Research On AM Fungal Diversity And Function From The Rhizosphere Of Viola Philippica In Songnen Saline-alkali Grassland

Arbuscular mycorrhizal(AM)fungi live in various habitats and are wide distributed in natural saline-alkali soils.AM fungi can improve soil salinity,and soil salinity also affects the development of AM fungi.In addition,AM fungi establish symbionts with plant roots,which have certain effects on plant growth and development and stress tolerance.In saline-alkali land,AM fungi often have unique structures and may contain some strains with certain salt tolerance.According to the preliminary investigation,Viola philippica,naturally distributed in Songnen saline-alkali grassland,is an important resource for greening and ornamental in early spring in Northeast China and has a certain salinity tolerance.However,there are no reports on the diversity of AM fungi around the rhizosphere of Viola philippica.So this research focuses on AM fungal diversity of Viola philippica in Songnen saline-alkaline grassland,from which AM fungi with advantages were screened.In order to verify the contribution of dominant strains to the salt tolerance of plants,the physiological responses of Viola prionantha mediated by AM fungi to NaCl stress were analysed.Aim at developing more AM fungal resources,screening AM fungi strains with salt resistance,in order to provide a theoretical basis for the application of AM fungi in virescence of saline urban.Main results of this study are shown below:(1)Roots of Viola philippica grown in Songnen saline-alkaline land formed I-type mycorrhizal structural with AM fungi,and with high colonization rate(73.33%-96.67%).Under different soil pH conditions,the vesicule abundance and infection intensity had significant differences and positive correlation.(2)A total of 30 species of 11 genera AM fungi were isolated and identified from the rhizosphere soil of Viola philippica by morphological identification.In order to make up the defects of morphological identification,the sequences sequenced by high-throughput sequencing technology were clustered and annotated to 103 VT species of 7 genera at 97%similarity level.(3)On the basis of combination of morphological identification and molecular biology,Claroideoglomus etunicatum was identified as the dominant species in the rhizospheres of Viola philippica in Songnen saline-alkaline grassland.We analyzed the relative abundance of 103 VT sequenced by high-throughput sequencing and concluded that Glomus sp.VTX00222 was the dominant strain.(4)Claroideoglomus etunicatum(CE)and Rhizophagus irregularis(RI)were selected as strain agents on the basis of the previous research results and literatures.Viola prionantha with two true leaves were treated with inoculation of CE,RI and CE+RI and without AM(-AM),respectively,eighty days after that,Viola prionantha were treated with different concentrations of NaCl for ten consecutive days,then the roots of Viola prionantha were observed.We found that the mycorrhizas were ? type structure.The results of each infection index showed that there were differences among Viola prionantha plants inoculated with different AM fungi.Among them,RI colonization rate>CE+RI colonization rate>CE colonization rate,and the infection rate of CE treatment and CE+RI treatment gradually decreased with the gradual increase of NaCl concentration.(5)Inoculation of AM fungi(CE,RI,CE+RI)could have different effects on the physiological indexes of Viola prionantha.CE treatment could increase CAT activity and soluble protein content of Viola prionantha at different NaCl concentrations,decrease MDA concentration.RI and RI+CE treatments could increase the soluble sugar content,soluble protein content,POD activity and CAT activity at different NaCl concentrations.