The interaction between autophagy-related gene FtATG8a and FtE2FB is involved in the drought resistance of Tartary buckwheat

• FtATG8a enhances drought resistance in transgenic Arabidopsis and Tartary buckwheat hairy roots by activating the antioxidant system and autophagy pathway. • FtATG8a co-localizes with FtE2FB in the nucleus, with this interaction contingent on the ATG8-interacting motif (EK F ED I ) on FtE2FB. • FtE2FB enhances drought stress tolerance by altering the activities of antioxidant enzymes and promoting proline accumulation in transgenic Arabidopsis . • 4) FtATG8a and FtE2FB synergistically enhance drought resistance in Tartary buckwheat. Drought significantly limits worldwide crop yields, with autophagy acting as an essential regulatory component in plant adaptation to stress. In Tartary buckwheat, while there has been evidence of autophagosome accumulation and increased levels of FtATG8a due to drought, the molecular pathways governing FtATG8a have not yet been clarified. Our research shows that overexpressing FtATG8a markedly improves drought tolerance in genetically modified plants by synchronizing the activation of autophagy, boosting antioxidant defenses (such as SOD, POD, and CAT), and promoting proline biosynthesis. Through yeast two-hybrid screening, we identified FtE2FB as a nuclear-localized partner that interacts with FtATG8a, with their interaction facilitated by a conserved ATG8-interacting motif (EK F ED I ) found in FtE2FB, which was validated using various complementary assays. Importantly, FtE2FB expression demonstrated dual induction patterns in response to drought stress and the overexpression of FtATG8a , indicating a feedback regulatory mechanism. Functional experiments showed that the solitary overexpression of FtE2FB boosts drought resistance via the modulation of the antioxidant system and increased proline levels in Arabidopsis . Additionally, the combined expression of FtATG8a and FtE2FB led to a more substantial rise in both antioxidant enzyme activity and proline content when compared to the overexpression of either FtE2FB or FtATG8a on its own under 20 % PEG6000 treatment. This study clarifies an autophagy-related regulatory network that underpins drought adaptation in Tartary buckwheat, offering valuable mechanistic insights into the coordination of stress responses and highlighting potential molecular targets for enhancing crop improvement strategies.