高寒山区草本植物的保护酶系统及其在低温生长中的作用

Protecting enzyme system of herbage and its functions in the cold growing process in alpine and cold region

研究了高寒山区几种草本植物在低温生长过程中植物叶中抗氧化酶、抗氧化物和膜脂过氧化产物的变化及其作用。结果表明 ,耐寒性差、生长期短的一年生植物微孔草 MDA含量较低 ,保护酶活力也较低。耐寒性强、生长期长的苜蓿、垂穗披碱草、草地早熟禾、无芒雀麦4种多年生植物 MDA含量较高 ,保护酶活力和抗氧化物含量也较高。其生长季平均 MDA含量分别比微孔草高 2 .2 7倍、1 .6 4倍、2 .0 7倍和 1 .5 5倍 ,超氧化物歧化酶 (SOD)活力分别比微孔草高 1 6 .7%、2 7.1 %、46 .2 %和 1 1 .5 % ;过氧化氢酶 (CAT)分别高 5 1 .5 %、1 2 3 .0 %、2 5 .3 %和 9.4% ,类胡萝卜素含量分别高 1 2 6 .5 %、1 42 .7%、1 3 8.4%和 3 94.4%。当气温低于0℃后 ,微孔草死亡 ,完成生活史 ,以种子越冬 ,在生理上无明显抗冻特征。而此时多年生植物SOD活力趋于增强 ,仍能一定生长 ,至 - 5℃～ 1 0℃低温时地上部才枯死 ,其细胞具有较强的耐膜脂过氧化能力和抗氧化酶系统 。

The changes in contents of MDA (lipid peroxidation product) and antioxidant and activities of antioxidant enzymes in leaves of annual (Sikkim microula) and several perennial grasses (Medicago sativa,Elymus nutans Griseb,Bromus inermis Leyss,Poa sphondylodes Trin) grown in alpine area were investigated during growth season to determine the role of antioxidant enzymes and antioxidant in grass adapting to grow at low temperature of alpine area.The results showed that MDA content was lower in annual grass,also several antioxidant enzyme activities were lower.Compared with annual grass,MDA content and activities of antioxidant enzymes were higher in leaves of perennial grasses.The activities of superoxida dismutase were higher in leaves of Medicago sativa,Elymus nutans Griseb,Bromus inermis Leyss,Poa sphondylodes Trin,respectively 12.32%,20.52%,5.72% and 38.68% of annual grass;peroxidase activities higher 12 times,13 times,6 times and 5 times;calase activities higher 9.6%,13.15%,9.55% and 26.12% of annual grass.Level of lipid peroxidation in leaves of grassed grown at low temperature was related to activities of antioxidant enzyme.Antioxidant enzymes play an important role in controlling the free redical accunulation in the cell,protecting cell from lipid peroxidation at low temperature.This research also indicated that there are different strategies for annual and perennial grasses to acclamation to cold growing season.Annual grass grown in the alpine only can survive at above 0℃ at which they grow fast,finish life cycle,overwintering by seeds.But perennial grasses can grow at -10℃,the antioxidant enzyme system rapidly responded to temperature changes and restricting membrane peroxidant may be key important physiological changes in perennial grasses acclimation to low temperature.