摘要PHR1(PHOSPHATE STARVATION RESPONSE1)plays key roles in the inorganic phosphate(Pi)starvation response and in Pi deficiency-induced anthocyanin biosynthesis in plants.However,the post-translational regulation of PHR1 is unclear,and the molecular basis of PHR1-mediated an-thocyanin biosynthesis remains elusive.In this study,we determined that MdPHR1 was essen-tial for Pi deficiency-induced anthocyanin accu-mulation in apple(Malus × domestica).MdPHR1 interacted with MdWRKY75,a positive regulator of anthocyanin biosynthesis,to enhance the MdWRKY75-activated transcription of MdMYB1,leading to anthocyanin accumulation.In addition,the E3 ubiquitin ligase SEVEN IN ABSENTIA1(MdSINA1)negatively regulated MdPHR1-promoted anthocyanin biosynthesis via the ubiquitination-mediated degradation of MdPHR1.Moreover,the protein kinase apple BRASSI-NOSTEROID INSENSITIVE2(MdBIN2)phos-phorylated MdPHR1 and positively regulated MdPHR1-mediated anthocyanin accumulation by attenuating the MdSINA1-mediated ubiquitina-tion degradation of MdPHR1.Taken together,these findings not only demonstrate the regu-latory role of MdPHR1 in Pi starvation induced anthocyanin accumulation,but also provide an insight into the post-translational regulation of PHR1.