An RNA helicase coordinates with iron signal regulators to regulate chilling stress in Arabidopsis

Chilling stress is one of the major environmental stresses that restrains plant development and growth. Our previous study implied that there is a crosstalk between iron homeostasis and chilling stress in plants. However, whether plant iron homeostasis is involved in plant chilling tolerance is not known. In this study, we discover that the iron sensor BTS (BRUTUS) mutant bts-2 is sensitive to chilling stress, and the sensitivity is attributed to the accumulation of iron. The suppressor screening of bts-2 led to the discovery of RH24, a DEAD-box RNA helicase. RH24 accumulation is induced by low temperatures. RH24 possesses RNA helicase activity, which unwinds the key iron regulator ILR3 (IAA-leucine resistant 3) mRNA and increases the ILR3 protein level to maintain iron homeostasis under chilling stress. Our findings reveal that the chilling responsive RH24 coordinates with iron sensor BTS to regulate plant iron homeostasis to attenuate chilling stress.