外源水杨酸对酸雨胁迫后龙眼幼苗生理特性恢复的影响

Effects of exogenous salicylic acid on the physiological characteristics recovery of longan seedlings under acid rain stress

以龙眼幼苗为材料,研究酸雨胁迫(pH 3.0)后不同浓度外源水杨酸(0、0.1、0.5、1.0和2.0 mmol·L-1)对龙眼幼苗生理特性的影响。结果表明:酸雨胁迫后龙眼幼苗叶片中的超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性降低,叶绿素、蛋白质和可溶性糖含量下降,丙二醛含量升高,龙眼幼苗显示出毒害效应。0.1～1.0 mmol·L-1外源水杨酸显著提高龙眼幼苗叶绿素、可溶性糖和蛋白质的含量,增强SOD、POD和CAT活性,降低丙二醛含量,减少幼苗所受氧化伤害的程度;其中0.5 mmol·L-1水杨酸处理效果最好,叶绿素、可溶性糖和蛋白质的含量分别比单独酸雨胁迫处理植株增加了62%、105%和177%,SOD、POD和CAT活性分别提高144%、440%和132%,丙二醛含量降低了35%;而2.0 mmol·L-1水杨酸却起到相反的作用。可见,低浓度水杨酸(0.1～1.0 mmol·L-1)能通过刺激龙眼抗氧化酶活性,减轻氧化胁迫,缓解酸雨胁迫后的毒害作用,而高浓度水杨酸(2.0 mmol·L-1)对龙眼幼苗的缓解作用下降。

This paper studied the effects of exogenous salicylic acid （0, 0.1, 0.5, 1.0, and 2.0 mmol·L^-1） on the physiological characteristics of longan （Dimocarpus longana ＇Fuyan＇） seedlings under acid rain （pH 3.0） stress. Under the stress of the acid rain, the seedling＇s leaf superoxide dismutase （SOD）, peroxidase （POD）, and catalase （CAT） activities as well as the leaf total chlorophyll, soluble protein, and soluble sugar contents decreased obviously, and the leaf malondialdedyde content had a remarkable increase, suggesting the toxic effect of the acid rain on the longan seedlings. Applying 0.1-1.0 mmol·L^-1 of exogenous salicylic acid improved the SOD, POD, and CAT activities and the total chlorophyll, soluble protein, and soluble sugar contents significantly, and decreased the malondialdedyde content. Low concentrations of exogenous salicylic acid reduced the oxidative damage caused by the acid rain stress, and 0.5 mmol·L^-1 of salicylic acid had the best effect. As compared with the acid rain stress alone, applying 0.5 mmol·L^-1 of salicylic acid improved the SOD, POD, and CAT activities by 144%, 440%, and 132%, and increased the total chlorophyll, soluble protein, and soluble sugar contents by 62%, 105%, and 177%, respectively, and decreased the malondialdedyde content by 35%. It was suggested that low concentrations of exogenous salicylic acid （0.1-1.0 mmol·L^-1） could alleviate the toxic effect of acid rain stress on longan seedlings via activating the seedlings leaf antioxidant enzyme activities and reducing oxidative stress, while high concentration of exogenous salicylic acid （2.0 mmol·L^-1） lowered the mitigation effect.