Center for Rhizosphere Biology, Department of Horticulture and Landscape Architecture, Colorado State University, Fort Collins, CO, USA.
ISME J. 2014 Apr;8(4):790-803. doi: 10.1038/ismej.2013.196. Epub 2013 Nov 7.
There is a concerted understanding of the ability of root exudates to influence the structure of rhizosphere microbial communities. However, our knowledge of the connection between plant development, root exudation and microbiome assemblage is limited. Here, we analyzed the structure of the rhizospheric bacterial community associated with Arabidopsis at four time points corresponding to distinct stages of plant development: seedling, vegetative, bolting and flowering. Overall, there were no significant differences in bacterial community structure, but we observed that the microbial community at the seedling stage was distinct from the other developmental time points. At a closer level, phylum such as Acidobacteria, Actinobacteria, Bacteroidetes, Cyanobacteria and specific genera within those phyla followed distinct patterns associated with plant development and root exudation. These results suggested that the plant can select a subset of microbes at different stages of development, presumably for specific functions. Accordingly, metatranscriptomics analysis of the rhizosphere microbiome revealed that 81 unique transcripts were significantly (P<0.05) expressed at different stages of plant development. For instance, genes involved in streptomycin synthesis were significantly induced at bolting and flowering stages, presumably for disease suppression. We surmise that plants secrete blends of compounds and specific phytochemicals in the root exudates that are differentially produced at distinct stages of development to help orchestrate rhizosphere microbiome assemblage.
人们已经充分认识到根分泌物能够影响根际微生物群落的结构。然而，我们对于植物发育、根系分泌物和微生物组装配之间的联系的了解还很有限。在这里，我们分析了与拟南芥在四个不同发育时间点（幼苗期、营养生长期、抽薹期和开花期）相关的根际细菌群落的结构。总的来说，细菌群落结构没有显著差异，但我们观察到，幼苗期的微生物群落与其他发育时间点明显不同。在更精细的水平上，厚壁菌门、放线菌门、拟杆菌门、蓝细菌门和这些门内的特定属都遵循着与植物发育和根系分泌物相关的特定模式。这些结果表明，植物可以在不同的发育阶段选择一组特定的微生物，可能是为了特定的功能。因此，对根际微生物组的宏转录组学分析表明，81 个独特的转录本在植物发育的不同阶段显著（P<0.05）表达。例如，与链霉素合成相关的基因在抽薹和开花阶段被显著诱导，可能是为了抑制疾病。我们推测，植物在根分泌物中分泌化合物的混合物和特定的植物化学物质，这些物质在不同的发育阶段以不同的方式产生，以帮助协调根际微生物组的装配。
