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

Abstract

Wheat root systems undergo dynamic and adaptive changes to mitigate adverse effects through sophisticated 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 that negatively regulates wheat root elongation and drought tolerance. Under drought stress, TaHDA8 could be finely tuned to alleviate its inhibition of root elongation, thereby improving wheat adaptation to water deficit. Interestingly, reduction in TaHDA8 protein levels de-represses the DNA-binding ability of TaAREB3, a positive regulator of root elongation and drought tolerance, which depends on the retention of acetylation at K248 and K281 residues. The restored DNA binding of TaAREB3 to the promoter of TaKOR1 upregulates its expression, thereby promoting root elongation by enhancing cell proliferation in the root meristem. Further studies revealed 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. Collectively, this study reveals how a lysine deacetylase regulates drought-responsive root development via non-histone deacetylation, providing genetic resources for improving root architecture and breeding drought-resilient wheat varieties.

Keywords: TaAREB3; TaHDA8; deacetylation; drought resistance; root length; wheat.