Endophytic Bacteria Community Of Populus Euphratica Oliv And The Strains Improving The Salt Tolerance Of Wheat

Populus euphratica Oliv is the only magaphanerophytes with high tolerance to drought and salt that live in the desert of northwestern china. The diversity of endophytic bacteria associated with wild forest of Populus euphratica Oliv located in arid and saline area of Tarim river region was investigated for the first time.197stable isolates were isolated from the roots, stems and leafs of P. euphratica trees and were further classified into102OTUs (operation taxonomic unit) by ARDRA and morphology. Based on the sequence analysis of partial16S rRNA genes,95of the102representative strains of each OTU were identified to belong to21genera, in which the Bacillus and Pseudomonas were the most common genera consisting of49.0%and14.7%of the community respectively. There are7representative strains were only identified to the level of family, namely Sphingobacteriaceae, Enterobacteriaceae, Rhizobiaceae and Phyllobacteriaceae. The proportion of Firmicutes and Gammaproteobacteria exhibited a marked escalating and descending trend respectively along with the increase of bacterial salt tolerance, which indicates the salt tolerance of strains of Firmicutes are generally higher than that of Gammaproteobacteria. It also explained why Bacillus is dominant in the endophytic community of P. euphratica.16.7%of the102representative strains were demonstrated to improve the germination of wheat(Triticumaestivum) seeds under salinity stress as plant growth promoting bacteria (PGPB). However, most of them lost the germination promoting effects when salinity stress was revoked. Interestingly, the proportion of P GPB on all endophytes exhibited a marked escalating trend along with the increase of bacterial salt tolerance, which suggested there was a relationship among environmental salt stress, bacterial salt tolerance and bacterial plant growth-promoting (PGP) ability.23strains which could influence the growth of wheat seedings was selected to check the producing of PGP related metabolites, including indole auxin, ACC daminase, siderophore, phosphate solubilizing ability, acetoin and nitrogen fixation. The results show there is no necessary link between bacterial PGP characters and its ability to promote germination of wheat seeds under salt stress. During the further plant experiment,2of the23strains exhibited significant promotion to the growth of wheat under salt stress. They were identified to Bacillus sp. and Pseudomonas sp., and both of them can produce indole auxin.