铜胁迫下镧对水稻幼苗生长及抗氧化酶活性的影响

EFFECT OF La^(3+) ON GROWTH AND ACTIVITIES OF ANTIOXIDANT ENZYMES IN RICE SEEDLINGS UNDER COPPER STRESS

通过液培实验,研究水稻幼苗在铜胁迫下,稀土元素镧对地上部及根系的生长、抗氧化酶(SOD和CAT)活性、脂质过氧化产物丙二醛(MDA)含量及质膜透性的影响.结果表明:水稻幼苗在铜胁迫(100 mg.l-1和200 mg.l-1CuSO4溶液)初期(0—3d),10 mg.l-1La(NO3)3能显著提高幼苗植株SOD的活性(p<0.05),提高CAT的活性,降低幼苗植株MDA的含量.随着铜胁迫时间的延长(3—9d),抗氧化酶活性逐渐下降、MDA含量逐渐升高,表明了镧的保护作用开始减弱,在后期(第9天)甚至与铜发生协同作用,加剧了铜对水稻幼苗的毒害;其中,200 mg.l-1CuSO4溶液的协同作用更为明显,幼苗植株质膜透性明显增大(p<0.05),生长受到抑制.分析表明,适量的稀土元素镧对铜胁迫下水稻生长具有一定的保护效应,但是这种效应与铜胁迫的浓度大小、胁迫的时间长短有着密切的关系.

The effects of La（NO3）3 on the growth,the activities of antioxidant enzymes（SOD and CAT）,the level of malondialdehyde MDA）and the penetrability of cell membrane in shoots and roots of rice seedlings under copper stress were evaluated by the nutrient solution culture experiment.The results showed that for the seedlings,10 mg·l^-1 La（NO3）3 could improve the activities of SOD significantly（p〈0.05）,increase the activities of CAT,and decrease level of MDA during the initial stage（0—3d） under copper（CuSO4 concentrations of 100 mg·l^-1 and 200 mg·l^-1） stress.With the time of copper stress prolonged（3—9d）,the activities of antioxidant enzymes declined gradually and the level of MDA increased gradually,suggesting that the protective effects of lanthanum were reduced.Lanthanum even could cooperate with copper at later stages（9^th d）,then copper injured rice seedlings more grievously.The synergy of La and Cu was more obvious under 200 mg·l^-1 CuSO4 stress,thus the penetrability of cell membrane was increased significantly（p〈0.05） and the growth of rice seedlings was inhibited.It was indicated that proper lanthanum concentration could be selected to enhance the copper tolerance abilities of rice seedlings,but this relieving function of lanthanum was closely correlative with the concentration and time of copper stress.