三峡库区消落带草本植物根际细菌群落季节变化特征及功能预测

Seasonal dynamics and functional prediction of bacterial community in the rhizosphere of two suitable herbaceous species in the riparian zone of the Three Gorges Reservoir Area

为了研究三峡库区消落带人工修复植被下不同季节根际细菌群落特征,选取位于三峡库区核心地带的忠县石宝镇汝溪河流域消落带生态修复示范基地内两种适生草本狗牙根(Cynodon dactylon)、牛鞭草(Hemarthria altissima)根际土壤进行16S rDNA高通量测序。研究结果显示:在消落带退水后的春季、夏季、秋季3个季节共检测到细菌60门、151纲、403属,主要优势门为变形菌门、酸杆菌门、拟杆菌门;放线菌门和芽单胞菌门的相对丰度在季节水平上存在差异,夏季芽单胞菌门丰度较高,秋季放线菌门相对丰度显著减少。适生草本的根际土壤细菌α多样性表现出一定的季节变化规律,即秋季>夏季>春季;通过冗余分析发现,影响细菌群落结构的环境因子主要有土壤全磷(TP)、速效钾(AK)、含水量(SWC)、有机质(OM)。基于未观测状态重建的群落系统发育研究(PICRUSt2)功能预测共发现6个一级功能层和45个二级功能层;代谢功能在一级功能层中占比最高,其有利于提高消落带适生草本植物抑制病原菌的能力,促进植物的生长;一级功能层中有两个功能基因表现出季节差异,二级功能层中有14个子功能的相对丰度在不同季节存在显著差异。由此可见,根际细菌群落对狗牙根、牛鞭草两种草本植物能够广泛分布且适生于三峡库区消落带的土壤环境起到了重要的促进作用。

The seasonal dynamics of bacterial diversity within the rhizosphere of suitable herbaceous in the riparian zone of the Three Gorges Reservoir Area were investigated using high-throughput sequencing of bacterial 16S rRNA genes.The results indicated that:60 phyla,151 class,and 403 genera were detected in the rhizosphere soil.The dominant phyla were Proteobacteria,Actinobacteria,and Bacteroidetes.The relative abundance of Actinobacteria and Gemmatimonadetes was different across seasons in the phyla level.The abundance of Gemmatimonadetes was higher in summer,while the relative abundance of Actinobacteria decreased significantly in autumn.Theαdiversity of rhizosphere soil bacteria of suitable herbs showed a certain change pattern,the bacterial diversity index was the highest in autumn and the lowest in spring.The soil total phosphorus(TP),available potassium(AK),soil water content(SWC),and soil organic matter(OM)were important factors that affected the microbial community structures of suitable herbaceous rhizospheres across seasons.PICRUSt2 function prediction analysis of rhizosphere bacterial community revealed 6 biological metabolic pathways and 45 sub-functions.The metabolic function accounted for the highest proportion in the primary functional layer,which was beneficial to improve the ability of suitable herbs to inhibit pathogenic bacteria and promote plant growth.The relative abundance of 2 functions in the level 1 and 14 sub-functions in the level 2 was significantly different across seasons.