Preliminary QTL mapping to resolve putative homozygous fire blight resistance locus in Malus fusca MAL0045

Emeriewen, Ofere, Francis; Flachowsky, Henryk; Peil, Andreas

doi:10.17660/ActaHortic.2024.1412.13

refereed

published

Preliminary QTL mapping to resolve putative homozygous fire blight resistance locus in Malus fusca MAL0045

Emeriewen, Ofere Francis ; Flachowsky, Henryk ; Peil, Andreas

The most destructive bacterial disease of apples (Malus domestica Borkh.) and its relatives is fire blight, caused by the bacterium Erwinia amylovora. Strong resistance to fire blight has been found in some wild apple accessions including Malus ×robusta 5 (Mr5) and Malus fusca accession MAL0045. Only one major QTL that explained 66% of the phenotypic variance in an F₁ population derived from crossing MAL0045 and the apple cultivar ‘Idared’ was mapped on linkage group 10 (LG10) of MAL0045 (Mfu10). Since Mfu10 explains only 66% of phenotypic variation, we assumed the existence of other resistance factors in the genome of MAL0045, which were not segregating in the F₁ individuals. We established an F₂ population of MAL0045 by crossing F₁ progenies, and used their genotypic and phenotypic data to determine whether marker-trait associations could be observed in linkage groups other than LG10. A significant association was found on LG4, which could contribute to fire blight resistance of MAL0045.