Identification of additional fire blight resistance candidate genes following MinION Oxford Nanopore sequencing and assembly of BAC clone spanning the Malus fusca resistance locus

Pyramiding different fire blight resistance genes and QTLs in future apple cultivars is the most eco-friendly way to combat this disease. Identification of strong fire blight resistance donors, and introgression of their resistance into apple breeding material are a continuing effort of breeding programs. Thus, enormous effort is been put into breeding research to understand host – pathogen interactions and mechanisms of resistance found in Malus. The crabapple Malus fusca (accession MAL0045) is highly resistant to fire blight, and although resistance is strain-dependent, resistance of MAL0045 is not overcome by any known strain of Erwinia amylovora to date. A strong fire blight resistance locus (FB_Mfu10) was fine mapped to an interval of 0.33 Centimorgan (cM) on linkage group (LG) 10 of MAL0045 using 1888 progenies. Subsequently, a single bacterial artificial chromosome (BAC) clone (46H22), which harbours FB_Mfu10-resistance alleles, was identified in a MAL0045 BAC library and sequenced using MiSeq illumina leading to the assembly of 45 contigs. Analyses of the sequence of 46H22 led to the identification of a receptor-like kinase candidate gene. Here, we report about resequencing 46H22 using MinION Oxford Nanopore and successfully assembled the sequences into a single contig, which allowed for identifying additional candidate genes.