3种胡枝子抗氧化酶和渗透调节物质对干旱和增强UV-B辐射的动态响应

为探究干旱和增强UV-B辐射对3种胡枝子(美丽胡枝子、二色胡枝子、牛枝子)抗氧化酶活性和渗透调节物质的影响,采用盆栽试验,研究了正常生长(CK)、干旱胁迫(D)、增强UV-B辐射(UV-B)及二者复合胁迫(D+UV-B)下各植物叶片中抗氧化酶活性和渗透调节物质的动态响应.结果表明:3种处理下各植物叶片中SOD活性较对照值均呈先下降后上升趋势,且与单因子处理相比,牛枝子和二色胡枝子在复合胁迫下其SOD活性更高；增强UV-B辐射和复合处理下POD活性随胁迫时间总体呈先上升后下降趋势；CAT活性在干旱和复合胁迫下高于对照值,而在增强UV-B辐射下较对照值有所下降.3种植物叶片渗透调节物质含量(可溶性蛋白、可溶性糖、游离脯氨酸)在各处理中较对照值均有所增加,并呈先上升后下降趋势,但种间差异显著.3种处理均导致各植物叶片内MDA含量不同程度的升高,升高幅度的大小依次为牛枝子＞美丽胡枝子＞二色胡枝子.通过隶属函数法综合评价得出,复合处理下二色胡枝子和美丽胡枝子具有较强的抗氧化能力,牛枝子抗氧化能力较弱.综上,与干旱胁迫和增强UV-B辐射相比,复合胁迫对植物的伤害程度更小,说明干旱与增强UV-B辐射可以相互缓减彼此对植物的伤害,且美丽胡枝子和二色胡枝子在抵抗干旱胁迫和增强UV-B辐射方面具有一定优势.

Dynamic response of antioxidant enzymes and osmotic adjustment substances to drought and enhanced UV-B radiation in three Lespedezas

The present work studied the effects of drought and enhanced UV-B radiation as well as their combined stress on antioxidant enzymes and osmotic adjustment substances in three Lespedezas species. Superoxide dismutase (SOD) activity decreased firstly and then increased under all kinds of stress in all three species, and the combined stress of drought and enhanced UV-B radiation increased SOD activity more substantially than the single factor stress does in L. potaninii and L. bicolor. In all three species, peroxidase (POD) activity firstly increased, and then decreased under enhanced UV-B radiation and its combination with drought stress. Catalase (CAT) activity of three species increased under both the drought and the combined stress, but decreased under enhanced UV-B radiation, compared with their controls value. In addition, the content of osmotic adjustment substances (soluble protein, soluble sugar, soluble proline) in three Lespedezas increased first, and then decreased compared with their controls value, but significant inter-species differences were observed. Generally, a significant increase of malondialdehyde (MDA) content was observed under stress conditions, and it increased more in L. potaninii than in L. bicolor and L. formosa when compared with their control values. These results suggested that the damage caused by the combined stress of enhanced UV-B radiation and drought was less than that caused by UV-B radiation or drought alone stress, which means there existed a cross adaptive phenomenon between draught stress and enhanced UV-B radiation in Lespedezas. Finally, a comprehensive evaluation on antioxidant defense capacity of different species was given according to subordinate function values analysis. L. formosa and L. bicolor with higher antioxidant capacity were more tolerant than L. potaninii to the stresses provided in this experiment.