Sugar starvation-regulated MYBS2 and 14-3-3 protein interactions enhance plant growth, stress tolerance, and grain weight in rice

Abstract

Significance As autotrophic organisms, sugar status in plants must be constantly monitored and reacted to in order to maintain sugar homeostatic states crucial for growth regulation, environmental stress tolerance, and productivity. α-Amylase (αAmy) is the key enzyme hydrolyzing starch into sugars and is regulated by sugar levels; it is induced by sugar starvation but repressed by sugar provision. Two MYBs compete for binding to the same αAmy promoter element to regulate this process, with MYBS1 promoting and MYBS2 repressing αAmy expression. Induction of αAmy expression by suppressing MYBS2 enhances stress tolerance and productivity. Phosphorylation of MYBS2 is critical for regulating its sugar-dependent nucleocytoplasmic shuttling and interactions with 14-3-3 proteins, representing a regulatory mechanism for reversible gene expression by sugar status.