Molecular Genetic And Epigenetic Diversity And Genetic Structure Of Wild Barley (Hordeum Brevisubulatum (Trin.) Link) Artificial Populations Endemic To Songnen Prairie, China

Genetic or epigenetic diversity and population genetic or epigenetic structure of 4 artificial populations of wild barley (Hordeum brevisubulatum (Trin.) Link), which comprised of a total of 96 individuals collected from the Songnen Prairie in northeastern China were analyzed by amplified fragment length polymorphism (AFLP), specific-sequence amplified polymorphism (SSAP) and methylation-sensitive amplified polymorphism (MSAP) markers. The efficiency of these three markers was also evaluated.We report here that by using a modified scoring criterion, MSAP marker can be used effectively to detect polymorphism in DNA methylation within and among populations of a perennial wild barley species, H.brevisubulatum. The resolving power of MSAP to detect DNA methylation polymorphism was found to be comparable to AFLP and SSAP, to detect genetic polymorphism in the same set of plants, suggesting that MSAP with a modified scoring criterion can be used efficiently in detecting DNA methylation polymorphism and assessing epigenetic population structure in plant populations.It was determined that a sample number of 12 was sufficient to represent the majority of genetic or epigenetic (in the form of DNA methylation) diversity for a given population of wild barley. Indices of (epi-)genetic diversity, (epi-)genetic distance, gene flow, genotype frequency, cluster analysis, PCA analysis and AMOVA analysis generated from MSAP, AFLP and SSAP markers had the same trend. On the basis of our results, there exists a high level of correlation in artificial populations between MSAP, SSAP and AFLP markers by Mantel test (r>0.8). This is incongruent with previous findings showing that there is virtually no correlation between DNA methylation polymorphism and classical genetic variations, and thus further corroborates the possibility that the high level of genetic polymorphism maybe as a result of epigenetic regulation.We also compared our results with the results of natural populations. And all results indicated the population diversity of the artificial populations was lower. However, unlike that detected by AFLP and SSAP, MSAP results showed that methylation polymorphism of the artificial populations was not significantly reduced but stand in parallel level. This suggested that DNA methylation pattern change in H. brevisubulatum populations is not only related to DNA sequence variation, but also being regulated by other controlling systems.