Characteristics of Microbial Community During the Different Growth Stages of Yam (dioscorea Opposita Thunb. Cv. Tiegun)

Dioscorea opposita Thunb. cv. Tiegun yam is an important dual-purpose medicinal and edible plant that has significant economic value in China. Understanding the assembly and function of rhizosphere and endospheric microbial communities will provide new avenues to elucidate the pathogenesis and mechanisms of serious continuous cropping obstacles (CCO) in yam, as well as to develop relevant plant probiotics. However, very few studies have focused on the dynamic changes of the microbial community along with the growth stages of such root and tuber plants. In this study, we investigated temporal changes in the structure and functions of endophytic and rhizosphere communities in field yam production. Molecular analysis results showed that the Shannon abundance in the rhizosphere community increased from the seedling to the mature stages, which contrasted with the trend of the endophytic community, and the microbial community was the most complex during the expansion stage of the underground tuber. As the growth cycle was extended, the rhizospheric genera Pseudomonas, Pseudeurotium, and Alternaria, and the endophytic genera Bacillus, Delftia, and Cladosporium increased rapidly. In contrast, rhizospheric Bacillus, Mortierella, and Talaromyces and the endophytic Enterobacter, Pantoea, and Fusarium decreased significantly. Bacillus, Enterobacter, and Pantoea bacterial strains and Fusarium, Talaromyces, and Trichoderma fungal strains were isolated from the yam rhizosphere and endospheric environments. These microorganisms represented the dominant genera at different growth stages of yam. In vitro functional assays indicated that Bacillus, Pseudomonas, and Enterobacter were capable of phosphate dissolution, indole compounds production, and resistance to pathogens. The strains represented by Bacillus, Pseudomonas, and Enterobacter accounted for 54.33 %, 32.28 %, and 33.07 % of the isolated strains, respectively. Thus, these findings suggest that supplementing necessary microorganisms according to the characteristics of the microbial community at different growth stages is a potential strategy for improving the health and quality of yam.