Assessment of genetic integrity of Siberian wild rye (Elymus sibiricus L.) germplasm conserved ex situ and under accelerated aging using microsatellite markers

Abstract

Genetic changes in Siberian wild rye (Elymus sibiricus L.) germplasm conserved ex situ and with accelerated aging were studied using microsatellite markers. Five accessions, divided and deposited in the National Medium-term Genebank of Forage Germplasm of China (NMGFC) and the National Genebank of China (NGC) since 1998, were sampled. Four recently-regenerated accessions were selected to assess genetic changes under accelerated aging conditions using a thermostat-controlled cabinet at 45 °C for 7–13 days to obtain seeds with germination rates (Gr) of approximately 80%, 50%, and < 30%. Twenty-four simple sequence repeat (SSR) markers were used to screen 70 seeds of each sample and 137 SSR alleles in a naturally-aged germplasm set and 113 SSR alleles in an accelerated aging germplasm set were scored. Loss of alleles was observed with respect to the primer pair and sample in the NMGFC compared to that in the NGC, but no significant differences were found for each accession in seeds stored in NMGFC compared to that in seeds stored in NGC. Among-sample differences were the largest contributors to total SSR variation, at 70.6% and 76.2% for naturally-aged and accelerated-aging samples, respectively. Gr did not separate samples in either germplasm set based on genetic association analysis. Prominent changes in genetic diversity were found both in naturally-aged and accelerated-aging samples, with significant decreases in Shannon’s information index and Nei’s genetic diversity for cases with Gr ≤ 30% for both germplasm sets. These results should be valuable to improve the safe conservation of forage, especially for Elymus (family Gramineae).