Identification of new resistance QTL regions in loquat cultivar ‘Champagne’ againstPseudomonas syringaepv.eriobotryaegroup C

Abstract

AbstractLoquat canker, caused byPseudomonas syringaepv.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 homozygouspse-cgene 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.