The Function of LPR1 Is Controlled by an Element in the Promoter and Is Independent of SUMO E3 Ligase SIZ1 in Response to Low Phosphate Stress in Arabidopsis thaliana

In Arabidopsis thaliana, the study identified a phosphorus starvation-insensitive (psi) mutant that exhibited impaired responses to low phosphate (LP) stress, such as reduced inhibition of primary root growth and decreased anthocyanin accumulation compared to wild-type plants. The psi mutant was found to be a new allele of lpr1, with an AC-repeat element in the promoter crucial for LPR1 expression. The mutant maintained higher cell elongation and division, and showed less sensitivity to auxin treatment, suggesting LPR1's role in regulating auxin response during Pi starvation. The study concluded that LPR1 functioned independently of SUMO E3 ligase SIZ1 and that LPR1 and PDR2 had opposing roles in root growth regulation under Pi stress.