Intraspecific Genetic Diversity Analyses of Yam (Dioscorea polystachya Turcz.) Based on DUS Traits and SSR Molecular...

Yam (Dioscorea polystachya Turcz.) is an asexually reproduced food and traditional Chinese medicinal crop with extensive genomic variability. However, the detailed characterization of genetic diversity among different yam germplasm samples is still insufficient. This study evaluated the genetic divergence and genetic structure of 113 D. polystachya accessions collected from 17 provinces in China based on 50 distinctness, uniformity, and stability (DUS) traits and 19 simple sequence repeat (SSR) markers. All the selected varieties were categorized into three groups based on morphological characteristics and further validated by principal component analysis. Furthermore, 14 core traits, including 6 leaf traits, 4 tuber traits, 3 bulbil traits, and 1 stem trait, were selected to increase field inspection efficiency. SSR fingerprinting, utilizing 19 highly polymorphic markers, successfully distinguished all 113 yam varieties, revealing relatively high levels of genetic variation. Interestingly, the optimal genetic structure defined three groups, whereas a finer-scale model consistently classified the varieties into five groups, corroborating the genotypic cluster analysis. Furthermore, this study preliminarily identified 10 groups of potential heterotypic synonyms and 13 groups of potential homonyms among the yam accessions. These results demonstrate that the 19 selected SSR markers, in conjunction with DUS traits, can effectively discriminate the 113 D. polystachya varieties. Our findings provide critical insights for the conservation of pure breeds and the utilization of Dioscorea germplasm resources.