Validating Microsatellite Markers Linked to Remontancy in Octoploid Strawberry

The RosBREED project is focused on enabling marker-assisted breeding via discovery and development of DNA tests for the most valuable QTLs that are associated with traits that are important to breeders, producers, and consumers of rosaceous crops, including strawberry. The production season for strawberries is a very narrow window of a few weeks in the Pacific Northwest and Midwest, largely dominated by short-day strawberry cultivars. While the development of remontant (day-neutral) cultivars has greatly expanded the cropping season, their cultivation in the US has thus far been limited to California, mostly due to their sensitivity to spring and summer heat. Marker-assisted selection (MAS) will facilitate the development of new remontant cultivars. The objective of this study was to validate reported associations between remontancy and existing simple sequence repeat (SSR) markers identified from the ‘Capitola’ × CF1116 (C×C) and ‘Tribute’ × ‘Honeoye’ (T×H) populations. Remontancy phenotypic data was collected in MI and OR from 2011 to 2013 for 947 cultivated strawberry accessions composed of cultivars and selections representing diverse strawberry breeding germplasm and 42 pedigreed seedling populations. Plants were considered remontant if they flowered in the Spring and after July 16th. Remontancy was also determined quantitatively as the number of weeks of flowering after July 16th. For 2013, the number of flower trusses and the number of flowers per truss were counted, cut and counted again after four weeks. The number of runners was also recorded for each accession. Genotypic data was obtained in the 947 strawberry individuals for two SSRs flanking the FaPFRU gene reported to control remontancy in C×C and from six SSRs associated with six T×H remontancy QTLs. Many strongly remontant types were discovered that could provide novel sources of heat tolerance. The microsatellite allele dosage and configuration establishment (MADCE) method, where possible, is being used to quantitatively establish the full allelic configuration at the eight SSRs.  Association between marker alleles and haplotypes for these SSR markers and remontancy will be presented.