Mechanism of Cold Tolerance Mediated by the GABA Synthesis Gene TaDAO in Winter Wheat

Abstract γ-Aminobutyric acid (GABA) metabolism is implicated in plant responses to low temperature, but the key genes and mechanisms in winter wheat remain unclear. In this study, using the strongly cold-tolerant winter wheat (Triticum aestivum L.) cultivar Dongnongdongmai 1 (Dn1) and the weakly tolerant cultivar Jimai 22 (J22), we identified TaDAO, a gene in the polyamine degradation pathway of GABA synthesis, as a key cold-responsive factor. TaDAO expression was markedly induced by decreasing temperature and was significantly higher in Dn1 than in J22. Overexpression of TaDAO in Arabidopsis thaliana (L.) Heynh. enhanced cold tolerance, as evidenced by higher survival rates and recovery ability under freezing stress, along with reduced relative electrical conductivity, thiobarbituric acid reaction substance, and reactive oxygen species levels, and increased proline content and antioxidant enzyme activities. Exogenous GABA treatment further induced TaDAO expression in Dongnong Dongmai 1. These findings demonstrate that TaDAO plays a critical role in cold tolerance by enhancing antioxidant capacity and osmotic adjustment, providing a potential target for improving cold tolerance in wheat.