【摘要】 砷超富集植物——蜈蚣草体内可以富集高浓度的砷且不表现出受害症状,暗示蜈蚣草细胞具有较强的砷解毒机制.为探讨抗氧化系统在蜈蚣草砷解毒机制中的作用,测定了0、0.5、1和2mmol/L的砷酸盐[As(Ⅴ)]、亚砷酸盐[As(Ⅲ)]和二甲基胂酸盐(DMA)处理下蜈蚣草愈伤组织的丙二醛(Malonyldiadehyde,MDA)含量、非酶类抗氧化物质含量和酶类抗氧化物质的活性.结果表明,0.5mmol/L As(Ⅴ)和DMA就可以诱导氧化胁迫的产生,浓度越高胁迫程度也越严重.而1mmol/L的As(III)仍未使蜈蚣草愈伤组织产生氧化胁迫.在As(Ⅲ)处理下,酸溶性巯基含量增加,叶绿素和类胡萝卜素含量不变,过氧化氢酶(Catalase,CAT)和过氧化物酶(Peroxidase,POD)活性增加.在As(Ⅴ)处理下,酸溶性巯基含量减少,叶绿素和类胡萝卜素含量略有上升;CAT和POD活性先增加后减少.在DMA处理下,酸溶性巯基含量减少,叶绿素含量降低而类胡萝卜素含量增加,CAT和POD活性先增加后减少.与As(Ⅴ)和DMA相比,As(Ⅲ)处理下高酸溶性巯基含量、高氧化酶活性和低MDA含量暗示As(Ⅲ)对蜈蚣草的毒性可能比As(Ⅴ)和DMA要小.这些结果表明,酸溶性巯基和酶类抗氧化物质(CAT和POD)在蜈蚣草细胞砷解毒机制中发挥着重要作用.图4参22更多还原

【Abstract】 Pteris vittata L.,one of arsenic(As) hyperaccumulators,can accumulate high concentration arsenic and show no signs of toxicity,indicating the existence of effective plant-internal detoxification mechanisms.In order to elucidate the role of anti-oxidative system in P.vittata arsenic detoxification mechanisms,the concentrations of malonyldiadehyde(MDA),acidsoluble thiols,chlorophyll and carotenoid,and the activities of catalase(CAT) and peroxidase(POD) in P.vittata callus under 0,0.5,1,and 2 mmol/L arsenate,arsenite and dimethylarsenic acid(DMA) stress were determined.A significant increase in MDA concentration was observed under arsenate and DMA exposure,while no significant induction of MDA in 1 mmol/L arsenite treated callus.Under arsenite exposure,the acid-soluble thiols concentrations were significantly elevated,the activities of CAT and POD were enhanced in response to the increasing of arsenic concentration,chlorophyll,and carotenoid concentrations.While under arsenate and DMA exposure,the acid-soluble thiols concentrations were significantly reduced,the activities of CAT and POD increased with arsenic concentration rising to 0.5 mmol/L,and then decreased.Higher activities of anti-oxidative enzymes and lower MDA concentration suggest that the toxicity of arsenite may lower than that of arsenate and DMA.These results indicate both acid-soluble thiols and enzymatic antioxidants(CAT and POD) play important roles in P.vittata arsenic detoxification system.Fig 4,Ref 22更多还原