Across two phylogeographic breaks: Quaternary evolutionary history of a mountain aspen (Populus rotundifolia) in the Hengduan Mountains

Biogeographical barriers to gene flow are central to plant phylogeography.In East Asia,plant distribution is greatly influenced by two phylogeographic breaks,the Mekong-Salween Divide and Tanaka-Kaiyong Line,however,few studies have investigated how these barriers affect the genetic diversity of species that are distributed across both.Here we used 14 microsatellite loci and four chloroplast DNA fragments to examine genetic diversity and distribution patterns of 49 populations of Populus rotundifolia,a species that spans both the Mekong-Salween Divide and the Tanaka-Kaiyong Line in southwestern China.Demographic and migration hypotheses were tested using coalescent-based approaches.Limited historical gene flow was observed between the western and eastern groups of P.rotundifolia,but substantial flow occurred across both the Mekong-Salween Divide and Tanaka-Kaiyong Line,manifesting in clear admixture and high genetic diversity in the central group.Wind-borne pollen and seeds may have facilitated the dispersal of P.rotundifolia following prevalent northwest winds in the spring.We also found that the Hengduan Mountains,where multiple genetic barriers were detected,acted on the whole as a barrier between the western and eastern groups of P.rotundifolia.Ecological niche modeling suggested that P.rotundifolia has undergone range expansion since the last glacial maximum,and demographic reconstruction indicated an earlier population expansion around 600 Ka.The phylogeographic pattern of P.rotundifolia reflects the interplay of biological traits,wind patterns,barriers,niche differentiation,and Quaternary climate history.This study emphasizes the need for multiple lines of evidence in understanding the Quaternary evolution of plants in topographically complex areas.

新媒体环境对职业院校心理健康教育的影响及策略分析

新媒体环境影响职业院校学生的心理发展和心理健康教育。职业院校应积极发挥新媒体优势,搭建服务平台,完善教育网络,加强队伍建设,创新教育方式,聚焦意识形态,丰富校园文化,促进心理工作由平面单一向立体多元发展,提高心理教育的吸引力、感染力和实效性。

Characterization of the chemical fungicides-responsive and bacterial pathogen-preventing Bacillus licheniformis in rice spikelet

Seed-borne bacterial pathogens cause severe yield loss and biotoxin contamination in rice,leading to increasing concern on the global food supply and environmental safety.Plant native microbes play an important role in defending against diseases,but their actions are often influ-enced by the chemical fungicides applied in the field.Here,Bacillus licheniformis mmj was isolated from rice spikelet,which uniquely showed not only fungicide-responsiveness but also broad-spectrum antimicrobial activity against major rice bacterial pathogens including Xanthomonas oryzae pv.oryzae,Burkholderia plantari and Burkholderia glumae.To understand the hallmark underlying the environmental adaptation and anti-microbial activity of B.licheniformis mmj,the genome sequence was determined by SMRT and subjected to bioinformatics analysis.Genome sequence analysis enabled the identification of a set of antimicrobial-resistance and antibacterial activity genes together with an array of harsh environment-adaptive genes.Moreover,B.licheniformis mmj metabolites were analyzed with gas chromatography coupled to triple quadrupole mass spectrometry,and the volatile components that were linked with the antimicrobial activity were preliminarily profiled.Collectively,the present findings reveal the genomic and metabolic landscapes underlying fungicide-responsive B.licheniformis,which offers a new opportunity to design harsh environment-adaptive biopesticides to cope with prevalent bacterial phytopathogens.

Reprogramming of phytopathogen transcriptome by a non-bactericidal pesticide residue alleviates its virulence in rice

Bacteria equipped with virulence systems based on highly bioactive small molecules can circumvent their host's defense mechanisms.Pathogens employing this strategy are currently threatening global rice production.In the present study,variations in the virulence of the highly destructive Barkholderiaplantarii were observed in different rice-producing regions.The environment-linked variation was not attributable to any known host-related or external factors.Co-occurrence analyses indicated a connection between reduced virulence and 5-Amino-l,3,4-thiadiazole-2-thiol(ATT),a non-bactericidal organic compound.ATT,which accumulates in rice plants during metabolization of specific agrochemicals,was found to reduce virulence factor secretion by B.plantarii up to 88.8%and inhibit pathogen virulence by hijacking an upstream signaling cascade.Detailed assessment of the newly discovered virulence inhibitor resulted in mechanistic insights into positive effects of ATT accumulation in plant tissues.Mechanisms of virulence alleviation were deciphered by integrating high-throughput data,gene knockout mutants,and molecular interaction assays.TroK,a histidine protein kinase in a two-component system that regulates virulence factor secretion,is likely the molecular target antagonized by ATT.Our findings provide novel insights into virulence modulation in an important plant-pathogen system that relies on the host's metabolic activity and subsequent signaling interference.

Improving the Thermal Stability of Cu_3N Films by Addition of Mn

Mn-doped Cu_3N films were deposited by cylindrical magnetron sputtering equipment on the common glass at room temperature.The incorporation of Mn can change the preferred growth orientation from Cu-rich plane(111) to N-rich plane(100) due to the improvement of nitridation of Cu.The shrinkage of the lattice and the X-ray photoelectron spectroscopy results reveal that Mn should replace Cu atoms in the lattice or be segregated in the grain boundaries.The thickness of Mn-doped film is smaller than that of the pure one due to the less physisorption of N species among the columnar grains.The mean grain size and the energy gap become larger with increasing Mn concentration to 2.2 at.%and then decrease when the concentration of Mn is higher than 2.2 at.%.Notably,weak doping of 1.5 at.%Mn successfully promotes the decomposed temperature by^50℃.According to the results of XRD and SEM for Mndoped films annealed in vacuum,a possible decomposed mechanism with increasing the annealing temperature is proposed.