Ectomycorrhizal Symbiosis Enhances Mineralization of Phytate by Inducing Host‐Derived Purple Acid Phosphatase Secretion in Castanea henryi

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Plant symbiosis with ectomycorrhizal fungi (ECMF) promotes soil phosphorus (P) uptake, and studies have suggested that acid phosphatase (ACP) produced by ECMF promotes soil organic phosphorus (Po) mineralization and thus aids in plant P uptake. However, how the host plant plays a role, if any in this process, is not clear. We explored the response of the host plant, Castanea henryi, to phytate and its utilization mechanism after inoculation with Pisolithus orientalis LY-8. In this study, ECMF inoculation significantly enhanced plant biomass, and soil available phosphorus, labile organic phosphorus, moderately labile organic phosphorus content, and Po mineralization rate. After inoculation, the ACP activity of plant root tips was higher than the sum of the ACP secreted by uninoculated root tips and the ACP secreted by fungi. Besides, alkaline phosphatase, and root tip vigor were significantly increased after inoculation. Transcriptome sequencing and RT-qPCR revealed that the relative expression of ChACP genes, especially purple acid phosphatase (ChPAPs) and phosphorus transporter genes were significantly higher in the inoculated treatment than in the uninoculated treatment. These results indicate that ECMF can induce the expression of ChPAPs, thus affecting the secretion of ACP in the root system of C. henryi, which in turn strengthens the ability to mineralize soil Po and promotes plant growth. Our results provide new insights into the understanding of the mechanisms of the role of ECMF in plant P nutrient acquisition.