A genome-wide identified CCCH zinc finger protein FtCCCH56 enhances drought tolerance in Tartary buckwheat

CCCH-type zinc finger proteins are emerging regulators of plant stress adaptation, yet their functions remain largely unexplored in Tartary buckwheat (TB), an important stress-tolerant crop. Here, we identified 71 FtCCCH genes and classified them into six subfamilies. Phylogenetic and expression analyses highlighted FtCCCH56, a nuclear-localized member of subfamily VI, as the gene most strongly induced under drought stress. Promoter activity assays confirmed that FtCCCH56 is activated by drought, salinity, and abscisic acid (ABA). Functional characterization in TB hairy roots and transgenic Arabidopsis thaliana demonstrated that FtCCCH56 overexpression enhances drought and salt tolerance. Overexpressing lines exhibited greater biomass, higher survival rates, and improved recovery from stress compared to the wild type. Physiological analyses revealed that FtCCCH56-overexpressed plants accumulated more proline, displayed reduced malondialdehyde contents, and maintained stronger antioxidant enzyme activity, thereby alleviating oxidative damage. Additionally, FtCCCH56 overproduction upregulated ABA-responsive genes (AtRD29A, AtRD29B, AtRAB18, AtRD22, AtKIN1, AtCOR15A), as well as genes involved in antioxidant enzyme and proline biosynthesis. This study establishes FtCCCH56 as a positive regulator of drought stress though coordinating ABA signaling, antioxidant activation, and proline-mediated osmo-protection, providing a promising candidate gene for improving crop resilience under abiotic stress.