古老铅锌矿区生态型东南景天对锌耐性及超积累特性的研究

 植物长期生长在重金属污染的生境中，逐渐进化成不同的生态型。通过调查中国东南部古老Pb/zn矿和非矿山生境中的植物种群，发现生长在古老Pb／Zn矿的东南景天(Sedum alfredii Hance)是一种新的Zn超积累植物。在自然和控制条件下，古老Pb／Zn矿生态型比非矿山生态型植株的茎粗、叶片大、植株高。在矿山土壤Zn有效含量为105.5～325.4mg·kg-1时，矿山生态型东南景天植株地上部Zn含量为4134～5000mg·kg-1；当营养液中Zn浓度为1223.6μmol时，其Zn含量高达2％。在相同Zn浓度下，矿山生态型地上部Zn含量比非矿山生态型高30倍左右。两种生态型体内Zn分布也不同，古老铅锌矿山生态型的不同器官中Zn含量以茎>叶片>根系，而非矿山生态型则以根系>茎>叶片。古老铅锌矿山生态型地上部积累的Zn占植株总积累量的90％以上，其中叶片和茎分别占41.66％±5.46％和54.75％±5.87％；非矿山生态型各器官中积累的Zn远远低于古老铅锌矿山生态型，各器官中积累的Zn以茎>根系>叶片。本研究表明，这两种生态型东南景天的发现，为今后探讨植物耐高Zn胁迫和超积累Zn的微进化过程提供了非常有价值的材料，也为Zn污染土壤的植物修复提供了一种很有潜力的候选材料。

Zinc Tolerance and Hyperaccumulation in a New Ecotype of Sedum alfredii Hance

Plants growing on heavy metal polluted soil environment can gradually evolve into differentiated ecotypes. In a survey of plant population in Zn/Pb mining and non-mining areas in southeast China,a new Zn-hyperaccumulating ecotype of Sedum alfredii Hance was found in an old Zn/Pb mining area. The old-mining ecotype showed a thicker stem, larger leaves and greater height and biomass under both natural and controlled growth conditions, relative to the non-mining ecotype. Shoot Zn concentration in the old-mining ecotype plants which grew on old mining soils with available Zn of 105.5-325.4 mg·kg-1,ranged 4134--5000 mg·kg-1,and reached as high as 2% under control condition. Shoot Zn concentration of the old-mining ecotype plants was over 30 times higher than that of the non-mining ecotype plants growing at the same external Zn concentration in the nutrient solution culture experiment (1223.6 μmol·L-1 in nutrient solution for 12 days). The distribution of Zinc in the plant differed between the two ecotypes, being stem > leaf > roots for the old-mining ecotype and root > stem > leaf for the non-mining ecotype. Shoot/root Zn ratio exceeded 10 in the old-mining ecotype, but were always 1 for the non-mining ecotype. The results showed that the old-mining ecotype of S. alfredii Hance is a Zn-hyperaccumulating ecotype, which has evolved from long-term exposure of plants to a high Zn soil environment. The finding of this ecotype is of importance for understanding micro-evolution mechanisms of Zn tolerance and hyperaccumulation of plants ,and for providing a new material for phytoremediation of Zn contaminated soils.