Genetic Diversity and Population Structure of Job’s Tears(Coix lacryma-jobi L.) Germplasm Based on ISSR Marker

Abstract Background: Job's tears（Coix lachryma-jobi L.）is a minor cereal and an important food item in some parts of Asia. It has also been used in the traditional Chinese medicine for relieving various ailments, therefore, it plays an important role in our lives. Lack of excellent new varieties hinders the development of coix as a sustainable crop, and it is urgent to provide new cultivars with excellent trait in Chinese Coix industry. Results: ISSR markers were used to assess the genetic diversity and population structure of 8 populations of Job’s tears in China. A genotyping analysis that utilized ten ISSR primer pairs resulted in the production of 116 bands, of which 98 were polymorphic. The Guizhou population (PPB = 81.90%, h = 0.3113, I = 0.4589) was the most genetically diverse, while the lowest was observed in the Hebei population (PPB = 46.55%, h = 0.1842, I = 0.2701). Genetic differentiation analyses including GST and AMOVA illustrated that genetic variation was most prevalent within populations while only minor variations were observed among populations. Genetic distance coefficients ranged from 0.0095 to 0.0948 for the 8 populations; the genetic relationship between the Guizhou and Chongqing populations was the closest, while the most distant genetic relationship occurred between the Hubei and Hunan populations. The results of an UPGMA cluster analysis that investigated genetic diversity among the populations were consistent with the genetic distance results. The results of a STRUCTURE analysis suggested that 94 Job’s tears accessions could be grouped into two subpopulations. Moreover, according to a cluster analysis based on the UPGMA for individuals of Job’s tears, accessions were divided into two major clusters. The results of the Bayesian cluster and UPGMA cluster analyses were largely consistent despite minor differences. There was no significant correlation between genetic distance and geographic distance (r = 0.055, p = 0.782). Conclusions: Our study was undertaken to systematically analyze genetic diversity and population structure in 94 Job’s tears accessions using ISSR markers. And this study provides us with valuable information pertaining to germplasm collection, genetic improvement, and systematic utilization of Job’s tears.