ARS | Publication request: Using a Linkage Mapping Approach to Identify QTL for Day-Neutrality in the Octoploid Strawberry

Submitted to: Plant Breeding
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 22, 2006
Publication Date: February 1, 2008
Citation: Weebadde, C.K., Wang, D., Finn, C.E., Lewers, K.S., Luby, J.J., Bushakra, J., Sjulin, T.M., Hancock, J.F. 2008. Using a linkage mapping approach to identify QTL for day-neutrality in the octoploid strawberry. Plant Breeding. 127:94-101.

Interpretive Summary: Day-neutrality in strawberry is a trait in which plants flower and fruit constantly in temperate climates. This trait has been extremely valuable to the strawberry industry in California and other areas with similar environmental conditions as it has led to fantastic, 5-month-long production seasons. One of the challenges posed by day-neutrality is that it is difficult to find plants that not only exhibit this trait in environmental conditions that are different from those found in California but also have the ability to survive harsher climates. In this study, a June-bearing cultivar 'Honeoye' was crossed with a day-neutral cultivar ‘Tribute’ and the resulting seedling population was planted in Michigan, Minnesota, Maryland, Oregon and California. The goal was to identify quantitative trait loci (QTL) associated with the day-neutrality trait. This method provides valuable information that would allow for more efficient and accurate identification of day-neutral seedlings. Scientists would be able to develop new day-neutral cultivars without examining thousands of individuals over many years. This research also gave further insight into the inheritance of this trait. Our data supported the polygenic inheritance of day-neutrality as a number of QTL were identified that were either shared or location specific, and none of these QTL explained more than 36% of the phenotypic variation.

Technical Abstract: A linkage mapping approach was used to identify quantitative trait loci (QTL) associated with day-neutrality in the commercial strawberry, Fragaria ×ananassa (Duch ex Rozier). Amplified Fragment Length Polymorphic (AFLP) markers were used to build a genetic map with a population of 127 lines developed by crossing the day-neutral (DN) ‘Tribute’ with the short day (SD) ‘Honeoye’. The population was genotyped with AFLP markers and 387 single dose restriction fragments (SDRFs) were placed on a consensus map of 1310.7 cM with 42 linkage groups. Individuals from the mapping population were observed for their flowering habit throughout the growing season in Michigan (MI), Minnesota (MN), Maryland (MD), Oregon (OR) and California (CA). Eight QTL were found that were either location specific or shared among locations. None of these QTL explained more than 36 % of the phenotypic variation, indicating that the inheritance of day-neutrality is likely a polygenic trait.