超富集植物遏蓝菜对重金属吸收、运输和累积的机制

遏蓝菜Thlaspi caerulescens可以在其地上部累积大量重金属如锌、镉等,是公认的超富集植物。由于该植物生物量小,不宜直接用于重金属污染的土壤植物修复,而被广泛作为一种模式植物来进行重金属富集机制研究。遏蓝菜对重金属离子的累积大致经过螯合剂解毒、地上部长距离运输以及在液泡中的储存等生理过程。已经发现的植物体内的金属螯合剂——有机酸、氨基酸、植物络合素(PCs)、金属硫蛋白(MT)和尼克烟酰胺NA等,区室化以及长距离运输相关的转运蛋白——ZIP(ZRT/IRTlike protein)、CDF(Cation diffusion facilitator)、Nramp(Natural resistance and macrophage protein)和HMA(Heavy metal ATPase)等家族,以上各种基因、多肽与蛋白等共同参与了植物对金属累积与耐受过程并发挥各自重要的作用。以下主要介绍了遏蓝菜重金属超富集相关的基因、多肽和蛋白,以及它们在重金属螯合作用和运输过程中的功能。

Heavy metal absorption, transportation and accumulation mechanisms in hyperaccumulator Thlaspi caerulescens

Thlaspi caerulescens, the famous model plant of heavy-metal hyperaccumulator, can uptake and accumulate large amount of heavy metals in its above-ground part of the plants. However, the very low biomass in Thlaspi caerulescens makes this plant unfit for direct application in phytoremediation. In recent years, there are many reports about the physiological and molecular characterization of Thlaspi caerulescens under heavy metals stresses, including absorption, transport and intracellular detoxification processes (e.g., chelation and compartmentation). Research teams have conducted many studies of chelators in plants, such as organ acid, amino acid, phytochelatins, metallothioneins and nicotianamine, and so on. Several transport protein families, such as Zinc Regulated Protein, Cation Diffusion Facilitator, Natural Resistance and Macrophage Protein and Heavy Metal ATPase, play important role in short/long distance transport in the plant. In this review, we summarize the current knowledge of the physiological and molecular mechanisms of heavy metals accumulation in Thlaspi caerulescens, with particular emphasis on the roles of transporters and chelatins in modulating plant heave-metal-stress responses.