2018 ASHS Annual Conference

Variable temperature and humidity in central Florida provide challenges for maintaining fruit quality and disease-free conditions in strawberry (Fragaria ×ananassa) production. The present study investigates the genetic architecture of resistance to charcoal rot (CR) caused by Macrophomina phaseolina, anthracnose fruit rot (AFR) caused by Colletotrichum acutatum, and fruit volatile compounds in the University of Florida (UF) strawberry breeding program. Clonal replicates of more than 1100 seedlings from 73 full-sib families were control-inoculated with M. phaseolina during two consecutive growing seasons in Florida, and clonal replicates of more than 700 seedlings from 38 full-sib families were controlled inoculated with three isolates of C. acutatum. In addition, five crosses were evaluated for fruit volatile compounds. Phenotyping of disease resistance was conducted weekly, rating plant collapse for CR and fruit incidence for AFR. Population-wide volatile metabolomics were generated via SPME-GC/MC with statistical alignment via Metaling software for flavor compounds. Genotyping was performed using Axiom® IStraw90 and IStraw35 SNP arrays. A pedigree-based analysis was performed for genome-wide QTL detection using FlexQTL™. Two major-effect loci, FaRMp1 and FaRMp2, on linkage groups (LG) 2AII and LG 4B, together explained 58% of the phenotypic variation in mortality due to CR; a single large-effect locus, FaRCa1, for AFR on LG 6B explained 51% of phenotypic variation for AFR incidence; and a major QTL for Linalool along with several other moderate-effect QTLs for other flavor compounds were detected. Validation of these loci may facilitate development of marker-assisted breeding tools and techniques for these traits.