Ecological dynamics of Arbuscular Mycorrhizal Fungi in wetland and aerobic rice ecosystem under subtropical humid climatic conditions in Eastern India

The obligate plant symbionts belonging to Arbuscular Mycorrhizal Fungi (AMF), are ubiquitous in agricultural soils. Their aerobic nature makes them susceptible to the anoxic conditions prevailing in waterlogged environments, as encountered in wetland rice fields. This study utilized genotypic analysis to examine changes in AMF diversity in wetland rice cultivation compared to aerobic rice cultivation. High-throughput sequencing was employed to assess the composition of operational taxonomic units (OTUs) in both ecosystems. Our findings revealed that 88.8% of OTUs were shared between aerobic and wetland rice soils, with 6.1% and 5.1% being unique to aerobic and wetland cultivation, respectively. Various AMF families, including Glomeraceae, Paraglomeraceae, Acaulosporaceae, Geosiphonaceae, and Gigasporaceae, were prevalent in aerobic rice cultivation, whereas Claroideoglomeraceae and Diversisporaceae species dominated in wetland rice cultivation. The richness of Claroideoglomus and Diversispora species showed a strong correlation with soil phosphate and potassium concentrations. Moreover, Claroideoglomus exhibited significant positive associations with glomalin concentration, acid phosphatase, and other soil biochemical properties in wetland rice. Further co-occurrence network analysis identified Paraglomus brasilianum as the keystone species in both aerobic and wetland soil. These findings underscore the significance of species keystoneness in enhancing the ecological network of AMF in rice soils and shed light on the impact of anoxic conditions on AMF genetic drift in wetland rice cultivation.