外源NO对Cd胁迫下娃娃菜种子萌发及幼苗生长的保护效应

Protective effects of nitric oxide on seed germination and seedling growth of Brassica pekinensis under cadmium stress

为探讨外源一氧化氮(NO)对镉(Cd)胁迫下娃娃菜(Brassica pekinensis)的保护效应,采用0、50、100、200、500和1000μmol·L^(–1)的外源NO供体硝普钠(SNP)对100和200 mg·L^(–1) CdCl_2胁迫下的娃娃菜种子进行处理,分析其对种子萌发、幼苗生长及生理指标的影响。结果表明:Cd胁迫抑制娃娃菜种子萌发和幼苗生长,幼苗叶片叶绿素(Chl)和类胡萝卜素(Car)含量显著降低,丙二醛(MDA)含量和相对电导率(REC)显著上升,幼苗叶片膜脂过氧化加速。不同浓度的SNP处理,不仅能提高Cd胁迫下娃娃菜种子的发芽率、发芽势、发芽指数和活力指数,促进幼苗生长,而且能抑制MDA含量上升,降低叶片REC,增加Chl和脯氨酸(Pro)含量,增强抗氧化酶活性。外源NO可缓解Cd胁迫对娃娃菜种子萌发及幼苗生长的抑制作用,缓解Cd胁迫引起的膜脂过氧化,提高抗Cd能力,其中以200μmol·L^(–1)SNP对Cd胁迫的缓解效果较好。

To investigate the effects of nitric oxide(NO)on mitigating Cd stress on Brassica pekinensis,the seeds(under 100 and 200 mg·L^–1 CdCl2 stress)were treated with 0,50,100,200,500,and 1000μmol·L^–1 sodium nitroprusside(SNP)as an exogenous NO donor,as well as the seed germination,seedling growth,and physiological indicators of leaves were measured.The results showed that Cd stress inhibited seed germination and seedling growth,decreased chlorophyll(Chl)and Carotenoid(Car)contents,increased malondialdehyde(MDA)and relative electrical conductivity(REC),and accelerated membrane lipid peroxidation.SNP at different concentrations performed well to promote seed germination and seedling growth,and to decrease MDA content and cell membrane permeability,increase Chl,Car and proline(Pro)contents,and activate the antioxidant enzyme system in seedlings under Cd stress.It was shown that exogenous NO not only mitigated the inhibiting effects on seed germination and seedling growth and mitigated the lipid peroxidation induced by Cd stress,but also enhanced the plants resistance to Cd stress.The most optimal SNP concentration was suggested at 200μmol·L^–1.