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. ### Competing Interest Statement The authors have declared no competing interest.