两种生态型东南景天锌吸收与分布特性的研究

采用水培试验,研究了非超积累和超积累两种生态型东南景天吸收、分配和转运锌(Zn)的特点.结果表明:两种生态型植物不仅在生长速度上对Zn浓度的反应差异显著,而且在Zn吸收与分配特性上也有明显差异.非超积累生态型的最适生长浓度为0.001 mmol/L, 在此Zn水平下,生物量随处理时间基本呈直线性增长;而超积累生态型的最适生长浓度为1.0 mmol/L,生物量在处理前16 d呈直线性增长,以后趋缓.非超积累生态型地上部的最大Zn含量远低于超积累生态型;而根部的最大Zn含量,非超积累生态型显著大于超积累生态型.Zn在非超积累生态型细胞壁和可溶部分中的含量差异不显著,在细胞器与膜部分的含量相对较低,而Zn在超积累生态型细胞壁中含量最高,其次是细胞的可溶部分.综合分析认为:超积累生态型东南景天比非超积累生态型具有更强的Zn积累和耐受能力,前者可能是后者在高Zn环境中长期进化的结果.

Study on zinc uptake and distribution in zinc hyperaccumulating and non-hyperaccumulating ecotypes of Sedum alfredii Hance

Characteristics of plant growth and uptake and distribution of zinc (Zn) in Zn hyperaccumulating and non-hyperaccumulating ecotypes of Sedum alfredii Hance in response to Zn concentration were compared by solution culture experiments and significant differences were found between the two ecotypes. The optimum Zn concentration for growth of Zn hyperaccumulating ecotype is 1.0 mmol/L Zn, at which dry weight of the plant increased linearly with time in initial 16 days; thereafter, the plant growth rate decreased gradually. In contrast, the optimum Zn concentration for growth of non-hyperaccumulating ecotype is 0.001 mmol/L. At this external Zn level growth of the plant dry weight increased linearly in whole period. The maximum Zn concentration in the shoots of Zn hyperaccumulator was much greater than in that of non-hyperaccumulator, but an inverse relationship between the two ecotypes was found when their Zn concentrations in roots were compared. In Zn hyperaccumulating plant, Zn concentrations in different plant cell fractions were in the following order: cell wall>cytosol>cell organelle/membrane system, while in non-hyperaccumulating plant, cell wall and cytosol contained Zn at similar level, which was higher than that in cell organelle/membrane system. It is suggested that the Zn hyperaccumulating ecotype was formed as a result of long time adaptation and evolution in Zn-enriched environment.