| In order to understand the community composition of endophytic nitrogen-fixing bacteria in the naked barley, and the effect of planting regions on the diversity of endophytic nitrogen-fixing bacteria, endophytic nitrogen-fixing bacteria in naked barley roots from different planting regions were isolated and their diversity was investigated. In this study, culture techniques were used to isolate and purify endophytic nitrogen-fixing bacteria from the roots of naked barley ZQ2000 planted in Lhasa, Nyingchi, and Xigaze. Nitrogenase activity of the strains was determined, and dissolved phosphorus and potassium and characteristics of IAA production of the strains with high nitrogenase activity were examined. Taxonomy of the strains with high nitrogenase activity was studied by 16S rDNA gene sequencing and phylogenetic tree construction. The results showed that 37 endophytic nitrogen-fixing bacteria were isolated and purified using Ashby medium, including eleven strains with high nitrogenase activity, accounting for 27% of the isolates. While among these eleven strains with high nitrogenase activity, six strains were capable to secrete IAA, and two strains were capable to dissolve potassium, and one strain were capable to dissolve phosphorus. The results of 16S rDNA sequencing showed that five of the eleven strains with high nitrogenase activity belonged to Bacillus, which was the dominant genus, and the rest strains belonged to Gemmatimonas, Sphingomonas, Devosia, Agrobacterium, Mesorhizobium and Burkholderia. |
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