微生物氮利用效率(NUE)描述了微生物用于生长的氮相对于吸收的总有机氮的比例,是调节土壤氮循环的重要参数。^(18)O-H_(2)O法和生态酶化学计量模型广泛应用于评估微生物NUE。然而,目前关于氮富集对森林土壤微生物NUE影响的研究仍不充分...微生物氮利用效率(NUE)描述了微生物用于生长的氮相对于吸收的总有机氮的比例,是调节土壤氮循环的重要参数。^(18)O-H_(2)O法和生态酶化学计量模型广泛应用于评估微生物NUE。然而,目前关于氮富集对森林土壤微生物NUE影响的研究仍不充分,这会影响对土壤氮供应的准确预测。该研究以亚热带罗浮栲(Castanopsis faberi)林土壤为研究对象,通过施加尿素模拟大气氮沉降,设置对照(CK,0 kg N·hm^(-2)·a^(-1))、低氮(LN,40 kg N·hm^(-2)·a^(-1))和高氮(HN,80 kg N·hm^(-2)·a^(-1))3个处理,使用^(18)O-H_(2)O法和生态酶化学计量模型,比较不同氮富集水平下土壤微生物NUE的差异。同时还测定了土壤理化性质、微生物生物量、胞外酶活性、化学计量不平衡等,以期探究调控微生物NUE对氮富集响应的因子。结果表明,不同方法得到的微生物NUE均随着氮富集速率的增加而降低。不同氮处理的矢量角度值均大于55°,这表明该研究区土壤微生物整体上受到磷限制,但氮富集并没有加剧该样地土壤微生物受到的磷限制。相反,氮富集对微生物碳氮不平衡具有显著的负效应,且微生物NUE与微生物碳氮不平衡呈显著的正相关关系。综上,氮富集可能不利于亚热带森林土壤氮储存。为改善这一现状,建议进一步调控土壤生态化学计量平衡。展开更多
Soil bacteria are integral to ecosystem functioning,significantly contributing to nutrients cycling and organic matter decomposition,and enhancing soil structure.This research considered the composition and dynamics o...Soil bacteria are integral to ecosystem functioning,significantly contributing to nutrients cycling and organic matter decomposition,and enhancing soil structure.This research considered the composition and dynamics of soil bacterial communities under different vegetation types(native Quercus brantii Lindl.and Amygdalus scoparia Spach,and non-native Pinus eldarica Medw.and Cupressus arizonica Greene.)in Zagros mountain area of Iran.This study involved a comparative analysis of soil culturable heterotrophic bacterial communities in spring(wet season)and summer(dry season)to clarify the effects of seasonal changes and vegetation on the dynamics of soil microorganisms.Soil samples were randomly collected under the canopies of various tree species and a control area,yielding a total of 48 composite samples analyzed for bacterial composition.Results indicated that 11 Gram-negative(e.g.,Citrobacter freundii,Enterobacter cloacae,Escherichia coli,Klebsiella oxytoca,Klebsiella pneumoniae,etc.)and 2 Gram-positive(Staphylococcus epidermidis and Staphylococcus aureus)bacteria were identified,showing significant seasonal variation.Specifically,53.85%of bacterial species were common to both seasons,with notable shifts in community composition observed between spring and summer,highlighting a higher abundance of Gram-negative species in spring.Bacterial community structure was significantly influenced by vegetation type,with various tree species shaping distinct microbial assemblages.Moreover,Pearson's correlations revealed that soil properties,particularly pH,phosphorus,and moisture content,were critical drivers of bacterial diversity and abundance.Our findings underscore the dynamic nature of soil bacterial communities in response to seasonal and vegetation changes,emphasizing the importance of repeated temporal sampling for accurate assessments of microbial diversity.Understanding these microbial dynamics is essential for improving soil management strategies and enhancing ecosystem resilience,particularly in arid and semi-arid areas where environmental fluctuations play a pivotal role.This research not only confirms our hypotheses but also enhances our understanding of soil biogeochemical processes and informs future vegetation management practices.展开更多
