High-resolution genetic map and SNP chip for molecular breeding in a tetraploid medicinal plant.

Ginseng () renowned as the king of medicinal plants. Ginseng grows slowly under shade conditions, requiring at least 4 years to produce a limited number of seeds. Molecular breeding of ginseng faces challenges due to its the tetraploid genome and the absence of an efficient molecular marker system. To overcome these obstacles, we adopted genotyping-by-sequencing to delve into genetic mapping and survey genetic diversity. We constructed a comprehensive genetic map comprising 24 linkage groups, each corresponding to one of the 24 chromosomes in the ginseng genome, based on 1216 nonredundant SNPs obtained from an F mapping population. Additionally, 431 103 SNPs were identified from 119 diverse ginseng genotypes. From these, 192 informative subgenome-specific single copy SNPs were selected to develop a SNP chip. The SNP chip was used to genotype a large ginseng collection, encompassing registered cultivars, breeding lines, wild-simulated ginseng, and wild ginseng from various countries and regions. We evaluated the utility of the assay for molecular breeding with 919 ginseng genotypes. This breeder-friendly SNP chip promises versatility, enabling purity assessments of seeds and products, the authentication of species and cultivars, and the determination of homozygosity and homogeneity rates for breeding lines. Genotype data for 1200 ginseng genotypes are now stored in our database. This SNP chip lays the foundation for a molecular breeding in ginseng and will facilitate the breeding process in this medicinal crop.