Genome-Wide Association Study Identifies Novel Loci Poten-tially Associated with Scab Susceptibility in Japanese Apricot (Prunus mume)

The Japanese apricot (Prunus mume) is a culturally and economically important fruit tree in East Asia. ‘Nanko’, the primary cultivar of Japanese apricot well known in Japan, usually suffers from scab, a disease caused by Venturia carpophila. Scabs result in the development of black spots on the fruit surface, which considerably reduce their commercial value. Despite being an economic concern, there have been few reports on phenotypic variation in scab resistance/susceptibility, the underlying genetic factors, and the development of DNA markers. Therefore, in this study, we performed a comprehensive trait analysis for naturally occurring fruit scab resistance and susceptibility over four years. We also conducted a genome-wide association study (GWAS), and significant peaks were detected in 2017 and 2018. Candidate genes associated with disease resistance were located around the nine single-nucleotide polymorphisms (SNPs) detected in 2017 and 2018. These SNPs were thought to be associated with scab susceptibility of ‘Nanko’ lineages. These findings shed light on phenotypic and genetic profiles of scab resistance in P. mume and will assist future breeding programs to improve scab resistance.