钙-钙调素对水杨酸诱导葡萄幼苗耐热性的影响及与抗氧化的关系

Effect of Calcium-Calmodulin on the Thermotolerance Induced by Salicylic Acid in Young Grape Seedlings and Associated with Antioxidant System

研究了钙-钙调素(Ca2+CaM)对水杨酸(SA)诱导葡萄幼苗耐热性的影响,以及抗氧化酶、MDA、CaM和Pro在这一过程中的变化。结果表明:(1)外源SA可提高葡萄幼苗的耐热性,而Ca2+可促进SA对耐热性的诱导。但是,Ca2+螯合剂EGTA、Ca2+通道抑制剂La3+以及CaM拮抗剂W7对SA诱导的耐热性产生抑制作用。高温热激后,SA或SA加Ca2+处理促进叶片内CaM的积累,EGTA、La3+或W7则抑制CaM的积累。(2)高温下,SA通过维持高水平的SOD和CAT的活性,降低MDA含量来抵抗高温造成的氧化胁迫;外源Ca2+可促进SA对SOD和CAT的诱导,而EGTA、La3+或W7则产生相反的作用。高温前后,各处理叶片内的POD和APX的活性并没有明显的变化。(3)SA或SA加Ca2+处理可增加叶片中的Pro含量,并在高温下维持较高的水平。高温后,各抑制剂处理叶片中的Pro含量与对照无明显差异。结果表明,Ca2+可调控SA诱导的耐热性,而且在此过程中,要求细胞外的Ca2+穿过质膜进入胞内,并有抗氧化酶和Pro的参与。

Effect of Ca^(2+)-CaM on the thermotolerance induced by SA in young grape seedlings was studied. The levels of antioxidant enzymes, MDA, CaM, proline were measured after the treatments. The results showed that SA could induce the thermotolerance of grape seedlings and Ca^(2+) enhanced the SA-induced thermotolerance. In contrast, pretreatment with the Ca^(2+) chelator EGTA, the plasmalemma Ca^(2+) channel blocker La^(3+), which was expected to inhibit the influx of extracellular Ca^(2+)into cells, and the CaM antagonist W7 weakened the SA-induced thermotolerance. Under heat shock, pretreatment with SA or Ca^(2+)(SA+Ca^(2+)) increased the level of CaM in leaves, but EGTA (SA+ EGTA), La^(3+)(SA+ La^(3+)) or W7 (SA+W7) decreased the levels of CaM. SA pretreatment enabled seedlings to maintain higher activities of SOD and CAT, and a lower level of MDA to weaken oxidative stress induced by heat shock. Ca^(2+) pretreatment further enhanced the SA-induced increase of SOD or CAT activity, but EGTA, La^(3+) and W7 had a contrary effect. POD or APX activity of each treatment had little change before and after heat shock. In addition, pretreatment with SA or Ca^(2+)(SA+Ca^(2+)) enhanced the content of proline and kept higher level under heat shock, the level of proline in each seedling pretreated with antagonists had no obvious difference to the control. These results showed that SA-induced thermotolerance was medicated by Ca^(2+)and required the entry of extracellular Ca^(2+) into cells through plasmalemma, and was related with antioxidant enzymes and proline.