A positive feedback loop governed by SUB1A1 interaction with Mitogen Activated Protein Kinase 3 imparts submergence tolerance in rice

Abstract

Mitogen-activated protein kinase (MAPK) signal transduction networks have been extensively explored in plants; however, the connection between MAPK signalling cascades and submergence tolerance is currently unknown. The ethylene response factor-like protein SUB1A orchestrates a plethora of responses during submergence stress tolerance in rice. In the present study, we report that MPK3 is activated by submergence in a SUB1A-dependent manner. MPK3 physically interacts with and phosphorylates SUB1A in a tolerant-allele-specific manner. Furthermore, the tolerant allele SUB1A1 binds to the MPK3 promoter and regulates its expression in a positive regulatory loop during submergence stress signalling. We present molecular and physiological evidence for the key role of the MPK3-SUB1A1 module in acclimation of rice seedlings to the adverse effects of submergence. Overall, the results provide a mechanistic understanding of submergence tolerance in Oryza sativa.