氯化钠胁迫下嫁接黄瓜叶片SOD和CAT mRNA基因表达及其活性

研究了NaCl胁迫下嫁接和自根黄瓜叶片Cu/Zn-SOD、Mn-SOD和CAT mRNA的表达与其酶活性变化及其MDA含量和电解质渗漏率变化.结果表明：在NaCl胁迫条件下，嫁接黄瓜叶片Cu/Zn-SOD mRNA、Mn-SOD mRNA和CAT mRNA的相对表达量均高于自根黄瓜，SOD、Cu/Zn-SOD、Mn-SOD和CAT活性也均高于自根黄瓜，说明与自根黄瓜相比，嫁接黄瓜叶片较高的Cu/Zn-SOD mRNA、Mn-SOD mRNA和CAT mRNA相对表达量是其维持较高Cu/Zn-SOD、Mn-SOD和CAT活性的重要原因；随着NaCl胁迫时间的延长，嫁接和自根黄瓜叶片Cu/Zn-SOD- mRNA、Mn-SOD mRNA和CAT mRNA的相对表达量均呈上升趋势，但其酶活性变化并不完全一致，说明还有其他因素参与相关酶活性的调控；嫁接黄瓜叶片MDA含量和电解质渗漏率均低于自根黄瓜，说明嫁接黄瓜具有较高的活性氧清除系统，可以减少活性氧物质的危害，提高其耐盐性.

Relative expression of SOD and CAT mRNA and activities of SOD and CAT in grafted cucumber leaves under NaCl stress.

Taking grafted and own root cucumber (Junlv No.3) plants as test materials, the changes of their leaf Cu/Zn-SOD, Mn-SOD and CAT mRNA relative expression, leaf SOD, Cu/Zn-SOD, Mn-SOD and CAT activities, leaf MDA content, and leaf electrolytic leakage under NaCl stress were studied. The results showed that under NaCl stress, grafted cucumber had a higher relative expression of its leaf Cu/Zn-SOD, Mn-SOD and CAT mRNA, and higher activities of its leaf SOD, Cu/Zn-SOD, Mn-SOD and CAT, compared with own root cucumber, which suggested that the higher relative expression of Cu/Zn-SOD, Mn-SOD and CAT mRNA in grafted cucumber leaves resulted in the higher activities of their SOD, Cu/Zn-SOD, Mn-SOD and CAT. With the NaCl stress prolonged, the relative expression of Cu/Zn-SOD, Mn-SOD and CAT mRNA in both grafted and own-root cucumber leaves had an increasing rend, but the changing trend of Cu/Zn-SOD, Mn SOD and CAT activities were not the same as that of mRNA, indicating that the activities of SOD and CAT were also regulated by other factors. The leaf MDA content and electrolytic leakage of grafted cucumber were lower than those of own root cucumber, suggesting that grafted cucumber had a higher scavenging metabolism, which could decrease oxidative damage and increase its salt-tolerance.