Community Structure and Co-Occurrence Network Analysis of Bacteria and Fungi in Wheat Fields vs Fruit Orchards

Abstract

Soil microorganisms play a vital role in biogeochemical processes and nutrient turnover in agricultural ecosystems. However, the information on how the structure and co-occurrence patterns of microbial communities respond to the change of planting methods is still limited. In this study, a total of 34 soil samples were collected from 17 different fields of two planting types (wheat and orchards) along the Taige Canal in Yangtze River Delta. The distribution and diversity of bacterial and fungal communities in soil were determined using amplicon sequencing targeting the 16S rRNA gene and ITS gene, respectively. The dominated bacteria were Proteobacteria, Acidobacteriota, Actinobacteriota, Chloroflexi, Bacteroidota, and Firmicutes. The relative abundance of Actinobacteriota and Firmicutes was higher in the orchards, while Chloroflexi and Nitrospirota were more abundant in wheat fields. Ascomycota, Mortierellomycota, and Basidiomycota were the predominant fungi in both types of soils. The diversity of bacterial and fungal communities was greater in the wheat fields than in the orchards. The statistical analyses showed that pH was the main factor shaping the community structure. Moreover, high co-occurrence patterns of bacteria and fungi were confirmed in both wheat fields and orchards. Network analyses showed that both the wheat fields and orchards occurred modular structure, which mainly contained nodes of Acidobacteriota, Chloroflexi, Gemmatimonadota, Nitrospirota and Ascomycota. In summary, our work showed the co-occurrence network and the convergence/divergence of microbial community structure in wheat fields and orchards, giving a comprehensive understanding of the microbe-microbe interaction during planting methods changes.