Effects of exogenous nitric oxide on chilling-resistance of banana seedlings.

To explore the effects of exogenous nitric oxide(NO) on chilling-resistance of banana(Musa AAA Group Cavendish cv.Brazil) seedlings,we pretreated the seedlings with 15 μmol·L-1 sodium nitroprusside(SNP) before low temperature(8℃) stress,then determined the related physiological index changes in banana seedlings at the period of chilling stress and recovering.The results showed that SNP-treated seedlings had lighter level of wilting than water-treated(control) seedlings during 8℃ low temperature stress,and recovered quickly and completely at normal temperature.Moreover,the application of 15 μmol·L-1 SNP reduced the relative membrane permeability and contents of hydrogen peroxide and MDA,increased content of soluble protein.The activities of peroxidase(POD) and ascorbate peroxidase(APX) maintained a relatively high level in SNP-treated banana at first 2 days of cold stress,and the activities of superoxide dismutase(SOD) and catalase(CAT) increased apparently at third day of cold stress.However,the activities of all above enzymes were significantly enhanced during 2 d of recover at 28℃ following 3 d of cold stress at 8℃.These results suggested that NO could induce the antioxidant enzyme activities to alleviate the oxidative damage of banana seedlings under cold stress.