ZmCCT regulates drought tolerance in maize by interacting with ZmFra a 1, E3 ligase ZmWIPF2 and auxin response factor ZmAux/IAA8.

Abiotic stressors are widespread in plants and can affect their growth, productivity, and quality. Previously, the maize transcription factor ZmCCT was been proved to be involved in the photoperiod response, delayed flowering and quantitative resistance to Gibberella stalk rot. In this study, we demonstrate that ZmCCT can regulate plant drought stress. ZmCCT physically interacted with ZmFra a 1, ZmWIPF2, and ZmAux/IAA8, which localised to the cytomembrane, cytoplasm, and nucleus, respectively, both in vitro and in vivo in a yeast two-hybrid screen in response to abiotic stress. Notably, ZmCCT recruits ZmWIPF2 to the nucleus, which has strong E3 self-ubiquitination activity dependent on its RING-H2 finger domain in vitro. When treated with higher indole-3-acetic acid (IAA)/abscisic acid (ABA) ratios, the height and root length of Y331-ΔTE increased, and this resulted in an increase in auxin and ABA tolerance. In vivo, ZmCCT promoted IAA biosynthesis in ZmCCT-overexpressed Arabidopsis. RNA-seq and DAP-seq analyses showed that ZmCCT can regulate the expression of ZmRD17, ZmAFP3, ZmPP2C and ZmARR16 under drought stress. Our finding provides a detailed overview of the molecular mechanism controlling ZmCCT functions and highlights that it HAS multiple roles in promoting stress tolerance.