Study On The Microbial Community In Rhizoplane And Root Zone Soil Of Root Rot Diseased And Healthy Plants Of Lycium Barbarum In Ningxia

Lycium barbarum is a traditional Chinese herbal medicine with high nutritional and medical values.It is an important economic crop with a long cultivation history in Ningxia.Root rot is common during Lycium barbarum cultivation,resulting in a significant decline in the yield of Lycium barbarum and serious damages.The change of soil microbial community is proved to be closely related to the occurrence of root rot of plants.However,existing research on microbial community of root rot of Lycium barbarum is very limited.In order to understand the relationship between root rot of different varieties of Lycium barbarum and soil microbial community in rhizoplane and root zone,samples from healthy and root rotten plants of three cultivated varieties were chosed as research materials.Based on the practical investigation of the planting situation in Zhongning,Ningxia,soil samples and root tissues of HBW Ningqi-1 from Huabao Bay,Zhongning County,QT Ningqi-5 and QT Ningqi-7 from Enhe Town,Zhongning County were collected.Using high-throughput sequencing technology,the diversity and community composition of rhizoplane microorganisms and root zone soil microorganisms of healthy and diseased plants were analyzed and compared.The main results are as follows:(1)The richness and diversity of microbial community on the rhizoplane of healthy plants of HBW Ningqi-1,QT Ningqi-5 and QT Ningqi-7 were greater than those of the corresponding diseased plants,among which the maximum value of species richness and diversity was in the samples of Ningqi-1,followed by Ningqi-7.The minimum value of species richness and diversity was in the samples of Ningqi-5.(2)There were great differences in fungal community and bacterial community between healthy and diseased plants of different cultivated varieties of Lycium barbarum,among which the community composition of microorganisms on the rhizoplane showed the biggest difference.(3)In all the samples,the dominant phyla of bacterial community were Proteobacteria,Actinobacteria and Chloroflexi,and the dominant genera were Arthrobacter and Rhizobium.In the root-zone soil of healthy and diseased plants,there was not much difference in bacterial abundance at phylum level.The abundance of Proteobacteria and Actinomycetes on the rhizoplane of diseased plants was higher than that of healthy plants,while the abundance of Chloroflexi was lower than that of healthy plants.(4)In the diseased plants of QT Ningqi-5 and QT Ningqi-7,the species composition and abundance of the fungi in rhizoplane was tend to be consistent,with the most dominant phylum being Ascomycota,accounting for more than 97%,followed by Mortierellomycota.The composition and abundance of dominant species were quite different in the healthy rhizoplane of the Ningqi-5 and Ningqi-7.The abundance of Ascomycota(73.2%)in the rhizoplane of Ningqi-7 was much lower than that of Ningqi-5(81.5%),and the second dominant phylum was Basidiomycota.Compared with Ningqi-7,the composition of fungal community in the healthy rhizoplane of Ningqi-5 was closer to that in the diseased rhizoplane,which might be one of the reasons for the most susceptible of Ningqi-5 to root rot.(5)Ascomycota was the most dominant phylum in all the samples of healthy and diseased plants,and its abundance was as high as 56.5%?97.9%.The main dominant genera were Fusarium,Mortierella and Alternaria.Except for the rhizosphere soil of QT Ningqi-5,the abundance of Ascomycetes in the samples of the diseased plants was significantly higher than that of the healthy plants.In all the rhizoplane and rhizosphere samples of the diseased and healthy plants,the abundance of Fusarium in the rhizoplane and rhizosphere of different cultivated varieties of diseased plants was significantly higher than that of the corresponding healthy plants,while the abundance of Mortierella was significantly lower than that of corresponding healthy plants.In summary,the change of relative abundance of Fusarium and Mortierella might be closely related to the occurrence of root rot.The relative abundance of Fusarium and Mortierella in rhizoplane and rhizosphere microorganisms can be used to forecast whether Lycium barbarum was infected with root rot.