Effects Of Seed Artificial Aging On Genetic Integrity In Medicago Ruthenica Germplasm Resources

In this study, Medicago ruthenica were used to study effect of seed aging on the alteration of genetical integrity by physioloycial markers and two kinds of DNA molecular markers, SSR and ISSR. The purpose of this study was to provide scientific and theoretical basis for making a criteria for preserving Medicago ruthenica germplasm resources. Main results were as follows.1. Compared with the control population, seed aging had a significant impact on Conductance rate of leachate, MDA content, Soluble sugar content.2. Effect of seed aging on the change of genetical integrity for different germination ratio Medicago ruthenica germplasm was analyzed by ISSR markers. The result showed that Seed aging made the number of alleles, the number of polymorphic loci, percentage of polymorphic loci, the number of alleles per loci, index of genetical diversity and Shannon's information index decline significantly. The longer time of the artificial aging, the greater decline in the extent of genetical parameters. The genetical parameters of R showed very significant differences compared with the control population (P<0.01). The number of alleles per loci of W and X had significant differences compared with the control population.3. The results of SSR analysis showed seed aging made the number of alleles, the number of polymorphic loci, percentage of polymorphic loci, the number of alleles per loci, index of genetical diversity and Shannon's information index decline significantly. The longer time of the artificial aging, the greater decline of genetical parameters. The number of alleles per loci 20% germination population was lower than that of CK population, and the difference was significant (P<0.05).4. The results from SSR markers and ISSR markers were highly consistent. The genetical identity calculated by the two methods was highly positive significant. The number of polymorphic loci detected by ISSR markers was more than by SSR markers. Therefore, ISSR markers were more applicable to the analysis of change of genetical integrity of seed.