SmDREB A1-10 Is Required for SmTTF30-Mediated Hypoxia Stress Tolerance in Salix matsudana.

Abstract

Frequent flooding events induced by extreme weather significantly threaten plant growth and productivity. Salix matsudana, a willow species, demonstrates exceptional tolerance to hypoxia and submergence stress, providing an ideal model for exploring underlying molecular mechanisms. This study highlights the roles of two transcriptional factors and their interplay in enhancing hypoxia and submergence stress resilience in Salix matsudana. SmTTF30, a GT-1 trihelix transcription factor, is specifically induced under root hypoxia, with its promoter enriched in hypoxia-responsive elements. Functional analyses reveal that overexpression of SmTTF30 in Arabidopsis thaliana improves submergence tolerance, whereas its downregulation in Salix matsudana results in heightened submergence stress sensitivity. SmDREB A1-10, identified through yeast one-hybrid screening and dual-luciferase assays as an upstream regulator of SmTTF30, directly interacts with its promoter. Overexpression of SmDREB A1-10 in Arabidopsis thaliana also enhances submergence tolerance, similar to SmTTF30. Virus-induced gene silencing (VIGS) experiments confirm that silencing SmDREB A1-10 diminishes SmTTF30 expression and hypoxia-responsive gene activation, exacerbating submergence stress effects. These findings unveil a regulatory cascade involving SmDREB A1-10 and SmTTF30 in submergence stress responses, providing insights into transcriptional networks governing submergence tolerance in trees.