Contrasting strategies of two Camellia oleifera cultivars in shaping arbuscular mycorrhizal fungi communities under different phosphorus forms

Phosphorus (P) availability regulates the arbuscular mycorrhizal fungi (AMF) symbiosis, but the distinct effects of different P forms (soluble, insoluble, organic) and host plant genotypes on AMF communities remain underexplored. Using Camellia oleifera cultivars with contrasting P-use efficiencies (low-P-sensitive CL3 and low-P-tolerant CL40), we examined how P forms and cultivar identity shape AMF communities and their functional linkages to plant growth and soil nutrients. The results showed that soluble inorganic P (SP) maximized plant height and biomass but suppressed AMF diversity and simplified co-occurrence networks. In contrast, insoluble inorganic P (IP) enhanced AMF colonization rates and stabilized microbial interactions. The low-P-sensitive CL3 hosted a higher Chao1 index under P limitation, suggesting compensatory recruitment for P acquisition, while CL40 exhibited stronger soil P activation and maintained complex AMF networks. Glomus and Paraglomus were identified as core taxa in the rhizosphere AMF networks of C. oleifera. RDA and Mantel analyses showed that variation in plant growth and root traits was aligned with AMF characteristics, particularly colonization and core taxa (Glomus, Paraglomus), and strongly associated with soil nutrients, with SP treatment reducing mycorrhizal dependence and shifting associations toward Paraglomus. These insights inform targeted cultivar selection and phosphorus management to optimize C. oleifera production and maintain soil health.