Balancing growth and stress tolerance helps plants survive unfavorable environments such as hypoxia caused by submergence. However, the underlying mechanisms by which plant cells fine-tune growth and responses to hypoxia remain unclear. Here, we identified an Arabidopsis (Arabidopsis thaliana) RELATED TO APETALA2 (RAP2) transcription factor, RAP2.4h, that functions in controlling the energy-signaling-mediated trade-off between growth and tolerance of hypoxia. The Arabidopsis RAP2.4h knockout mutant showed increased tolerance of hypoxia and reduced vegetative growth; transgenic lines overexpressing RAP2.4h (RAP2.4h-OE) showed decreased tolerance of hypoxia with increased vegetative growth. During hypoxia, the α-catalytic KIN10 subunit of the energy sensor SnRK1 interacted with and phosphorylated RAP2.4h, thereby suppressing RAP2.4h transcription. Under normoxic conditions, RAP2.4h directly targeted the promoters of the aquaporin genes PIP2;1 and PIP2;2, stimulating their expression. Loss of PIP2;1 and PIP2;2 function rescued the hypoxia hypersensitivity and excessive vegetative growth of RAP2.4h-OE lines. Analyzing the hypoxia sensitivity and growth phenotypes of OsRAP2.4h-knockout mutants in rice (Oryza sativa) revealed functional conservation of the RAP2.4h-PIP2 module in rice and Arabidopsis. Thus, this work uncovers a genetic link connecting energy signaling with the hypoxia response and demonstrates that the SnRK1-RAP2.4h-PIP2 module functions to balance growth and hypoxia tolerance in plants.
Liao et al. (Thu,) studied this question.