蜈蚣草的组织培养快繁及拮抗重金属Cr6+胁迫的生理机制探究

An efficient regeneration system and physiological responses to chromium stress of Pteris vittata

为探究重金属超富集植物蜈蚣草治理、修复土壤重金属铬(chromium,Cr)污染的能力,在建立高效蜈蚣草组培再生体系基础上,通过在培养基中添加不同浓度重铬酸钾(K_(2)CrO_(4),Cr^(6+)),检测被处理羽叶中色素含量和超氧化物歧化酶(superoxide dismutase,SOD)活性等生理生化指标.结果表明:以成熟孢子为外植体,经过适宜的培养基和条件培养,最短可在3~4个月内获得大量的蜈蚣草组培苗.随着培养基中施加的Cr^(6+)浓度提高及胁迫时间的延长,羽叶中叶绿素、类胡萝卜素及丙二醛(malondialdehyde,MDA)质量浓度呈现“上升→下降→上升”的波动趋势;低浓度Cr^(6+)胁迫处理后,蜈蚣草羽叶中SOD和过氧化物酶(peroxidase,POD)活性则呈现先下降后上升的趋势;当Cr^(6+)胁迫浓度超过1.0 mmol/L时,蜈蚣草羽叶在6 d内由绿色逐渐转变为褐色,并发生萎蔫,叶绿素等生理指标也较对照差异显著,表明蜈蚣草对Cr^(6+)胁迫具有较强的耐受性,但高浓度Cr^(6+)胁迫可能抑制了蜈蚣草体内的抗氧化系统,从而呈现明显的毒害症状.研究为应用蜈蚣草治理、修复土壤中重金属Cr^(6+)污染等提供一定的理论依据.

In order to evaluate the tolerant and remediate abilities of hyperaccumulator Pteris vittata L.to heavy metal chromium(K_(2)CrO_(4),Cr^(6+)),mature spores was used as explants to establish an efficient regeneration system,the regenerated seedlings were used to detect physiological indexes after exposed to different con-centrations of Cr^(6+),including the contents of chlorophyll a and b,carotenoid and malondialdehyde(MDA),and the activities of superoxide dismutase(SOD)and peroxidase(POD).The results showed that numbers of seedlings were regenerated in 3~4 months with suitable mediums and culture condition.After exposed to five concentrations of Cr^(6+)(0~3.0 mmol/L)for 2~6 d,the levels of chlorophyll a and b,carotenoid and MDA in regenerated Pteris vittata fronds exhibited a′increase➝decrease➝increase′tendency,while the activities of SOD and POD showed a tendency of′decrease-increase′with lower Cr^(6+)concentrations.Moreover,the fronds became brown and dehydrated,and the physiological indexes significantly changed after treated with more than 1.0 mmol/L of Cr^(6+),indicated that Pteris vittata was a tolerant fern species response to Cr^(6+).However,high level of Cr^(6+)was accumulated in fronds might inhibited or destroyed antioxidant activities,and showed an obviously toxic phenotype.These results could provide new clues for phytoremediation of chromium-contaminated soils and fields.