Diversity Of Rhizobium From The Roots Of Different Soybeans Varieties And Soil

Soybean is one of the most important crops,it can form nitrogen-fixation symbiosis with rhizobia.Therefore,exploring the mutual adaptation of rhizobia and soybean varieties deeply can improve the soybean production and breed the soybean materials.Through rhizobium separation technology,molecular ecology technology and Metagenomics sequencing technology,this experiment intends to plant 26 different varieties soybeans to explore the symbiotic matching differences between different varieties soybeans and soybean rhizobia,analysis the diversity and function of rhizobia in rhizosphere,finally expound the enriching process of soybean rhizobia on the soil community,including partial structure and function.There were 310 rhizobia isolated from the roots of 26 different soybeans varieties which was planted in the farmland in Yangling.Based upon analysis of 16 S rRNA genes sequences,98.4% of isolates belonged to Sinorhizobium and 1.6% of isolates belonged to Rhizobium,and no the Bradyrhizobium was detected.Furtherly,the phylogenetic relationships of all isolates were conformed by the housekeeping gene atpD and rpoB.All results showed there is no obvious rhizobial differences between different soybean varieties.Through high-throughput sequencing,the results showed that the different varieties soybeans had different bacterial community in no-rhizosphere and rhizosphere.From the bulk soil,rhizosphere to nodules,the composition of bacterial communities of the soybeans,including rhizobia,has been gradually selected and filtered.In the bulk soil,the main rhizobia were Bradyrhizobium and Mesorhizobium,but in the rhizosphere: the main rhizobia were Sinorhizobium/Ensifer.The analysis for composition and abundance of the genes associated with nitrogen fixation in the soil showed nodABC,nifB and nifH genes were also enriched with different degree,and also detected form the rhizobia isolated from the soybeans nodules,it revealed that the corresponding rhozbia were selected as the symbiotic partners.This study reveals the genetic diversity of rhizobia from different soybeans varieties and phylogenetic relationship of symbiotic genes.At the same time,the enriching process of the soybean rhizobia from the root zone to rhizosphere to nodules can provide an important clues to understand the selection of rhizobia by soybeans varieties.