摘要:
以133Cs作为污染源,溶液培养印度芥菜和菊苣幼苗,研究植物螯合肽(phytochelatins,PCs)、金属硫蛋白(metallothionein,MT)等含巯基肽类物质与Cs+胁迫毒理的内在联系。采用改良水培法培养印度芥菜和菊苣长至两片真叶,置于含铯[ρ(Cs+)0~200 mg·L-1]的营养液中培养一段时间后取样,测定幼苗地上部和根系生物量,采用火焰原子吸收分光光度法测定Cs+富集量,5,5’-二六硝基苯甲酸(DTNB)比色法测定PCs和MT含量。结果显示:随着Cs+浓度[ρ(Cs+)25~200 mg·L-1]增加,印度芥菜和菊苣地上部和根系生物量显著降低(P<0.05),印度芥菜的生物量降低幅度小于菊苣;Cs+的富集量均显著增加,印度芥菜对Cs+富集量大于菊苣,印度芥菜地上部、菊苣根系分别是Cs+的主要蓄积部位;非蛋白巯基肽类(non-protein thiol,NPT)、植物螯合肽(PCs)、谷胱甘肽(glutathione,GSH)和金属硫蛋白(MT)含量变化均呈现先升后降的趋势,均表现为根系>地上部,印度芥菜>菊苣。当ρ(Cs+)100 mg·L-1时NPT、PCs、GSH和MT达最大值。结果表明,菊苣对Cs+处理敏感,印度芥菜具有较强的吸收和转运Cs+的能力,Cs+处理诱导合成PCs、GSH和MT含量显著增加,这是印度芥菜对Cs+耐性较强的主要原因。
Abstract:
This study seeks to investigate the relationship between Cs toxicity and the content of phytochelatins (PCs) and metallothionein (MT) in Brassica juncea and Cichorium intybu. We subjected seedlings at the two-leaf stage to different doses of Cs+[ρ(Cs+) 0-200 mg·L-1] for two to nine days. Next, we analyzed the dry biomass, and the content of Cs+, PCs and MT in the over-ground and the root. The results show that the dry biomass of overground and root decreased in both plants when Cs+ concentration increased (P<0.05). However, the decrease of dry biomass induced by Cs+ followed the order as Cichorium intybu > Brassica juncea. With the increase in Cs+ concentration, the accumulation content of Cs in both plants increased significantly (P<0.05). The capacity for accumulation for Cs+ showed that:Brassica juncea > Cichorium intybu. The root of Cichorium intybu is the main accumulation organ for Cs+, but the over-ground is the main accumulation organ in Brassica juncea. With the increase of Cs+, the content of non-protein thiol (NPT), PCs, gultathione (GSH), and MT first increasd and then decreasd, and the content of both plants maximized when the concentration of Cs+ reached 100 mg·L-1. Further analysis shows that the roots had a higher content of NPT, GSH and MT than over-ground in both plants, and Brassica juncea had a higher content than Cichorium intybu. Our findings show that Cs+ tolerance in Brassica juncea was higher than that in Cichorium intybu. Cs+ can induce the synthesis of PCs, GSH, and MT in Brassica juncea when the plants have accumulated excessive Cs+.
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