不同紫云英品种根瘤内生细菌的类群和多样性分析

Endophytic Microbes in Root Nodules of Different Cultivars of Astragalus Sinicus L.

【目的】阐释紫云英根瘤内生菌的群落结构,为研发根瘤菌菌剂及了解固氮机制提供依据。【方法】以福建省种植的不同紫云英品种的根瘤为材料,借助Illumina Miseq PE300测序平台,以16S rRNA基因为靶标,研究不同紫云英品种的根瘤内生细菌的多样性。【结果】不同品种会影响紫云英根瘤内生细菌的类群和多样性。浙紫5号(ZZ5)的优势属为假单胞菌属(Pseudomonas),其余品种根瘤内生细菌的优势属均为中慢生根瘤菌属(Mesorhizobium)。闽紫8号(MZ8)、信阳(XY)和浙紫5号的根瘤内生细菌的多样性指数(Shannon)较高,除了共生固氮的中慢生根瘤菌外,还包括丰富的非根瘤菌,如假单胞菌属、寡养单胞菌属(Stenotrophomonas)、杜擀氏菌属(Duganella)、泛菌属(Pantoea)、欧文氏菌属(Erwinia)等。闽紫8号、信阳和浙紫5号这3个品种根瘤中含有较高丰度的致病菌大黄欧文氏菌(Erwinia rhapontici)和菠萝泛菌PA13(Pantoea ananatis PA13)。【结论】紫云英品种对根瘤内生细菌的群落结构有一定影响,浙紫5号的根瘤内生细菌主要为具促生作用的非根瘤菌假单胞菌,而其余品种为具固氮能力的根瘤菌,在生产实际中可以采用紫云英混种的方式达到固氮促生的双重功效。

Objective Being crucial to the development of rhizobium inoculants and the understanding on the associated mechanisms of soil nitrogen fixation,community structure of the endophytic microorganisms in root nodules of Astragalus sinicus L.was investigated.Method Endophytic microbial community in the root nodules of 7 cultivars of A.sinicus planted in Fujian was analyzed with the Illumina Miseq PE300 sequencing platform using 16S rRNA as the target gene.Result The microbial composition of endophytic community in the nodules of the different cultivars varied.For instance,the predominant genus in ZZ5 root nodules was Pseudomonas,but it was Mesorhizobium in other cultivars.Furthermore,high Shannon indices were found in the root nodules of MZ8,XY,and ZZ5 with diverse non-rhizobial endophytes like Pseudomonas,Stenotrophomonas,Duganella,Erwinia,etc.In contrast,high relative abundances of pathogens,such as Erwinia rhapontici and Pantoea ananatis PA13 existed in the root nodules of MZ8,XY,and ZZ5.Conclusions Significant microbial variations in the endophytic communities were evident among the different varieties of A.sinicus planted in Fujian.The predominant genus in the root nodules of ZZ5 was non-rhizobial,growth-promoting Pesudomonas,while it was rhizobia for the other cultivars.