Mechanism Of AM Fungi Improving The Tolerance Of Grasses In Saline-alkali Soil

Due to climate warming,reduced precipitation,and saline water irrigation,the problem of soil salinization has intensified year by year.At present,the use of halophytes to control saline-alkaline soil has attracted the attention of researchers from all over the world,but halophytes have the problems of slow growth and long restoration periods.Studies have shown that the use of salt-tolerant grasses to repair saline-alkali soil or grassland has good economic and ecological benefits.At the same time,AM fungi can significantly improve the saline-alkali tolerance of plants,but its mechanism of salt-tolerance to grasses is still relatively researched less.In this study,a greenhouse pot experiment was used to study the growth indicators,nutrient element absorption indicators,ions balance,bacterial community structure and transcriptomics regulation of Leymus chinensis Trin.Tzvel.,Agropyron cristatum(Linn.)Gaertn.,Stipa grandis P.Smirn.,Medicago sativa Linn.,Astragalus adsurgens Pall.,Puccinellia distans(Linn.)Parl.,Achnatherum splendens(Trin.)Nevski inoculated with AM fungi(F.mosseae)under saline-alkaline soil.The effect of AM fungi on improving the resistance of different grasses to saline-alkaline soil is revealed.The result shows:(1)F.mosseae has established a good symbiosis relationship with different grasses,and the mycorrhizal infection rate is between 13.08%and 31.22%.Inoculation with F.mosseae significantly increased the biomass of S.grandis,M.sativa,A.adsurgens,and A.splendens by 21.62%?233.33%,and significantly increased the K~+/Na~+and P/Na~+of L.chinensis,S.grandis,M.sativa,A.adsurgens,P.distans and A.splendens by 36.11%?311.11%,and significantly increased the P and Na~+content in the shoots and roots of A.cristatum,S.grandis,M.sativa,A.adsurgens,and A.splendens by 21.68%?500.00%and 19.98%?188.89%,respectively.(2)The inoculation of F.mosseae significantly increased the organic carbon content of the rhizosphere soil of A.adsurgens and A.splendens by 18.21%and17.96%,and the desalination rate was significantly increased by 16.89%and20.72%,respectively.The dominant bacteria in the rhizosphere soil of A.adsurgens and A.splendens are Proteobacteria(30.62%?36.68%).Inoculation with F.mosseae increased the abundance and decreased diversity of rhizosphere soil bacterial communities of A.adsurgens and A.splendens and promotes the enrichment of beneficial bacteria Shinella,Ensifer,Paracoccus,Mycobacterium,Aeromicrobium and Thalassobacillu,and improves the adaptability of A.adsurgens and A.splendens to salinized soil.(3)After inoculation with F.mosseae,102 DEGs were obtained in the shoots of A.splendens,including 27 up-regulated genes and 75 down-regulated genes;roots obtained 732 DEGs,including 564 up-regulated genes and 168down-regulated genes.F.mosseae can control hormone response regulation pathway(GO:0009725),transmembrane transport protein activity regulation pathway(GO:0015077),cell wall regulation pathway(GO:0052386)and dehydrin gene,NADPH oxidase gene,galactinol synthase gene etc,to improve the tolerance of A.splendens to saline-alkali soil.