ABF1 Positively Regulates Rice Chilling Tolerance via Inducing Trehalose Biosynthesis

Chilling stress seriously limits grain yield and quality worldwide. However, the genes and the underlying mechanisms that respond to chilling stress remain elusive. This study identified ABF1, a cold-induced transcription factor of the bZIP family. Disruption of ABF1 impaired chilling tolerance with increased ion leakage and reduced proline contents, while ABF1 over-expression lines exhibited the opposite tendency, suggesting that ABF1 positively regulated chilling tolerance in rice. Moreover, SnRK2 protein kinase SAPK10 could phosphorylate ABF1, and strengthen the DNA-binding ability of ABF1 to the G-box cis-element of the promoter of TPS2, a positive regulator of trehalose biosynthesis, consequently elevating the TPS2 transcription and the endogenous trehalose contents. Meanwhile, applying exogenous trehalose enhanced the chilling tolerance of abf1 mutant lines. In summary, this study provides a novel pathway ‘SAPK10-ABF1-TPS2’ involved in rice chilling tolerance through regulating trehalose homeostasis.