Identification of new resistance QTL regions in loquat cultivar Champagne against Pseudomonas syringae pv. eriobotryae group C
Loquat canker, caused by Pseudomonas syringae pv. eriobotryae, is a bacterial disease that infects loquat (Eriobotrya japonica) and has been reported in several countries. Three pathotypes, A, B, and C, have been reported in Japan. The loquat cultivar Champagne is resistant to the loquat canker group C and possesses a qualitative trait governed by a recessive homozygous pse-c gene located on Linkage Group 3 (LG3), and quantitative traits located at unidentified loci. In this study, we identified novel quantitative trait loci (QTL) regions for resistance to group C in this cultivar. A seedling population with Tanaka (Pse-c/Pse-c) crossed with Champagne (pse-c/pse-c) was tested. The genetic map of Champagne includes a total of 1,016 SNP markers mapped across 17 LGs, covering a total distance of 1,301 cM and an average marker density of 1.4 cM/locus. In addition to minor potential QTLs, the major QTL for resistance to loquat canker group C was detected in the upper region of LG14, with the QTL contributing 6.9% to the disease index. The results of this study open new possibilities for resistance breeding against this disease. Highlights.A total of 1,016 SNP markers were mapped on a linkage map consisting of 17 linkage groups with a total distance of 1,301 cM. QTL analysis revealed a novel resistance QTL region in Champagne against loquat canker group C in the upper part of the LG14. The identified QTLs in this study provide new possibilities for resistance breeding in loquat.