外源NO对PEG胁迫下苜蓿幼苗抗氧化酶及同工酶的影响

Effects of Exogenous NO on Antioxidant Enzymes and Isozymes in Alfalfa Seedlings under PEG Stress

为研究外源NO对聚乙二醇-6000(PEG)拟干旱胁迫下紫花苜蓿抗氧化酶活性及其同工酶的影响。本试验用一氧化氮供体硝普钠(SNP)或一氧化氮清除剂c-PTIO对干旱胁迫下紫花苜蓿幼苗进行处理,并采用分光光度法和聚丙烯酰胺凝胶电泳技术对抗氧化酶及其同工酶研究。结果表明:SNP+PEG处理能显著提高紫花苜蓿幼苗的地上部干重和根干重,分别增加了100.00%、61.54%;而不同处理的SOD、POD、CAT活性都随着处理时间的延长呈现先升高后降低的趋势,在处理的第4天,SOD、CAT活性达到最大值,在处理的第6天,SOD活性达到最高。在处理的第4天,SNP+NO处理POD活性降低了32.18%,而POD、CAT活性升高了9.81%、43.37%,说明SNP能够通过不同程度影响抗氧化酶活性而缓解PEG对紫花苜蓿的氧化损伤。PEG+c-PTIO则抑制了紫花苜蓿幼苗的抗氧化酶活性。不同时间各处理紫花苜蓿幼苗POD同工酶都呈现9条酶带,其中P1、P5、P6酶带不同处理之间酶活性明显不同;SOD同工酶在处理过程中产生相对迁移率分别为0.610、0.470和0.345的3条酶带。PEG+SNP处理酶带颜色较深。而CAT同工酶形成了两条相对迁移率分别为0.322、0.259的酶带,各处理之间无明显的变化。说明外源SNP能有效的缓解PEG对紫花苜蓿幼苗造成的氧化损伤,促进植物的生长。本研究结果为紫花苜蓿的耐旱生理机制研究提供了一定的科学依据。

In order to study the effects of exogenous NO on antioxidant enzyme activities and isozymes of Medicago sativa under the drought stress of polyethylene glycol-6000(PEG). This experiment used nitric oxide donor sodium nitroprusside(SNP) or nitric oxide scavenger c-PTIO to treat alfalfa seedlings under drought stress, and used spectrophotometry and polyacrylamide gel electrophoresis to study the antioxidant enzymes and their isozymes. The results showed that SNP +PEG treatment could significantly increase the aboveground dry weight and root dry weight of alfalfa seedlings, which increased by 100% and 61.54%, respectively, while the activity of SOD, POD and CAT in different treatments increased first and then decreased with the prolongation of treatment time. At 4 d of treatment, the activity of POD and CAT reached the maximum value. At 6 d of treatment, the activity of SOD reached the highest. On the 4 d of treatment, SNP+NO treatment decreased POD activity by 32.18%,while SOD and CAT activities increased by 9.81% and 43.37%, it indicated that SNP can alleviate the oxidative damage of PEG to alfalfa by affecting the activity of antioxidant enzymes to varying degrees. PEG+c-PTIO inhibited the antioxidant enzyme activities of alfalfa seedlings. The POD isozyme of alfalfa seedlings treated at different time showed 9 enzyme bands, and the enzyme activities of P1, P5 and P6 under different treatments were different.3 enzyme bands were produced in the process of treatment of SOD isozyme and the relative mobility was 0.610,0.470 and 0.345, respectively. The color of the enzyme band in PEG +SNP treatment was deeper. CAT isozymes formed two bands with relative mobility of 0.322 and 0.259, respectively. There was no significant change among the treatments. The results showed that exogenous SNP could effectively alleviate oxidative damage caused by PEG to alfalfa seedlings and promote plant growth. The results would provide a scientific basis for the physiological mechanism of drought resistance in alfalfa.