Genome‐wide association mapping identifies novel loci underlying fire blight resistance in apple

Fire blight, caused by epiphytotic gram-negative bacteria Erwinia amylovora, is the most destructive bacterial disease of apple (Malus spp.). Genetic mechanisms fire blight resistance have mainly been studied using traditional biparental quantitative trait loci (QTL) mapping approaches. Here, we use large-scale historic shoot and blossom data collected over multiple years genotyping-by-sequencing (GBS) markers to identify significant marker–trait associations in a diverse set 566 [Malus domestica (Suckow) Borkh.] accessions. There was large variation susceptibility these We identified 23 38 QTL significantly (p < .001) associated with resistance, respectively. The are distributed across all 17 chromosomes apple. Four 19 this study colocalized previously or scab. Using transcriptomics two cultivars contrasting responses, also candidate genes for that differentially expressed between resistant susceptible located within intervals resistance. However, further experiments needed confirm validate develop diagnostic before marker-assisted breeding decreased susceptibility.