高温干旱及复水对毛竹实生苗保护酶和脂质过氧化的影响

Protection enzymes and lipid peroxidation in Phyllostachys edulis seedlings with temperature and water stresses

为探讨高温、干旱、高温+干旱复合胁迫及复水对毛竹Phyllostachys edulis实生苗保护酶、脂质过氧化的影响,以毛竹实生苗为材料,研究了适温(昼/夜温度为28℃/22℃)正常供水(田间持水量的75%,对照),适温下干旱胁迫(田间持水量的35%),高温(昼/夜温度为40℃/22℃)正常供水,高温下干旱胁迫以及干旱胁迫后复水等4个处理对毛竹实生苗叶片中抗氧化酶、过氧化氢(H_2O_2)和丙二醛(MDA)的影响。结果表明:(1)在3种胁迫处理下,超氧化物岐化酶(SOD),过氧化物酶(POD),过氧化氢酶(CAT)活性均显著上升(P<0.05),抗坏血酸过氧化物酶(APX)活性在干旱胁迫、高温干旱复合胁迫下显著上升。其中高温处理毛竹叶片SOD和CAT活性上升幅度最大;干旱处理POD活性上升幅度最大,其次为CAT,同时过氧化氢显著高于其他各处理,达278.7 nmol·g-1;高温干旱复合胁迫下POD和APX活性上升幅度最大,MDA显著高于其他各处理。(2)复水后,干旱处理下过氧化氢在复水后第1天上升,引起POD和CAT活性上升,APX活性先降后升,复水后第3天毛竹叶片MDA,过氧化氢均恢复至对照水平;高温干旱复合胁迫下SOD,POD和CAT活性持续下降,APX先下降又有回升,同时MDA持续上升,过氧化氢先下降后又升高,在复水后第3天均处于较高水平,且与干旱胁迫相比差异显著(P<0.05)。毛竹实生苗在不同胁迫下有不同的保护机制,CAT和POD分别是毛竹适应高温和干旱的主要抗氧化酶,APX和POD对复合胁迫较为敏感,SOD则在3种胁迫下均对抗膜脂过氧化起到重要作用;在一定的干旱胁迫后复水,保护酶协同作用,表现出较强的恢复能力,而高温加剧了干旱对竹苗的伤害,在高温干旱复合胁迫后复水竹苗并未得到恢复。

To determine the effects of high temperature, drought, combined high temperature and drought, and re-watering on protective enzymes and lipid peroxidation of Phyllostachys edulis seedlings, an experiment was set up with treatments： 1） optimal temperature（day 28 ℃/night 22 ℃） and normal hydration（75% of field water-holding capacity） as a control group, 2） optimal temperature and drought（35% of field water-holding capacity）, 3） high temperature（day 40 ℃/night 22 ℃） and normal hydration, and 4） combined stress followed by re-watering to determine the effects on antioxidase, hydrogen peroide（H2O2）, and malondialdehyde（MDA）. Samples were respectively collected on Day 7 after the start of treatment, and at 9：00 am on Day 0, 1,3 after re-watering, sample weight of each group is 1.0 g. Results showed that 1） With high temperature SOD activity increased the most（P〈0.01）, and with drought POD activity was greatest（P〈0.05）; after drought the H2O2 level was significantly higher（P〈0.01） than other conditions. After combined stress, POD and APX activities increased the most（P〈0.01）, and the level of MDA was higher than other treatments（P〈0.05）. 2）On Day 1 after re-watering, H2O2increased（P〈0.05） leading to an increase of POD and CAT activity（P〈0.05） with APX activity decreasing then increasing（P〈0.05）. On Day 3 after re-watering, levels of MDA and H2O2 returned to levels of the control group, but with the combined-stress treatment, SOD, POD, and CAT activities continuously decreased（P〈0.05） and APX activity and H2O2 levels decreased and then increased（P〈0.05） with MDA levels continuing to rise（P〈0.05）. On Day 3 after re-watering MDA and H2O2 were at high levels and significantly higher than those of drought conditions（P〈0.05）. Thus, the protective mechanism for Ph. edulis seedlings with high temperature was CAT, with drought was POD, and with combined-stress conditions were APX and POD, with SOD playing an important role in anti lipid peroxidation for all three stresses.