Functional identification of the bHLH transcription factor MdSAT1 in the phosphate deficiency response

Inorganic phosphate (Pi) starvation severely affects the normal growth and development of plants. In this study, MdSAT1, a Pi-responsive bHLH transcription factor, was isolated from apples. Ectopic expression of MdAST1 in Arabidopsis increased the number of lateral roots and root tips, as well as the transcript levels of genes related to Pi uptake and transport; thus, improving Pi utilization in response to a Pi deficiency. Ectopic expression of MdSAT1 significantly accelerated flowering and leaf senescence in Arabidopsis under a Pi deficiency. Taken together, the present study provides a basis for an in-depth investigation of the mechanisms of MdSAT1 on apple Pi uptake and utilization as well as plant growth and development.