Zinc application facilitates the turnover of organic phosphorus in rice rhizosphere soil by modifying microbial communities

Aims Zn is always co-fertilized with N and P fertilizers to increase crop yield production in agriculture. Although strong interactions between Zn and P have been recognized, how Zn affects soil P transformation mediated by microorganisms is not completely clear. Methods We planted rice plants in soils with different combinations of P and Zn supply, and analyzed the P transformation, bacterial and fungal communities, enzyme activities and gene expressions in rhizosphere soil. Results Zn application promoted rice growth and P uptake, increased available P, but decreased the proportion of organic P in rhizosphere soil after Zn supply under moderate P condition. Although Zn application did not affect either bacterial or fungal diversity, it clearly elevated PSB abundances including Saccharimonadales, Sphingomonas, Flavisolibacter, Gemmatirosa, subgroup_6, and subgroup_7, but significantly decreased the abundances of pathogenic fungi Curvularia and Fusarium under moderate P condition. Furthermore, the acid phosphatase activity increased 12.70%, the phoC, phoD, ppk, and pqqc expression levels increased to 1.88-fold, 4.99-fold, 2.86-fold, and 5.07-fold, respectively, after Zn supply under moderate P condition. Conclusion Zn application could facilitate the turnover of organic P into inorganic form and improve P availability by increasing PSB abundances, acid phosphatase activity, and functional gene expression levels. This positive effect of Zn on soil P transformation strongly depended on the environmental P conditions, as no obvious changes were displayed under high P condition. Therefore, Zn co-fertilized with appropriate P is an effective strategy to enhance P availability in rice rhizosphere soil to improve plant growth and P uptake.