The Community Structure And Functional Diversity Of Soil Microbes In The Rhizosphere Of Different Plants In The Anxi Extreme Arid Desert In China

In this study,the rhizosphere soils of Ephedra przewalskii,Reaumuria songarica,Sympegma regelii,Nitraria sphaerocarpa and Salsola passerina in Anxi Extreme-arid Desert National Nature Reserve in Gansu Province,China were collected in July 2015,2016 and2017.In order to provide the basis for vegetation restoration and ecosystem conservation in arid areas,we analyzed the community structure and functional diversity of soil microbes in the rhizosphere of the studied five plants and correlation with edaphic variables by using phospholipid fatty acid(PLFA)combined with Sherlock microbial identification system and BIOLOG analysis.The main results are as follows:(1)The community structure of soil microbes in the rhizosphere of different desert plants was significantly different.Total PLFA,gram-negative bacteria,gram-positive bacteria and actinomycetes were shown as E.przewalskii?S.passerina>N.sphaerocarpa>R.songarica>S.regelii;non-AMF fungi in the rhizosphere of S.regelii was significantly lower than that of other plants;AM fungi was the lowest in the rhizosphere of E.przewalskii and R.songarica.Bacteria/total PLFA was the highest in the rhizosphere of S.regelii and the lowest that of E.przewalskii,and fungi/total PLFA showed a reverse trend;gram-positive/gram-negative bacteria in the rhizosphere of S.regelii was significantly higher than that of other plants.Characterization of gram-positive bacteria 17:1 iso ?9c was the highest in the rhizosphere of E.przewalskii;characterizations of gram-positive bacteria 12:0anteiso and 13:0 anteiso,and 14:1 ?8c indicating gram-negative bacteria had the highest value in the rhizosphere of R.songarica;15:0 iso,16:1 ?9c and 18:1 ?7c 10-methyl characterizing gram-positive bacteria,gram-negative bacteria and actinomycetes,respectively,were significantly higher in the rhizosphere of S.passerina than that of other plants.(2)The average well color development(AWCD)in the rhizosphere of E.przewalskii was significantly higher than that of other plants.The utilization of carbohydrates and polymers were the most,followed by carboxylic acids and amino acids,and amines least in rhizosphere of different desert plants.31 kinds of carbon sources can be well utilized by soilmicrobes in the rhizosphere of E.przewalskii and S.regelii;the utilization of D-galacturonic acid,Tween 80,?-butanone acid,L-arginine,L-serine and putrescine were less than that of other carbon sources in the rhizosphere of R.songarica;the utilization of?-methyl-D-glucoside,D-xylose/aldopentose,D-galactoacid ?-lactone,?-butanone acid and D-malic acid were little in the rhizosphere of N.sphaerocarpa,and D-galactoacid ?-lactone was hardly used in the rhizosphere of S.passerina.(3)Total nitrogen was positively correlated with non-AMF eukaryotes,AM fungi and anaerobe,and negatively correlated with gram-positive bacteria;acid phosphatase was negatively correlated with gram-positive bacteria,and easily extracted glomalin was positively correlated with non-AMF eukaryotes.(4)Soil pH and total phosphorus were positively correlated with the utilization of carbohydrates,polymers,carboxylic acids and amines;total nitrogen and ammonia nitrogen were negatively correlated with the utilization of carboxylic acids,phenolic acids and amino acids;acid phosphatase was significantly negatively correlated with the utilization of phenolic acids and amines;total glomalin was negatively correlated with the utilization of carboxylic acids.(5)Gram-positive bacteria were positively correlated with the utilization of phenolic acids,amino acids and amines;however,there was no significant correlation between other soil microbial groups and the utilization of other carbon sources.