2016 Volume 15 Issue 3 Pages 233-240
Loquat canker is one of the most serious diseases of commercial varieties of loquat (Eriobotrya japonica). The pathogens are classified into three groups (A, B, and C) based on the production of a brown pigmentation in culture medium and pathogenicity to mesophyll. For marker-assisted selection (MAS) of Group A-resistant seedlings, we developed new simple sequence repeat (SSR) markers and fine-mapped the loquat canker-resistant gene Pse-a of bronze loquat (E. deflexa). The high-density linkage map included the Pse-a gene and 9 SSR markers, spanning 9.0 cM, with an average density of 0.9 cM per marker. The genotypes of these SSR markers were compared with the resistant phenotype of loquats from Japan (43 cultivars), other countries (13 cultivars), and unknown (1 cultivar). We found that two resistance-specific markers, SSR0254 and SSR0858, corresponded well with the resistant phenotype. The recombination values in two seedling populations between the marker and Pse-a were 2.3 and 12.6% for SSR0254, and 4.6 and 10.3% for SSR0858, respectively. Seedlings predicted to be resistant on the basis of SSR0254 or SSR0858 were resistant in an inoculation test with a probability of more than about 90% in every cross combination. We conclude that these markers may be useful in loquat breeding programs for MAS of individuals resistant to Group A.
