外源NO及反向调控PEG胁迫下苜蓿萌发种子抗氧化酶及其同工酶动态的研究

以紫花苜蓿为材料,用一氧化氮供体硝普钠(SNP)及一氧化氮清除剂c-PTIO对苜蓿种子进行浸种处理,采用分光光度法和同工酶电泳技术来研究外源NO及反向调控对PEG胁迫下紫花苜蓿抗氧化酶活性及其同工酶的影响,并探讨NO调控苜蓿种子耐旱性的生理机制。结果表明:PEG胁迫下外施0.1 mmol·L^-1 SNP,第6天时较PEG处理POD活性降低了32.72%;第4天时SOD、CAT活性较PEG处理升高了10.48%、23.60%,有效缓解了PEG对紫花苜蓿萌发中种子的氧化损伤,提高其抗氧化能力。PEG胁迫下添加 c-PTIO抑制了苜蓿萌发期的抗氧化系统活性。从同工酶的谱带数量和强弱来看,POD同工酶各区带活力均随PEG胁迫时间的延长而增加,在第2天酶带只有1条,而第4天酶带呈现9条;SOD和CAT同工酶表达量变化不显著,但酶带强弱有一定变化,S3酶带随处理时间的延长表达量逐渐减弱;CAT同工酶谱带则一直保持2条带,无明显强弱变化。因此,外源NO在PEG胁迫下紫花苜蓿萌发中抗氧化酶快速响应并在维护氧自由基代谢平衡中起重要保护作用。

Research on exogenous NO and reverse regulation to the dynamic changes of antioxidant enzymes and isoenzymes in alfalfa seed germination under PEG stress

To study the effects of exogenous NO and reverse regulation antioxidant enzyme activities and isoenzymes of alfalfa under PEG stress, alfalfa seeds were used as experimental materials, they were pretreated with nitric oxide donor sodium nitroprusside (SNP) or nitric oxide scavenger c-PTIO, the methods of spectrophotometry and isoenzyme electrophoresis were used to analyze the activities of antioxidant enzymes. The results showed that: under the PEG stress, the external application of 0.1 mmol·L^-1 SNP, the activities of POD were 32.72% lower than the PEG treatment on the 6th day; the activities of SOD and CAT were 10.48% and 23.60% higher than the PEG treatment on the 4th day respectively, so they could alleviate the oxidation damage on alfalfa seeds which caused by PEG stress. In addition, the exogenous of c-PTIO under drought stress inhibited the activity of antioxidant system during alfalfa germination stage. According to the number and intensity of isozymes, with prolonging the PEG stress time, the bands of POD isoenzymes activity increased, and only one strip on the second day, while 9 strips on the 4th day; the expression of isoenzymes of SOD and CAT were not significantly, but the strength of the enzyme band changed to some extent, the expression of S3 enzyme band was gradually weakened with prolonged the treatment time; CAT isoenzyme band had been kept at 2 bands all through, showed no significantly changes in strength. Therefore, exogenous NO rapidly responded to antioxidant enzymes during the germination of alfalfa under PEG stress and played an important protective role in the maintenance of oxygen free radical metabolism.