Screening And Identification Of Halotolerant Plant-growth-promoting Rhizosphere From Suaeda In Xinjiang

Xinjiang is the largest salinized soil distribution area in the country,with a widearea and great harm.In order to alleviate the obstacles of agricultural production caused by soil salinization,understanding the structure and diversity of the bacterial and archaea community under different degrees of salinization in order to fully exploit the native salt-promoting microbial resources in Xinjiang,and lay the foundation for the development and utilization of salt-promoting micro-organisms.In order to make full use of the advantages of local microbes adapting to the local environment,this study isolated and screened the microorganisms that are salt-tolerant and can promote plant growth from the rhizosphere of Suaeda,that providing a theoretical basis for the development of microbial agents.Applying microbial agents to different salinities soil,it can improve the salt tolerance of crops,increase the yield of food crops,increase the utilization rate of salinized soil,and increase economic benefits.The main contents of this study are as follows:1.High-throughput sequencing technology analyzed the community structure and diversity of bacteria and archaea in the rhizosphere soil of Suaeda altissima(L.)Pall and Suaeda dendroides(C.A.Mey.)Moq.of different salinization degrees.2.Using the traditional cultivable method,the salt-tolerant plant growth promoting bacteria were isolated and screened from the rhizosphere soil of Suaeda by “three-stage screening system” about salt-tolerance,plate promoting screening and pot screening.Mainly results are as follows:(1)A total of 12 soil samples from two species Suaeda rhizospheres in heavy salinization and extremely salinized soil were subjected to high-throughput sequencingshowed: a total of 587418 sequences were obtained from Suaeda rhizosphere soil,including 3809 OTUs distributed in the soil samples.The aligned sequences showed that Protebacteria,Actinobacteria,Bacterioidetes,Chloroflexi and Gemmatimonadetes were the dominant phylums in all samples.Euryarchaeota was the domain phylum of archaea in rhizosphere soil of Suaeda dendroides,and Thaumarchaeota was the domain archaea in Suaeda altissima rhizosphere soil,and also the SCG genus(Soil Crenarchaeotic Group)showed more richness in Suaeda altissima.In genus level,Ralstonia,norank_f_Nitriliruptoraceae and unclassified_o_Thermoplasmatales were unique genus in Suaeda altissima rhizosphere,Arthrobacter,Nocardioides,Lysobacter and Skermanella were specific genus to the rhizosphere of Suaeda altissima rhizosphere.With the increase of salinization degree,the abundance of Halomonas increased significantly,but norank_c_Cyanobacteria and norank_f_Euzebyaceae showed trence of decline.(2)359 strains of salt-tolerant strains were obtained through the traditional cultivable method.BG-5,MH-F,GTZW50-5,1X1-3,150SS-7,1-3-3,JH1-4,JH1-7 have obvious effect on promoting Arabidopsis growth at 0 and 50mmol/L NaCl concentration,but the effects were week under 100mmol/L NaCl concentration.GTZW50-5 and MH-F increased the root length,shoot length,dry weight and fresh weight of wheat under different salinities,and the chlorophyll and proline content of wheat showed significantly increased.JH1-4,JH1-7 and 1-3-3 could sharpenly increase the proline under the content of 200 mmol/L NaCl.Both 1X1-3 and JH1-4 could promote the growth of wheat roots under salt stress.According to phylogenetic analysis,GTZW50-5 belongs to Bacillus vallismortis,150SS-7 belongs to Zhihengliuella alba,1X1-3 belongs to Staphylococcus sp.,JH1-4 belongs to Halabocillus trueper,JH1-7 belongs to Bacillus tequilensis,while MH-F and 1-3-3 sequences were aligned with Enterobacter ludwigii and Arthrobacter sp.showed that the similarity were 95.21% and 96.74%,is new species,and identified as Enterobacter and Arthrobacter,respectively.