QTL analysis and marker development for fruit rot resistance in cranberry shows potential genetic association with epicuticular wax.

Abstract

Fruit rot is a fungal disease complex that continues to threaten cranberry yields in North American growing operations. Management of fruit rot is especially difficult due to the diversity of the infecting fungal species, and although infections take place early in the season, the pathogens usually remain latent in the ovary until the fruit ripen. Current control methods heavily rely on fungicide applications, a practice that may be limited in viability long term. Breeding for fruit rot resistance (FRR) is essential to sustainable production. It is likely that field resistance is multifaceted and involves a myriad of traits that fortify cranberry plants against the biotic and abiotic stresses contributing to fruit rot. In this study, we identified QTL for FRR in a segregating population. Interestingly, a QTL associated with resistance was found to overlap with one associated with fruit epicuticular wax (ECW). A SNP genotyping assay successfully identified accessions that exhibit the desired phenotypes (i.e., lower rot and higher epicuticular wax), thus making it a useful tool for marker assisted selection. Candidate genes that may contribute to FRR and ECW were also identified. This work will expedite breeding for improved cranberry fruit quality.