Genetic differences and variation in polysaccharide antioxidant activity found in germplasm resources for Job’s tears (Coix lacryma-jobi L.)

Job’s tears (Coix lacryma-jobi L.) is an ancient plant with high nutritional and medicinal value. In this study, using 11 Chinese germplasm resources for Job’s tears, we examined genetic differences among the germplasms and differences in the in vitro antioxidant activities of coixan, and sought to identify inter-relationships between these two variables. We found that the intraspecific conservation of DNA sequences was high, with ITS regions and cpDNA trnL-F and trnH-psbA non-coding sequences showing no sequence variation, whereas the GBSSI gene showed a certain degree of variation among the different germplasms. EST-SSR analysis also revealed a relatively low level of genetic diversity among the germplasms. Coixan was shown to be an efficient antioxidant, and among the germplasms examined, the LNYX, FJPC, and AHBZ had the highest antioxidant activities. However, none of the four in vitro antioxidant activity indices we assessed were significantly correlated with the geographical origin of the germplasm (latitude and longitude); however, one of them was significantly associated with genetic diversity. Although the factors affecting the antioxidant activity of coixan are complex, the role of heredity should not be ignored. Our findings have implications for the scientific evaluation, identification, and sustainable utilization of the germplasm resources for Job’s tears.