Evaluation of genetic integrity of pearl millet seeds during aging by genomic-SSR markers.

Seed is an important way to store germplasm resources but its genetic integrity will decrease during long-term preservation. So, it's essential to update seeds according to the aging level of different species. Pearl millet [Cenchrus americanus (L.) Morrone syn., Pennisetum glaucum (L.) R. Br.] is a crucial forage grass, biofuel plant and important crops in the world bringing huge economic and ecological benefits. However, there is no report about the impact of aging on genetic integrity of its seeds. In this study, four genetic diversity indexes (the percentage of polymorphic bands, PPB; the effective number of alleles, Ne; the Nei's gene diversity index, H; the Shannon's information index, I) and 20 pairs of genomic-SSR primers were used to certify the optimal sample volume of pearl millet for molecular study and found that the best sample volume was 60. After the artificial aging test, the germination rate and four genetic diversity parameters (the number of alleles, Na; Ne; H; I) were used to evaluate the change of genetic integrity at different aging levels. The results showed that the germination rate and these four genetic diversity parameters declined with the increase of aging levels. Furthermore, when the germination rate of pearl millet seeds went down to 68.23%, a significant difference in genetic integrity was observed with unaged seeds. In conclusion, the optimal sample size of pearl millet was 60 and the critical point of germination rate to renew germplasm resources was 68.23% and these finds might contribute to the scientific study and the safe conservation of pearl millet.