2018 ASHS Annual Conference

Sweetpotato (Ipomoea batatas) is one of the most important root crops in the world, especially in Asian and African countries. It (called ‘satsuma-imo’) has been widely cultivated in Japan, and are utilized in many favorite dishes as well as industries. In Japan, sweetpotato breeding is conducted vigorously to improve the yield, components of storage root and tolerance to pest and disease resistances. However, the genetic information in sweet potato germplasms has been limited due to its hexaploidy (2n=6x=90) and self-incompatibility characteristics, which complicated genetic analysis. Whole genome sequence of the diploid relatives of sweetpotato, I. trifida, has been revealed recently and enabled to develop genome wide single nucleotide polymorphisms (SNPs) in sweetpotato. In this study, genetic variation among 94 diverse sweet potato accessions conserved in the National Agriculture and Food Research Organization, Japan, was assessed using genome wide SNPs to elucidate genetic background in sweetpotato germplasm and thereby to accelerate the use of suitable germplasm for breeding new cultivars. The 94 accessions consist of 13 Japanese landraces, 67 exotic landraces and cultivars (Central and South America, USA, East and Southeast Asia, Oceania and Uganda) introduced into Japan, 9 recent cultivars released in Japan and 5 wild-relatives (I. trifida). Morphological traits of each accession were evaluated under field condition. A total of 23,535 SNPs was detected among 94 accessions using double-digest restriction site-associated DNA sequence (ddRAD-seq) method. Analysis of genetic population structure indicated that sweetpotato accessions were divided into 5 clusters (K=5). Phylogenetic tree based on neighbor-joining method with 23,535 SNPs revealed the relationship among the accessions, which reflected the geographical origin of the accessions and known kinship of the released cultivars.