外源ABA对短期H2O2胁迫下侧柏幼苗活性氧代谢及相关基因的影响

摘要

[目的]研究外源ABA处理对H2O2胁迫下侧柏幼苗活性氧代谢系统的影响,探讨ABA调控侧柏氧化胁迫的可能作用机制.[方法]以侧柏幼苗为试验材料,采用水培方式,研究外施低浓度(0.5 μmol·L-1)和高浓度(200μmol·L-1)ABA对100 mmol·L-1 H2O2胁迫下侧柏幼苗活性氧代谢的影响.[结果](1)100 mmol·L-1H2O2胁迫48 h显著增加了侧柏幼苗叶片过氧化氢(H2O2)、丙二醛(MDA)、谷胱甘肽(GSH)和脯氨酸含量、抗氧化物酶(SOD和CAT)活性,而可溶性蛋白含量降低.(2)相较于高浓度200 μmol·L-1 ABA,施加0.5 μmol·L-1 ABA显著减少了H2O2胁迫下侧柏幼苗H2O2和MDA的积累,进一步提高了侧柏幼苗叶片SOD、POD和CAT活性,同时促进GSH、脯氨酸和可溶性蛋白的合成.(3)100 mmol·L-1 H2O2胁迫处理48 h,侧柏幼苗叶片活性氧代谢相关基因Cu/Zn-SOD、CAT、GR、APX、MDAR和GST表达水平较对照CK均有显著性提高;正常和H2O2胁迫下侧柏幼苗外施0.5μmol·L-1 ABA相较于200 μmol·L-1更有利于提高侧柏叶片活性氧代谢相关基因Cu/Zn-SOD、CAT、GR、APX、MDAR和GST的表达量.[结论]低浓度0.5 μmol·L-1 ABA有效地增强抗氧化系统的防御能力,减弱幼苗的氧化胁迫和膜脂过氧化水平,从而降低活性氧对侧柏的伤害.%[Objective] To investigate the mechanism of exogenous abscisic acid (ABA) on regulating oxidative stress of Platycladus orientalis,the effects of reactive oxygen metabolism were studied in the leaves of P.orientalis exposed to hydrogen peroxide (H2O2) stress with the application of different concentrations of ABA.[Method] P.orientalis seedlings were exposed to 100μmol · L-1 H2O2 were treated with 0.5 and 200 μmol · L-1 ABA,and physiological indexes and expression levels of genes related to reactive oxygen metabolism were studied.[Result] (1) 100 mmol · L-1 H2O2 significantly increased the contents of H2O2,malondialdehyde (MDA),glutathione (GSH) and proline and activities of antioxidant enzymes SOD and CAT in P.orientalis leaves,while soluble protein content decreased at 48 h.(2) Compared with 200 μ mol · L-1 ABA,0.5 μmol · L-1 ABA significantly enhanced the activities of SOD,POD and CAT,and increased the contents of GSH,proline and soluble protein in H2O2-treated seedlings,accompanied by the reduction of H2O2 and MDA contents.(3) 100 mmol · L-1 H2O2 up-regulated the expression levels of Cu/Zn-SOD、CAT、APX、MDAR 和 GST genes in P.orientalis at 48 h,and moreover,the presence of 0.5 μmol · L-1 ABA further prompted the expression levels of Cu/Zn-SOD、CAT、GR、APX、MDAR and GST genes,compared with 200 μ mol · L-1 ABA under normal and H2O2conditions.[Conclusion] Low concentration of 0.5 μmol · L-1 ABA effectively enhanced antioxidant defense,reduced oxidative stress and membrane lipid peroxidation in leaves of P.orientalis under H2O2 stress,which lowered the damage of reactive oxygen species to P.orientalis leaves and improved its resistance.