外源一氧化氮对香蕉幼苗抗冷性的影响

Effects of Exogenous Nitric Oxide on Chilling-Resistance of Banana Seedlings

以巴西香蕉(MusaAAA Group Cavendish cv.Brazil)幼苗为试验材料,采用外源一氧化氮(NO)供体硝普钠(SNP)15μmol.L-1溶液进行冷胁迫(8℃)前处理,考察其冷胁迫和常温恢复过程中抗冷性指标的变化,以探讨外源NO对香蕉幼苗抗冷性的影响。结果表明,在8℃冷胁迫环境下,SNP预处理香蕉幼苗的萎蔫程度较轻,且在常温下恢复快而完全。SNP预处理可以显著降低冷胁迫下香蕉幼苗叶片的质膜相对透性及过氧化氢和丙二醛含量,并显著增加其可溶性蛋白含量。在冷胁迫的前2 d,SNP处理苗的过氧化物酶和抗坏血酸过氧化物酶的活性显著增加,而超氧化物歧化酶和过氧化氢酶的活性则在胁迫的第3天才显著上升,经3 d冷胁迫回温(28℃)后,4种酶的活性均显著提高。可见,适当浓度NO能够通过诱导香蕉幼苗体内的抗氧化酶活性来有效缓解其遭受的冷胁迫损伤。

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.