[目的]揭示大豆酚类物质对O3浓度升高的代谢机制与响应方式,为从分子水平研究植物次生代谢对O3胁迫的适应机制奠定基础.[方法]以大豆(Clycine max.)为试材,O3浓度45 nmol·mol(-1)为对照,利用开顶式气室系统探讨O3浓度升高(O3-1处理:(80±10)nmol·mol(-14),O3-2处理:(110±10)nmol·mol(-1))对大豆酚类物质含量及抗氧化能力的影响.[结果]在大豆整个生育期内,O3-1处理下的大豆叶片总黄酮含量、总多酚含量及苯丙氨酸解氨酶(PAL)、脂氧合酶(LOX)、多酚氧化酶(PPO)活性与对照相比显著(P<0.05)升高,而O3-2处理下的总黄酮含量与PAL活性显著(P<0.05)低于对照.臭氧胁迫下大豆叶片超氧阴离子(O2-)产生速率和过氧化氢(H2O2)含量升高,相对电导率及丙二醛含量增加.[结论]O3浓度升高在一定程度上可以激活大豆叶片PAL和LOX等酶的活性,有利于酚类物质的合成,提高大豆的抗氧化能力,但长时间高浓度O3将导致抗氧化系统氧化损伤,从而使膜脂过氧化程度加重,对大豆表现为伤害效应.%[Objective] The objective of this experiment is to reveal the effects of phenolic substance contents and PAL, LOX activities in soybean leaves under elevated O3 concentrations, which will provide a basis at the molecular level for the adaptive mechanism of secondary metabolism in plant. [Method] Open-top chambers (OTCs) were utilized to investigate the effects of phenolic compounds and antioxidant ability in soybean leaves under different O3 concentration at (80±10 nmol·mol-1 and 110±10 nmol·mol-1). [ Result] The results indicated that, compared with control, the O3 concentration at 80±10 nmol·mol-1 induced an increase (P＜ 0.05) of flavonoids content, polypbenols content and the activities of phenylalanineammonialyase (PAL),lipoxygenase (LOX), polypbenol oxidase (PPO). But the O3 concentration at 110±10 nmol·mol-1 induced an decrease (P＜0.05) of flavonoids content and PAL activity. Then superoxide anion (O-2) production rate, hydrogen peroxide (H2O2) content, relative electrical conductivity and malondialdehyde (MDA) content in soybean leaves increased under ozone stress. [ Conclusion] The activities of PAL and LOX can be activated under certain extent elevated O3 concentration, which are beneficial to the accumulation of phenolic substances as to protect the normal growth and development of soybeans. But antioxidant system can not tolerate oxidative damage caused by elevated O3 concentration, thus increasing membrane lipid peroxidation, which represents injured effects on soybean.
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