A bidirectional phosphate transporter relieves phosphate limitations of photosynthesis to improve grain yield in rice

Abstract

Abstract Phosphate (Pi) plays an essential role in plant photosynthesis, although the mechanism by which Pi availability is regulated in photosynthesising leaves remains largely unknown. Here, experiments in rice (Oryza sativa L.) demonstrated that the bidirectional phosphate transporter OsPHO1;2 allocated Pi toward the leaves, thus optimizing photosynthesis, especially during grain filling. Ospho1;2 mutants showed decreased Pi concentrations in the leaves, which disrupted photosynthetic protein expression and phosphorylation levels; photosynthetic metabolite accumulation, electron transport activity, and the CO2 assimilation rate were also decreased compared with wild-type plants, resulting in earlier occurrence of Pi-limited photosynthesis. In contrast, OsPHO1;2 overexpression greatly increased Pi availability and therefore photosynthetic rates in leaves during the grain-filling stage. Analysis of germplasm resources in rice accession collection revealed that higher OsPHO1;2 expression was associated with enhanced photosynthesis and yield potential compared to those with lower expression. Moreover, foliar application of phosphate fertilizer at the flowering stage markedly increased photosynthetic rate and grain yield. These findings establish an effective strategy for achieving high photosynthetic efficiency in crop breeding with sustainable application of phosphate resources.