School of Life Sciences and State Key Laboratory of Biocontrol, Sun Yat-sen University, Guangzhou, 510275, People's Republic of China.
BMC Evol Biol. 2012 Jun 13;12:84. doi: 10.1186/1471-2148-12-84.
Patterns of genetic divergence between populations of facultative metallophytes have been investigated extensively. However, most previous investigations have focused on a single plant species making it unclear if genetic divergence shows common patterns or, conversely, is species-specific. The herbs Rumex acetosa L. and Commelina communis L. are two pseudo-metallophytes thriving in both normal and cupriferous soils along the middle and lower reaches of the Yangtze River in China. Their non-metallicolous and metallicolous populations are often sympatric thus providing an ideal opportunity for comparative estimation of genetic structures and divergence under the selective pressure derived from copper toxicity.
In the present study, patterns of genetic divergence of R. acetosa and C. communis , including metal tolerance, genetic structure and genetic relationships between populations, were investigated and compared using hydroponic experiments, AFLP, ISSR and chloroplast genetic markers. Our results show a significant reduction in genetic diversity in metallicolous populations of C. communis but not in R. acetosa . Moreover, genetic differentiation is less in R. acetosa than in C. communis , the latter species also shows a clustering of its metallicolous populations.
We propose that the genetic divergences apparent in R. acetosa and C. communis , and the contrasting responses of the two species to copper contamination, might be attributed to the differences in their intrinsic physiological and ecological properties. No simple and generalised conclusions on genetic divergence in pseudo-metallophytes can thus be drawn.
人们已经广泛研究了兼性金属植物种群之间遗传分化的模式。然而，大多数先前的研究都集中在单一的植物物种上，因此不清楚遗传分化是否表现出共同的模式，或者相反，是否具有物种特异性。草本植物酸模（Rumex acetosa L.）和鸭跖草（Commelina communis L.）是两种拟金属植物，在中国长江中下游的正常和含铜土壤中都能茁壮生长。它们的非金属和金属种群往往是同域的，因此为比较估计在铜毒性的选择压力下的遗传结构和分化提供了理想的机会。
在本研究中，通过水培实验、AFLP、ISSR 和叶绿体遗传标记，研究并比较了酸模和鸭跖草的遗传分化模式，包括金属耐受性、遗传结构和种群间的遗传关系。我们的结果表明，鸭跖草的金属种群的遗传多样性显著降低，但酸模的遗传多样性没有降低。此外，酸模的遗传分化程度低于鸭跖草，后者的金属种群也表现出聚类。
我们提出，酸模和鸭跖草之间明显的遗传分化，以及这两个物种对铜污染的不同反应，可能归因于它们内在的生理和生态特性的差异。因此，不能对拟金属植物的遗传分化得出简单和普遍的结论。
