Breeding apple cultivars with resistance offers a potential solution to fire blight, a damaging bacterial disease caused by Erwinia amylovora. Most resistance alleles at quantitative trait loci (QTLs) were previously characterized in diverse Malus germplasm with poor fruit quality, which reduces breeding utility. This study utilized a pedigree-based QTL analysis approach to elucidate the genetic basis of resistance/susceptibility to fire blight from multiple genetic sources in germplasm relevant to U.S. apple breeding programs. Twenty-seven important breeding parents (IBPs) were represented by 314 offspring from 32 full-sib families, with ‘Honeycrisp’ being the most highly represented IBP. Analyzing resistance/susceptibility data from a two-year replicated field inoculation study and previously curated genome-wide single nucleotide polymorphism data, QTLs were consistently mapped on chromosomes (Chrs.) 6, 7, and 15. These QTLs together explained ~28% of phenotypic variation. The Chr. 6 and Chr. 15 QTLs colocalized with previously reported QTLs, while the Chr. 7 QTL is possibly novel. ‘Honeycrisp’ inherited a rare reduced-susceptibility allele at the Chr. 6 QTL from its grandparent ‘Frostbite’. The highly resistant IBP ‘Enterprise’ had at least one putative reduced-susceptibility allele at all three QTLs. In general, lower susceptibility was observed for individuals with higher numbers of reduced-susceptibility alleles across QTLs. This study highlighted QTL mapping and allele characterization of resistance/susceptibility to fire blight in complex pedigree-connected apple breeding germplasm. Knowledge gained will enable more informed parental selection and development of trait-predictive DNA tests for pyramiding favorable alleles and selection of superior apple cultivars with resistance to fire blight.

Diabetic ketoacidosis (DKA) is not a rare presentation to hospital, despite being an entirely preventable condition. A concerning number of people also develop DKA while already in hospital. Management of DKA has changed in the last decade, and national guidelines introduced, to help standardise care, spread best practice, and reduce mortality and morbidity.

Selecting for crispness instrumentally in fruit from apple (Malus ×domestica) breeding programs is notoriously difficult. Most breeders rely on sensory assessment for this important characteristic. Following the 2009 harvest, we used a computerized penetrometer to assess firmness and texture of apple selections from the Washington State University's apple breeding program and 16 standard reference varieties. Data were compared with sensory data from the apple breeding team. In addition to the expected high correlations between the various firmness measures of the computerized penetrometer and the sensory firmness values, our data also show a significant correlation between the computerized penetrometer crispness value and the sensory crispness value, thus demonstrating the benefit from using this equipment rather than the industry standard Magness–Taylor penetrometer.

Systematic studies of the relative importance of apple traits for U.S. apple producers to inform U.S. apple breeding programs have been lacking. To fill this gap, a series of audience surveys with instant feedback at five apple producer meetings across the United States was conducted. The traits included in this study were fruit crispness, juiciness, firmness, flavor, soluble solids concentration, sugar–acid balance, shelf life at retail, freedom from storage disorders, host plant disease resistance, and other fruit and tree traits provided by the producer. Producers rated fruit flavor and crispness as the most important traits for a successful apple cultivar. The relative importance assigned to traits was associated with growing location and producers’ years of experience in the decision-making process of managing apple orchards. This study contributes directly to a larger effort that provides breeding programs with systematic knowledge of trait preferences of supply chain members, including producers, and should result in a more targeted approach to developing and commercializing new apple cultivars.