Abstract:

To explore the tolerance and detoxification mechanism of Typha Angustifolia L. to arsenic (As), hydroponic simulation experiments were conducted to analyze the accumulation, transport and subcellular distribution characteristics of As in Typha under As (0, 0.5, 2, 5 and 10 mg∙L^-1) treatments, In addition, the effects of As on plant growth and physiological and ecological characteristics were also investigated. Our results showed that: (1) The plant height, root length and biomass of Typha increased first and then decreased with the increase of As stress concentration, and reached the maximum when treated with 5 mg∙L^-1 As. (2) As was mainly accumulated in in Typha roots, accounting for 52.92%-93.47%. The enrichment coefficient and transfer coefficient were negatively correlated with As stress concentration. The distribution proportion of As in the soluble component (F4) and cell wall (F1) in roots and leaves was the highest, with the sum of the distribution ratios of F1 and F4 in leaves and roots is 64.48%-80.99% and 82.21%-92.96%, respectively. The accumulation is very unevenly distributed, with 21.21%-67.17% in the soluble components of the root, followed by the cell wall of the root (19.74%-39.26%). And (3) with the increase of As levels, the activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT), chlorophyll content and net photosynthetic rate of leaves were firstly increased and then decreased, while the ratio of chlorophyll a to chlorophyll b was on the contrary. The content of malondialdehyde (MDA) was 27.91-72.93 nmol∙g^-1 under As stress, which was 1.36-3.56 times higher than control group. Comprehensive analysis showed that Typha could reduce the toxicity of As to Typha via reducing the transfer of As to the aboveground part and cell wall fixation, inactivation of soluble components and regulation of antioxidant enzyme activity, and to maintain its normal physiological state.

Key words: typha, arsenic, subcellular distribution, chlorophyll, antioxidant enzymes

摘要：

为探究狭叶香蒲（Typha angustifolia L.）对砷（As）的耐受性和解毒机制,采用室内水培模拟实验,分析在不同As质量浓度（0、0.5、2、5、10 mg∙L^-1）污染下,As在狭叶香蒲体内的富集、转运和亚细胞分布特征及对植物生长、生理生态特征的影响。结果表明,（1）狭叶香蒲株高、根长和生物量均随As胁迫浓度的增加呈先升高后下降的趋势,在5 mg∙L^-1 As处理时达到最大值。（2）狭叶香蒲吸收的As主要富集在根部,占总富集量的52.92%—93.47%,富集系数和转移系数与As胁迫浓度呈负相关关系。As在根和叶的可溶性组分（F4）和细胞壁（F1）中的分布比例最高,在叶和根中F1、F4分配比例之和分别为64.48%—80.99%和82.21%—92.96%,但累积量分布极不均匀,主要分布在根的可溶性组分中,占植株总累积量的21.21%—67.17%,其次是根的细胞壁中,占19.74%—39.26%。（3）随着As胁迫浓度的增加,叶片超氧化物歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）活性以及叶绿素含量和净光合速率均呈先上升后下降的趋势,叶绿素a与叶绿素b的比值则相反,As胁迫下丙二醛（MDA）含量为27.91—72.93 nmol∙g^-1,为对照组的1.36—3.56倍。综合分析可知,狭叶香蒲通过减少As向地上部分的转移和细胞壁的固持、可溶性组分的钝化以及调节抗氧化酶活性等,降低As对狭叶香蒲的毒性,从而维持自身正常的生理状态。

关键词: 狭叶香蒲, 砷, 亚细胞分布, 叶绿素, 抗氧化酶