Catalpa bungei,a fast-growing timber tree,is threatened by the lepidopteran pest Omphisa plagialis.Previous studies in our laboratory successfully generated transgenic C.bungei lines overexpressing Cry genes(Cry1Ab,Cr...Catalpa bungei,a fast-growing timber tree,is threatened by the lepidopteran pest Omphisa plagialis.Previous studies in our laboratory successfully generated transgenic C.bungei lines overexpressing Cry genes(Cry1Ab,Cry2A,and Cry9-2)that exhibited resistance to O.plagialis,but their potential impact on soil bacterial communities remains unclear.In this study,we analyzed nine transgenic C.bungei lines(three independent lines for each Cry gene)to characterize their rhizosphere bacterial communities using high-throughput sequencing of the 16S ribosomal DNA(rDNA)V4-V5 regions.A total of 628 amplicon sequence variants(ASVs)were shared among all transgenic and wild-type(WT)lines,forming a stable core microbiome dominated by Proteobacteria,Bacteroidota,Acidobacteriota,and Actinobacteriota.Alpha diversity showed no significant differences,while beta diversity revealed minor but distinct compositional shifts.Cry1Ab lines exhibited higher abundances of fast-growing taxa,particularly Proteobacteria and Bacteroidota;Cry2A lines displayed intermediate profiles,whereas Cry9-2 lines were nearly indistinguishable from WT communities.Linear discriminant analysis of the effect size revealed significant enrichment of taxa such as Burkholderiaceae and Ralstonia in the Cry1Ab rhizosphere,in contrast to the higher abundance of Chloroflexi in the WT.Functional predictions indicated consistent metabolic pathways across all treatments,suggesting strong ecological redundancy.This study demonstrates minimal impact on rhizosphere microbial communities in transgenic C.bungei plants.The Cry9-2 construct exhibited superior environmental stability,whereas the Cry1Ab construct caused only slight but ecologically acceptable shifts.These findings support the ecological safety of Bt-transgenic C.bungei and identify Cry9-2 as a particularly favorable candidate for forestry applications.This comparative evaluation of three Cry genes in a tree species provides a framework for future gene-specific biosafety assessments in woody plants.展开更多
文摘微生物氮利用效率(NUE)描述了微生物用于生长的氮相对于吸收的总有机氮的比例,是调节土壤氮循环的重要参数。^(18)O-H_(2)O法和生态酶化学计量模型广泛应用于评估微生物NUE。然而,目前关于氮富集对森林土壤微生物NUE影响的研究仍不充分,这会影响对土壤氮供应的准确预测。该研究以亚热带罗浮栲(Castanopsis faberi)林土壤为研究对象,通过施加尿素模拟大气氮沉降,设置对照(CK,0 kg N·hm^(-2)·a^(-1))、低氮(LN,40 kg N·hm^(-2)·a^(-1))和高氮(HN,80 kg N·hm^(-2)·a^(-1))3个处理,使用^(18)O-H_(2)O法和生态酶化学计量模型,比较不同氮富集水平下土壤微生物NUE的差异。同时还测定了土壤理化性质、微生物生物量、胞外酶活性、化学计量不平衡等,以期探究调控微生物NUE对氮富集响应的因子。结果表明,不同方法得到的微生物NUE均随着氮富集速率的增加而降低。不同氮处理的矢量角度值均大于55°,这表明该研究区土壤微生物整体上受到磷限制,但氮富集并没有加剧该样地土壤微生物受到的磷限制。相反,氮富集对微生物碳氮不平衡具有显著的负效应,且微生物NUE与微生物碳氮不平衡呈显著的正相关关系。综上,氮富集可能不利于亚热带森林土壤氮储存。为改善这一现状,建议进一步调控土壤生态化学计量平衡。
文摘Soil bacteria are integral to ecosystem functioning,significantly contributing to nutrients cycling and organic matter decomposition,and enhancing soil structure.This research considered the composition and dynamics of soil bacterial communities under different vegetation types(native Quercus brantii Lindl.and Amygdalus scoparia Spach,and non-native Pinus eldarica Medw.and Cupressus arizonica Greene.)in Zagros mountain area of Iran.This study involved a comparative analysis of soil culturable heterotrophic bacterial communities in spring(wet season)and summer(dry season)to clarify the effects of seasonal changes and vegetation on the dynamics of soil microorganisms.Soil samples were randomly collected under the canopies of various tree species and a control area,yielding a total of 48 composite samples analyzed for bacterial composition.Results indicated that 11 Gram-negative(e.g.,Citrobacter freundii,Enterobacter cloacae,Escherichia coli,Klebsiella oxytoca,Klebsiella pneumoniae,etc.)and 2 Gram-positive(Staphylococcus epidermidis and Staphylococcus aureus)bacteria were identified,showing significant seasonal variation.Specifically,53.85%of bacterial