf carbon isotopic composition (δ13Cbulk) has been widely used to investigate leaf level water use efficiency (WUEl) in efforts to boost grain yield relative to crop water use. Although widely used for isotopic analyses, the bulk leaf represents a complex mixture of compounds. Single‐compound isotopic analyses carry diagnostic advantages over bulk analyses in a range of applications and may also serve as surrogates for WUEl and grain yield in crops. This study tests whether compound‐specific carbon and hydrogen isotopes of leaf wax n‐alkanes (δ13Calk and δDalk) and n‐alcohols (δ13Calc) could be used as surrogates for WUEl and grain yield using conventional δ13Cbulk as a reference. Ten winter wheat (Triticum aestivum L.) cultivars were planted under two irrigation treatments (full and deficit irrigation) at Uvalde (wet location) and Amarillo (dry location), TX, during two growing seasons. There were significant relationships between δ13Calk or δDalk and δ13Cbulk, indicating they can all serve as surrogates for WUEl in most cases. Compared with δ13Cbulk, we found stronger relationships between δ13Calk at Uvalde or δDalk under deficit irrigation at Amarillo and grain yield. The δ13Calk also had higher broad‐sense heritability than δ13Cbulk, indicating larger cultivar effects in δ13Calk than in δ13Cbulk. In contrast, the δ13Calc was not consistently related with δ13Cbulk or grain yield. Our study introduces the idea that δ13Calk and δDalk may supplement conventional δ13Cbulk with potential to assist in the breeding process when selecting for high‐WUE and high‐yielding cultivars. [ABSTRACT FROM AUTHOR]