Genetic Biodiversity Of Moss Genus Haplocladium And Its Relationship With The Environmental Factors

Owing to simple structure without real roots and vascular tissue,large surface area, and the unique physiological and metabolic characteristics, bryophytes have high adsorptive ability of heavy metals and have been widely used as biological indicator for monitoring environmental pollution, especially heavy metal pollution in the world. Many previous studies have focused on environmental indicators, such as physiological and biochemical response, but there were only few research and reports on genetic diversity of the moss plants under heavy metal pollution. In recent years, Cao et al. selected the moss Haploadium as a good indicator to heavy metal pollution and their spacial and temporal changes during past 40 year in Shanghai, and achieved good results. In order to further explore of the relationships between genetic diversity and heavy metal pollution, we used Haploadium as experimental material to analyse genetic diversity of the moss plants under different habitat and heavy metal pollution condition by RAPD technique. The main research results are as follows:(1) By comparing three kinds of methods of plant genomic DNA extraction , the improved CTAB method was selected to be a good method for DNA extraction of moss Haplocladium. this method can extract high concentration and high purity DNA.(2) For heavy metal analysis, the plant samples were collected from nine different sites in Shanghai and the contents of Cd, Cr, Cu, Pb, Zn in the plats were determined by ICP.Compared the data in 2006 by An, present results showed that the Cu, Cr , Cd contents increased, with increasing rate Cr>Cu>Cd, while the Pb, Zn contents decreased, with decreasing rate Zn>Pb.(3) The genetic diversity of Haploadium from different habitats were analyzed by the method of RAPD. The result showed that plants of Haplocladium from different habitats have genetic differences, indicating that niche of Haplocladium have some effect on its genetic diversity. (4) Based on analysis of metal contents in the plants, using random amplified polymorphic DNA markers(RAPD), genetic diversity and genetic differentiations of the different populations were analyzed. The result showed the plants of Haplocladium have high genetic diversity. The degree of variation among the different populations is far greater than the degree of variation within populations. Correlation analysis between contents of heavy metals and Shannon information index of the deferent populations showed that increase of the Shannon index was positively correlated to increase of the Cr content.(5) The results demonstrated that Haplocladium is a good indication species for monitoring environmental heavy metal pollution. Under the heavy metal stress, Haplocladium populations showed some degree of differentiation and micro-evolution. The high level of genetic diversity of Haplocladium may be the basis for the Haplocladium adapt to heavy metal stress.