species were common to both seasons,with notable shifts in community composition observed between spring and summer,highlighting a higher abundance of Gram-negative species in spring.Bacterial community structure was significantly influenced by vegetation type,with various tree species shaping distinct microbial assemblages.Moreover,Pearson's correlations revealed that soil properties,particularly pH,phosphorus,and moisture content,were critical drivers of bacterial diversity and abundance.Our findings underscore the dynamic nature of soil bacterial communities in response to seasonal and vegetation changes,emphasizing the importance of repeated temporal sampling for accurate assessments of microbial diversity.Understanding these microbial dynamics is essential for improving soil management strategies and enhancing ecosystem resilience,particularly in arid and semi-arid areas where environmental fluctuations play a pivotal role.This research not only confirms our hypotheses but also enhances our understanding of soil biogeochemical processes and informs future vegetation management practices.
基金funded by the Chinese Academy of Forestry-Special funds for basic scientific research service expenses of the central level public welfare research institutes(Grant No.CAFYBB2020QD001)the National Natural Science Foundation of China(Grant Nos.32101550,32271917)+1 种基金Jiangsu Agricultural Science and Technology Innovation Fund(Grant No.CX(24)3052)National Forestry and Grassland Administration’s Center for Science and Technology Development Projects(Grant No.KJZXSA202202).
文摘Catalpa bungei,a fast-growing timber tree,is threatened by the lepidopteran pest Omphisa plagialis.Previous studies in our laboratory successfully generated transgenic C.bungei lines overexpressing Cry genes(Cry1Ab,Cry2A,and Cry9-2)that exhibited resistance to O.plagialis,but their potential impact on soil bacterial communities remains unclear.In this study,we analyzed nine transgenic C.bungei lines(three independent lines for each Cry gene)to characterize their rhizosphere bacterial communities using high-throughput sequencing of the 16S ribosomal DNA(rDNA)V4-V5 regions.A total of 628 amplicon sequence variants(ASVs)were shared among all transgenic and wild-type(WT)lines,forming a stable core microbiome dominated by Proteobacteria,Bacteroidota,Acidobacteriota,and Actinobacteriota.Alpha diversity showed no significant differences,while beta diversity revealed minor but distinct compositional shifts.Cry1Ab lines exhibited higher abundances of fast-growing taxa,particularly Proteobacteria and Bacteroidota;Cry2A lines displayed intermediate profiles,whereas Cry9-2 lines were nearly indistinguishable from WT communities.Linear discriminant analysis of the effect size revealed significant enrichment of taxa such as Burkholderiaceae and Ralstonia in the Cry1Ab rhizosphere,in contrast to the higher abundance of Chloroflexi in the WT.Functional predictions indicated consistent metabolic pathways across all treatments,suggesting strong ecological redundancy.This study demonstrates minimal impact on rhizosphere microbial communities in transgenic C.bungei plants.The Cry9-2 construct exhibited superior environmental stability,whereas the Cry1Ab construct caused only slight but ecologically acceptable shifts.These findings support the ecological safety of Bt-transgenic C.bungei and identify Cry9-2 as a particularly favorable candidate for forestry applications.This comparative evaluation of three Cry genes in a tree species provides a framework for future gene-specific biosafety assessments in woody plants.
