La(Ⅲ)对UV-B辐射胁迫下大豆幼苗内源激素的影响

Effect of Lanthanum on the Endogenous Hormone in Soybean Seedlings under Ultraviolet-B Stress

为了探索La(Ⅲ)对UV-B辐射胁迫下大豆幼苗内源激素的影响,试验以大豆幼苗为材料,采用水培实验的方法研究了La(Ⅲ)对UV-B辐射胁迫下大豆幼苗生长素(IAA)、生长素氧化酶(IAAO)、脱落酸(ABA)、赤霉素(GA)的影响。结果表明,UV-B辐射(T1:0.15W.m-2和T2:0.45W.m-2)胁迫下,大豆幼苗IAA、IAAO、ABA、GA含量在胁迫期(1d～5d)和恢复期(6d～11d)分别呈现"先下降后有所回升"、"先升后降再升"、"先升后降"、"下降"趋势。而各处理组IAA和GA含量La(Ⅲ)+UV-B>UV-B,La(Ⅲ)>CK,La(Ⅲ)+T1>La(Ⅲ)+T2;IAAO活性和ABA含量恰与之相反。表明La(Ⅲ)可减缓UV-B辐射对大豆幼苗的伤害,且对低剂量(T1)的防护效果优于高剂量(T2),进而在防御系统层面实现了La(Ⅲ)对UV-B辐射伤害大豆幼苗的防护效应。

In order to explore the effect of lanthanum（La）（Ⅲ） on the endogenous hormone of soybean seedlings under elevated ultraviolet-B radiation（280–320 nm）,the effects of La（Ⅲ） on the contents of indole-3-acetic acid（IAA）,abscisic acid（ABA） and gibberellic acid（GA）,and the activity of acetic acid oxidase（IAAO） under elevated ultraviolet-B radiation were investigated using the method of hydroponics culture.The results showed the content of IAA in soybean seedlings with UV-B treatment（T1：0.15W/m2;T2：0.45W/m2） during the stress（1st to 5th day） and convalescent period（6th to 11th day） was decreased initially and then increased,compared with the control.The change in the activity of IAAO with the treating time followed the order： ＂increase-decrease-increase＂.A similar change in the content of ABA in soybean seedlings occurred.The content of GA decreased during the experiment compared with the control.In addition,the contents of IAA and GA in soybean seedling treated with La（Ⅲ） were higher than that of the control,while the opposite effect was observed in the activity of IAAO and the content of GA in soybean seedlings.The contents of IAA and GA in soybean seedlings with La（Ⅲ） ＋ UV-B treatment were higher than those of UV-B treatment,while the opposite effect was observed in the activity of IAAO and the content of GA in soybean seedlings.Meanwhile,the effect of La（Ⅲ） on the endogenous hormone in soybean seedling exposed to T1 was more obvious than that of T2.Our data suggested that La（Ⅲ） of the optimum concentration could protect soybean seedling from the damage induced by UV-B stress by regulating the content of endogenous hormone in soybean seedling.Moreover,the protective effect of La（Ⅲ） against the low level of UV-B radiation is superior to that of the high level of UV-B radiation.Further,the defensive effect of La（Ⅲ） on soybean seedlings under UV-B stress is carried out on the layer of defense system.