外源ABA对大蒜试管苗玻璃化发生和抗氧化系统的影响

摘要

To investigate the mechanism of exogenous ABA alleviate the hyperhydricity of garlic plantlet in vitro,we studied the effects of exogenous abscisic acid (ABA),hydrogen peroxide (H2O2) and H2O2 +ABA on hyperhydricity,accumulation and localization of reactive oxygen species,and response of antioxidant system of plantlet in vitro with garlic variety'Ershuizao'.The results showed:(1) H2O2 aggravated hyperhydricity,the hyperhydric rate was the lowest under ABA treatment,and adding ABA into media with H2O2 alleviated hyperhydricity induced by H2O2.(2) O2-· production rate and H2O2 content was the lowest under ABA treatment and the highest under H2O2 treatment.Adding ABA to the medium with H2O2 reduced the O2-· production rate and H2O2 content.(3) The activities of catalase (CAT),peroxidase (POD) and ascorbate oxidase (APX) increased at the early stage during 0-8 day of H2O2 treatment,but then antioxidant enzyme activities of CAT,APX decreased and that of POD increased slowly during 8-16 day.SOD,CAT,POD,GR and APX activities increased linearly at 0-8 d under treatment of ABA and H2O2 + ABA.Activities of SOD,CAT,POD and APX under H2O2 + ABA treatment increased and were significantly higher than those of H2O2 treatment during 8-16th day.(4) The contents of ascorbic acid (AsA) and glutathione (GSH) increased at first and decreased later,were the highest under ABA treatment and the lowest under H2O2 treatment.(5) Tissue localization results showed that O2-· and H2O2 were mainly produced in base of plantlets and tips of leaves.The accumulation of reactive oxygen species was the lowest under ABA treatment.(6) The content of malondialdehyde and membrane relative permeability under treatment of H2O2 + ABA was significant lower than that under H2O2 and control treatments.In summary,exogenous ABA can improve the antioxidant capacity of plantlets in vitro,reduce the accumulation and diffuse of reactive oxygen species,thereby inhibiting the occurrence of hyperhydricity.%以大蒜品种‘二水早,试管苗为材料,从活性氧代谢的角度研究了外源ABA、H2O2和H2 O2+ ABA处理下的试管苗玻璃化率、活性氧积累与组织定位和抗氧化系统的响应特征,探讨ABA缓解试管苗玻璃化过程的机理.结果表明:(1)外源H2O2处理可诱导大蒜试管苗玻璃化发生,外源ABA处理下玻璃化率最低,可以缓解H2O2诱导的玻璃化的发生.(2)试管苗O2-·产生速率和H2O2含量在H2O2处理下最高,在ABA处理下最低;在添加H2O2的培养基中同时添加ABA能显著减少因外源H2O2处理引起的O2-·产生和H2O2积累.(3)试管苗CAT、POD和APX活性在外源H2O2处理前期(0～8 d)均上升并显著高于对照,但其CAT、APX活性在处理后期(8～16 d)下降,其同期POD活性也增加缓慢;各抗氧化酶的活性在外源ABA与H2O2+ ABA处理前期(0～8 d)均呈直线上升趋势,而它们在H2O2+ ABA处理后期(8～16 d)均显著高于H2O2处理.(4)各处理试管苗抗坏血酸和谷胱甘肽含量随处理时间先升高后降低,并以外源ABA处理下最高,外源H2O2处理下最低.(5)试管苗O2-·和H2O2产生部位主要在基部和叶尖,且外源ABA处理下组织中ROS的积累最少.(6)在ABA+ H2O2处理下,大蒜试管苗内丙二醛含量和膜相对透性显著低于对照和H2O2处理.研究发现,外源ABA处理可有效降低大蒜试管苗的内源O2-*产生速率和H2O2含量,提高抗氧化酶活性和抗氧化物质含量,抑制活性氧在试管苗内的产生和运输,显著降低试管苗玻璃化率;外源ABA可通过增强大蒜试管苗抗氧化能力来抑制玻璃化发生.