砷在不同物候期香蒲中的分布及其生理影响

Subcellular Distribution and Physiological Response of Arsenic in Typha angustifolius L.at Different Phenological Stages

为研究砷(As)在挺水植物中的富集和植物的逆境适应特征,以香蒲(Typha angustifolius L.)为例,通过水培模拟实验,研究As(浓度为0、0.5、2.0、5.0、10.0 mg/L)胁迫下不同物候期(生长期、花果期、枯黄期)香蒲叶组织和亚细胞水平As的分布特征及对活性氧代谢的生理影响。结果表明:香蒲叶组织As含量随As胁迫浓度的增加呈现逐渐升高的趋势;随着香蒲的生长(生长期、花果期、枯黄期),叶组织中As含量呈现先升高后下降的趋势,As含量在生长期最高,表明生长期的香蒲对As的富集积累能力最强。在As胁迫下,随着香蒲的生长,叶细胞壁和细胞液中As的分布比例之和为63.5%~84.5%,表明细胞壁和细胞液组分是香蒲储存As的主要部位。As对不同物候期香蒲叶中过氧化物酶(POD)活性的影响与As浓度呈正相关,对过氧化氢酶(CAT)活性产生低促高抑的作用,在不同物候期,POD与CAT存在互补关系,表明香蒲通过限制As细胞壁的固持和细胞液的区隔化来降低As的毒害;超氧化物歧化酶(SOD)和丙二醛(MDA)含量随香蒲生长和As浓度增加均显著增加,表明抗氧化酶相互协作是香蒲应对As胁迫的重要策略。

To investigate the accumulation and stress adaptation characteristics of arsenic(As)in emergent plants,taking Typha angustifolius L.as an example,the distribution characteristics of As in leaf tissues and subcellular levels and its physiological effects on active oxygen metabolism of Typha angustifolius L.under As stress(0,0.5,2.0,5.0,10.0 mg/L)at different phenological stages(growth,flowering and fruiting,dry and yellow stages)were studied through hydroponic simulation experiment.Results indicated that:the content in Typha angustifolius L.leaves increased gradually with the rise of As stress concentration;With the growth of Typha angustifolius L.,As content in leaf tissue increased first and then decreased,with the highest level observed during the growth period,indicating that the strongest enrichment and accumulation ability of As in Typha angustifolius L.occurred during its growth period.Under As stress,with the growth of Typha angustifolius L.,the sum of the distribution ratio of As in the leaf cell wall and cell fluid at the subcellular level was from 63.5%to 84.5%,indicating that the cell wall and cell fluid components were the primary storage areas of Typha angustifolius L.At various phenological stages,the effect of As on peroxidase(POD)activity in Typha angustifolius L.leaves was positively correlated with As concentration,with low-promoting and high-inhibiting effects on catalase(CAT)activity.A complementary relationship between catalase and peroxidase at different phenological stages indicated that Typha angustifolius L.could reduce As toxicity by limiting As cell wall fixation and cell fluid partition.Moreover,the contents of superoxide dismutase(SOD)and malondialdehyde(MDA)increased significantly wiht the growth of Typha angustifolius L.and As concentration,indicating that the cooperation of antioxidant enzymes was an essential strategy for Typha angustifolius L.to deal with As stress.