La(Ⅲ)对UV-B辐射胁迫下大豆幼苗类黄酮清除自由基影响

Effect of Lanthanum on Flavonoid Restraining Free Radical in Soybean Seedling under Ultraviolet-B Stress

为了解黄酮类化合物抗氧化构效关系,进一步论证La(Ⅲ)能经代谢调控减轻胁迫伤害。以大豆幼苗为材料,采用水培实验的方法研究了胁迫后期(5d),La(Ⅲ)对UV-B辐射胁迫下大豆幼苗类黄酮含量和类黄酮清除活性氧自由基(O2-;.OH)能力的影响,同时比较了一定浓度下不同类黄酮化合物清除自由基的能力。结果表明,类黄酮含量T1组较CK增加4.82%,T2组较CK降低1.65%;La(Ⅲ)+T1组较CK增加5.15%,La(Ⅲ)+T2组较CK降低1.63%,UV-B辐射胁迫对大豆幼苗类黄酮含量有低强度促进高强度抑致的效应;La,UV-B,La(Ⅲ)+UV-B处理组羟基自由基清除率较CK,增幅分别为La(Ⅲ)(3.02%),La(Ⅲ)+T2(2.55%)>T2(-3.68%),La(Ⅲ)+T1(2.36%)>T1(1.13%)。La(Ⅲ),UV-B,La(Ⅲ)+UV-B组超氧基清除率较CK,增幅为La(Ⅲ)(3.16%),La(Ⅲ)+T2(39.02%)>T2(31.40%),La(Ⅲ)+T1(13.95%)>T1(5.58%),La(Ⅲ)可在一定程度上提高大豆幼苗类黄酮含量,增加类黄酮清除自由基能力,减轻UV-B辐射对大豆幼苗伤害。类黄酮清除自由基能力与其组成和构效相关;3种类黄酮清除自由基的能力是槲皮素>桑色素>芦丁。

Effects of La （ Ⅲ ） on the content of flavonoid in the soybean （Clycine max） seedlings and the ability of removing free radicals （O2-;OH） by flavonoid under elevated ultraviolet-B radiation （UV- B,280nm- 320nm） were studied in the late phase of stress （5d）. And the ability of removing free radicals by different flavonoid compounds was contrasted. The purposo was to understand the role of flavonoid in antioxidation, and then to prove that La （Ⅲ） could alleviate the damage of stress by regulating the metabolism. The results showed that UV-B stress at low dose （0.54kJ·h^-·m^-2） increases the content of flavonoid which is decreased by UV-B stress at high dose （1.62kJ·h^-·m^-2）. Lanthantml （20mg·L^-1） could increase the content of flavonoid in soybean seedlings, enhance the ability of removing free radicals by flavonoid, and then alleviate the damage of UV - B to soybean seedling. The ability removing free radicals by flavonoid relates to the composition. The results showed that the ability of removing free radicals is that quereetin is stronger than morin, and rutin is the worst.The relationship between flavonoid content and mechanism of removing free radicals by flavonoid under ultraviolet - B radiation is discussed from several angles laying the basis for future studies.