Cold-shock-induced Chilling Tolerance And Physiological Mechanisms

1℃ is normally considered as a extreme chilling stress temperature and will cause severe chilling injury to chilling-sensitive plants. Chilling acclimation of chilling-sensitive plants was usually achieved by exposure to around or above the threshold chilling temperature (about 10℃ or 15℃) for several days. In our present work, a cold-shock treatment at 1℃ for 4 h following a 6-h recovery significantly enhanced survival percentage of maize seedlings, mitigated electrolyte leakage of primary roots and alleviated vitality loss of mesocotyls under severe chilling stress, indicating that short-term cold-shock could induce chilling tolerance of the maize seedlings. The cold-shock pretreatment brought out an endogenous H2O2 peak in maize seedlings, and enhanced the contents of antioxidants and the activities of five antioxidant enzymes (GPX, CAT, APX, GR and SOD) in maize mesocotyls. Cold-shocked seedlings demonstrated less loss in the contents of reduced antioxidants and activities of antioxidant enzymes caused by chilling stress as compared with the seedlings without cold shock. This implied that antioxidant system plays a pivotal role in cold-shock-induced chilling tolerance of maize seedlings.