A Mycorrhiza-Induced Phosphate Transporter <i>TaPT31-7A</i> Regulating Inorganic Phosphate Uptake, Arbuscular Mycorrhiza Symbiosis, and Plant Growth in Wheat

Phosphate transporters play a key role in improving crop yield. In this study, TaPT31-7A is a high-affinity phosphate transporter strongly induced in arbuscular-mycorrhizal (AM) wheat roots. It restores Pi uptake in yeast mutant MB192 and localizes to the plasma membrane. TaPT31-7A overexpression lines accumulated more shoot and root phosphorus than the wild type under both low- and high-Pi conditions. When inoculated with AM in Pi-deficient soil, these overexpression lines displayed enhanced Pi uptake, higher mycorrhization, and improved growth, ultimately increasing the spikelet number per spike, spike length, 1000-grain weight, grain length, and grain width. Transcriptome and coexpression analyses of TaPT31-7A OE lines and control plants showed altered expression of phosphate-starvation and AM-development genes, while docking and yeast two-hybrid assays confirmed its interaction with PP2C phosphatase TaPP2C12-6A. These results establish TaPT31-7A as a central regulator of Pi uptake, AM symbiosis, and productivity in wheat and highlight its potential for breeding phosphorus-efficient cultivars.