Suppression of TaHDA8-mediated lysine deacetylation of TaAREB3 acts as a drought adaptive mechanism in wheat root development

Wheat root systems undergo dynamic and adaptive changes to mitigate the adverse effects through elaborate regulatory mechanisms under drought stress. Elucidating and utilizing these mechanisms is highly important for breeding drought resistant wheat varieties. Here, we identify histone deacetylase TaHDA8, as a critical component in regulating wheat root elongation and drought resistance. Under drought stress, TaHDA8 can be finely tuned to alleviate its inhibition of root elongation, thereby adapting to water deficit. Interestingly, the reduction in TaHDA8 protein levels restores the DNA-binding ability of TaAREB3, a positive regulator of root elongation and drought resistance, which depends on the retention of acetylation at K248 and K281 residues. The restored DNA-binding ability of TaAREB3 activates the expression of TaKOR1, thus promoting root elongation by regulating cell proliferation in the root meristem. Further studies reveal that natural variations in the TaKOR1 promoter determine the differences in TaAREB3 binding, and wheat germplasm with TaHDA8-TaAREB3-TaKOR1 regulatory module has been widely selected. Overall, this study reveals how lysine deacetylases regulate drought-responsive root development via non-histone deacetylation, providing genetic resources for improving root architecture and breeding drought-resistant wheat.