为探究挺水植物对砷(As)的富集和逆境适应特征, 通过水培模拟实验, 研究As (0、0.5、2、5、10 mg·L−1)胁迫下典型挺水植物水烛(Typha angustifolia)不同物候期(生长期、花果期、枯黄期)组织和亚细胞水平As、磷(P)的分布特征及其生理响应。结果显示: (1)环境As胁迫下水烛体内As主要富集在根部, 其浓度在生长期、花果期、枯黄期分别为地上部的12.56~21.29、16.85~24.77、6.89~24.24倍; 在亚细胞水平上, 随着水烛的生长, 叶、根的细胞壁和可溶性组分中As的分布比例之和分别为69.96%~89.96%和79.72%~93.96%, 表明细胞壁和可溶性组分是水烛储存As的主要部位。(2) As胁迫浓度与水烛P转移系数呈正相关; 在亚细胞水平上, P主要分布于水烛细胞壁中, 加As处理使P趋于向细胞核和叶绿体中转移。(3)As对水烛叶抗氧化酶活性产生低促高抑的作用, 在不同物候期过氧化氢酶和过氧化物酶存在互补关系; 丙二醛含量随水烛生长和As浓度增加均显著增加。(4) As对叶绿素的影响由生长期的促进作用到枯黄期转为抑制作用; 不同物候期类胡萝卜素含量均与As浓度呈正相关; 叶绿素a与b含量之比与叶绿素a、b含量均呈极显著负相关。以上结果表明: 水烛通过限制As由根部向地上部的转移、细胞壁的固持和可溶性成分的区隔化以降低As的毒害; P的转移分布、抗氧化酶相互协作以及调整叶绿素配比和类胡萝卜素含量是水烛应对As胁迫的重要策略。
关键词：砷; 磷; 水烛; 亚细胞分布; 抗氧化酶; 叶绿素
Corresponding author: LIU Yungen; E-mail: firstname.lastname@example.org
In order to explore the characteristics of arsenic (As) accumulation and stress adaptation of emergent plants, we conducted hydroponic simulation experiments to study the distribution characteristics and physiological responses of As and phosphorus (P) in tissues and subcellular levels of a typical emergent plant (Typha angustifolia) at different phenological stages (growing period, flower and fruit perinotood, and withered period) under As stress (0, 0.5, 2, 5 and 10 mg·L−1). The results show that: (1) As was mainly accumulated in T. angustifolia roots, which were 12.56–21.29, 16.85–24.77 and 6.89–24.24 times of those in the leaves at growing, flower and fruit, and withered periods, respectively. With the growth of T. angustifolia, the sum of As distribution in the cell wall and soluble components of the leaves and roots at subcellular level were 69.96%–89.96% and 79.72%–93.96%, respectively, indicating that T. angustifolia stores As mainly at cell wall and soluble components. (2) P transfer coefficient of T. angustifolia was positively correlated with As concentration. At subcellular level, P was mainly distributed in the cell wall while transferred to nucleus and chloroplast under As stress. (3) As showed a low promoting and high inhibiting effect on antioxidant enzyme activity in T. angustifolia leaves, and catalase and peroxidase were complemented in different phenological stages. Malondialdehyde concentration was increased significantly with the growth of T. angustifolia and the increasing As concentration. (4) As inreased chlorophyll concentration in growing period while inhibited in withered period. Carotenoids concentration in different phenological stages was positively correlated with As concentration. Besides, the ratio of chlorophyll a content to chlorophyll b content was significantly negative correlated with chlorophyll a or chlorophyll b content. The above results show that T. angustifolia can reduce As toxicity by limiting As root-to-shoot transport, cell wall fixation and soluble component isolation. The P transport and distribution, antioxidant enzymes cooperation and chlorophyll ratio and carotenoid content adjustment were important strategies for T. angustifolia to cope with As stress.
Key words: arsenic; phosphorus; Typha angustifolia; subcellular distribution; antioxidant enzyme; chlorophyll
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