入侵植物小蓬草的细菌群落组成和多样性研究

Composition and Diversity of Bacterial Community of the Alien Invasive Plant (Conyza canadensis L.)

生物入侵现象严重危害生态系统的健康,其中外来植物入侵是生物入侵中的重要组成,会对农业、林业、畜牧业产生直接的经济危害。选取生长状况良好的菊科外来入侵植物小蓬草(Conyza canadensis L.,Asteraceae)植株,利用16S rRNA基因的高通量测序技术和后续分析,探索小蓬草生境中的土壤及其根和叶的细菌群落组成和多样性,并分析表面消毒、冷冻干燥保存和不同研磨方法等处理方式对研究结果的影响。结果表明:小蓬草根样本细菌群落中OTU的数目最多,其次是土壤,小蓬草叶样本的细菌群落中OTU的数目最低;小蓬草细菌群落Alpha多样性在土壤样本中最高,其次是小蓬草根,小蓬草叶的细菌群落Alpha多样性最低;在门的水平,在土壤和小蓬草叶、根的细菌群落均以变形菌门和放线菌门丰度最高,此外在小蓬草根和叶的细菌群落丰度较高的还有厚壁菌门,在土壤细菌群落丰度较高的则是拟杆菌门;小蓬草根和叶细菌群落的优势属包括假单胞菌属(Pseudomonas)、芽孢杆菌属(Bacillus)、甲基杆菌属(Methylobacterium)、鞘氨醇单胞菌属(Sphingomonas)、根瘤菌属(Rhizobium)和无色杆菌属(Achromobacter)等,这些优势属可能包含植物益生菌,并对小蓬草适应不良环境提供一定的帮助;是否进行表面消毒处理的小蓬草叶和根样本的细菌群落组成和多样性有明显的差异,表明小蓬草的根表和根内以及叶表和叶内的细菌群落存在明显的差异;机器研磨、冷冻干燥保存处理的小蓬草样本与人工研磨并及时处理的小蓬草样本相比,其细菌群落组成并没有明显的差异,表明这些处理方式对植物微生物组的研究结果不会产生明显的影响。该研究结果可为微生物在植物入侵机制中所起的作用提供数据支持。

Biological invasion seriously endangers ecosystem health.Invasive plants are the most important part of biological invasion which can cause economic harm to agriculture,forestry and animal husbandry.We select well-growing plants of the invasive species Conyza canadensis L.(Asteraceae) and use high-throughput sequencing analysis of 16S rRNA gene to explore the composition and diversity of bacterial communities of the soil,roots and leaves associated with C.canadensis. The data may support the important role of microorganisms in plant invasion mechanisms.The effects of surface sterilization,freeze-drying preservation and mechanically grinding on the study results are also analyzed.The results show that the number of OTUs in the root bacterial communities of C.canadensis is the highest,followed by soil,and the lowest in leaf bacterial communities.The Alpha diversity of bacterial communities decreases significantly from the soil to root and leaf samples.Proteobacteria and Actinomycetes are the highest abundant phyla in the bacterial communities of soil,leaf and root samples.In addition,Firmicutes is one of the most abundant phyla in leaf and root bacterial communities and Bacteroidetes is one of the most abundant in soil bacterial communities.The dominant genera of the C.canadensis root and leaf microbiota are Pseudomonas,Bacillus,Methylobacterium,Sphingomonas,Rhizobium and Achromobacter. These genera include plant probiotics according to previous studies and may be helpful for C.canadensis to adapt to adverse environment.There are significant differences in the composition and diversity of bacterial communities from leaf/root samples applied with or without surface sterilization treatment,demonstrating leaf/root microbiota are significantly different on surface and in endosphere.No significant differences are observed between samples grounded by a machine and preserved after freeze-dying and those grounded by hand and processed immediately,indicating that mechanically grinding and freeze-drying preservation of plant samples will not have effect on the results of plant microbiome studies.