High-Throughput Digital Genotyping Tools for Panax ginseng Based on Diversity among 44 Complete Plastid Genomes

High-Throughput Digital Genotyping Tools for Panax ginseng Based on Diversity among 44 Complete Plastid Genomes

Cultivation of the medicinal herb Panax ginseng Meyer began by domesticating wild mountain ginsengs several hundred years ago in Korea. Elucidating the diversity of the maternally inherited plastid genome (plastome) in diverse ginseng collections including wild ginsengs would provide valuable information on ginseng breeding and cultivation history. We sequenced and compared the plastomes of 44 ginseng accessions collected from various Northeast Asian countries. The plastomes revealed 18 polymorphic sites, including 11 SNPs and 7 InDels, which portrayed less diversity than in the most closely related species, P. quinquefolius. We developed 10 kompetitive allele-specific PCR (KASP) markers and utilized them along with four previously developed InDel markers to characterize the genotypes of 203 ginseng accessions. Digital genotyping based on the developed KASP markers classified the accessions into 10 main and 2 branching haplotypes. Four InDel markers derived from different copy numbers of tandem repeats showed dynamic subgrouping within the haplotypes due to the occurrence of multi-alleles and reversible mutations. The digital haplotype genotyping (haplotyping) revealed that haplotype A, representing 60.1% of the accessions, might be the original plastome form without any SNP occurrence. Accumulation patterns of the variations suggest that nine main haplotypes (B-J) diverged independently by new SNP occurrences from the original plastome, and branching haplotypes may have derived from the first mutant lineage by additional SNP deposition. The digital haplotyping system based on plastome diversity deepens understanding of ginseng evolution and serves as a useful molecular breeding tool.