微囊藻毒素对水稻根系生长和抗氧化系统的影响

Effects of Microcystins on Growth and Antioxidant System of Rice Roots

以水稻幼苗为材料,研究了不同质量浓度(1、100、1 000、3 000μg·L-1)微囊藻毒素(MCs)在胁迫期和恢复期对水稻幼苗根系生长、吸收活力、抗氧化系统的影响以及MCs在水稻根部的积累.结果表明,胁迫处理7 d,MCs在水稻根部的积累量与MCs质量浓度呈正相关.1μg·L-1MCs处理促进了根系生长,根系活力上升,过氧化氢酶(CAT)活性上升有效维持H2O2于正常水平;100μg·L-1MCs处理下,根系生长受抑,根系活力下降,CAT无显著变化;在高质量浓度(1 000μg·L-1、3 000μg·L-1)MCs处理下,不仅根系生长受抑、根系活力下降,且CAT活性受抑,H2O2大量积累,膜质过氧化加剧.相比胁迫期,恢复7 d后各处理组水稻根系MCs的积累量均低于胁迫期.100μg·L-1MCs处理组根系各生长指标、根系活力、丙二醛(MDA)、H2O2和CAT的变幅减小,优于胁迫期,显示出一定程度的恢复,而1 000μg·L-1和3 000μg·L-1MCs处理组,根系生长与根系活力均低于胁迫期,氧化胁迫进一步加剧,表明高质量浓度(1 000μg·L-1和3 000μg·L-1)MCs对水稻根系造成的伤害不可逆.

The effect of different concentrations( 1,100,1 000 and 3 000 μg·L- 1) of microcystins( MCs) on growth,absorb activity,antioxidant system and its accumulation in roots of rice seedlings were studied. The results show that MCs accumulation was positively correlated with MCs concentration. After the treatment with 1 μg·L- 1MCs,the root growth and activity increased. Meanwhile,catalase( CAT) activity was increased to maintain H2O2at normal levels. After the treatment with 100 μg·L- 1MCs,the root growth and activity were inhibited whereas CAT had no obvious change. High concentrations( 1 000 μg·L- 1and 3 000 μg·L- 1) of MCs not only inhibited root growth and activity,but decreased CAT activity,leading to excessive H2O2accumulation and membrane peroxidation. After a 7-day recovery,MCs accumulations in roots in all treatment groups were all lower than those measured during the stress period. For the 100 μg·L- 1MCs treated group,the inhibition on root growth and root activity,and membrane peroxidation were alleviated,better than those measured during the stress period. However,for 1 000 μg·L- 1and 3 000 μg·L- 1MCs treated groups, inhibition on root growth,root activity,and CAT activity were heavier than those during the stress period,and oxidation stress intensified further,indicating that the damage caused by high concentrations( 1 000 μg·L- 1and 3 000 μg·L- 1) of MCs on rice roots was irreversible.