BcPHT1;9 mediates phosphate uptake and modulates root architecture in flowering Chinese cabbage

Phosphorus (P) is an essential macronutrient for plant growth and development. The absorption and transport of phosphate in plants rely on phosphate transporter-encoded proteins, named PHT1 transporters. Flowering Chinese cabbage is an important vegetable crop, while the molecular mechanisms underlying PHT1-mediated phosphate adaptation to low-phosphate stress remain poorly understood in this species. In this study, we identified 13 PHT1 transporter proteins in flowering Chinese cabbage, BcPHT1;9 was predominantly expressed in the roots and localized to the plasma membrane. Overexpression of BcPHT1;9 significantly increased total root length, surface area, and phosphorus content under low-phosphate stress, whereas silencing suppressed these traits. BcPHT1;9 thus coordinately regulates Pi uptake, phosphate homeostasis, and root architectural adaptation to sustain balanced phosphorus nutrition under phosphate-deficient conditions. BcPHT1;9 positively enhances low-Pi tolerance by coordinating phosphate uptake and root architecture in flowering Chinese cabbage.