Diversity Analysis Of Rhizosphere Microorganisms In Soybean Under Saline Alkali Stress

With the increasing of saline alkali soil in our country and even in the world,saline alkali soil can be used as the reserve resource for sustainable utilization.It has been the focus of scholars to improve the development and efficient utilization of saline alkali soil.In the soil ecosystem,the number and quantity of rhizosphere microorganisms reflect the quality of the soil.And the quality of the soil will directly affect the growth of plants.Therefore,plants,soil,rhizosphere microorganisms interact and influence with each other.In order to determine the conduciveness of rhizosphere microorganisms to crop growth and to improve crop resistance and soil structure,we had set four different saline and alkali concentration treatments by watering saline solution(A),covering the saline soil(B)with selected wild and cultivated soybean as object of study through pot experiment.Using of DGGE technology,combined with the diversity index,evenness and analysis of principal components,sequencing of DGGE specific bands,the effects of saline alkali stress on the growth characteristics of wild and cultivated soybean was anlyzed,and the diversity of rhizosphere microbial community structure in the saline alkali environment was explored,so as to provide data support for further exploring saline alkali microbial resources.The results of this study were as follows:(1)Two kinds of saline alkali stress(A,B)and different saline alkali concentration influence soybean plant height,leaf number,diameter,and root length in underground.Under saline alkali stress,B treatment had more stress on soybean growth.Compared with the concentration of saline and alkali,wild soybean was more resistant than cultivated soybean.According to the data of the growth indicators,it was found that the appropriate concentration of saline alkali was beneficial to the growth of soybean plants.When in excess of A2 and B2 concentration,the high salinity concentration were significantly decrease the soybean plant height,leaf number,diameter,and root length in underground.(2)Through the analysis of the bacterial diversity of wild and cultivated soybean in different saline alkali environment,it was found that the appropriate saline alkali concentration increased the diversity of rhizosphere bacteria.For example,in treatment A,the Shannon index of rhizosphere bacteria was highest in wild soybean and cultivated soybean at A2 concentration;in treatment B,the Shannon index was the highest at B3 concentration of wild soybean and B1 concentration of cultivated soybean.Through cluster analysis,it was shown that saline alkali stress had a major influence on the community structure of rhizosphere bacteria.31 specific bands were sequenced to obtain homologous bacteria in the bacterial DGGE fingerprint.Among the dominant strains are: Altererythrobacter sp.?Sphingobiumsp.?Rhizobium sp.?Olivibacter soli?Sphingomonas sp.?Psychrobacillus psychrodurans?Uncultured Sphingomonadaceae bacterium etc..(3)By analyzing the diversity of fungi in wild and cultivated soybean in different saline alkali environments,the DGGE fingerprint of fungi was different in brightness and stripes due to the treatment of saline and alkali stress and the concentration of treatment,that is the diversity of rhizosphere fungi was affected by saline and alkali stress.The Shannon index of wild soybean was the highest at A2 and B3 concentration,while the evenness index of A3 and B1 was higher than that of other treatment groups.For cultivated soybean,the Shannon index was the highest at A1 and B3 concentration and the evenness index was the highest when A4 and B4 concentration.Probably due to the difference between domestication and salt tolerance of wild plants,it shows the adaptability and tolerance in different saline alkali environments.The results of cluster analysis were shown that,the treatment of saline and alkali stress was the dominant factor in the clustering of rhizosphere fungi,for example the similarity of rhizosphere fungal community structure was 0.86 at B3 and B1 concentration.17 strains were obtained by sequence analysis of some specific bands in the DGGE fingerprint of fungi,including Fusarium oxysporum ? Actinomucor elegans ? Marcelleina tuberculispora ? Marcelleina persoonii ? Uncultured Davidiellaceae clone ? Tofieldiaceae environmental sample clone?Uncultured Cystofilobasidiales?Uncultured microeukaryote clone etc..