|CASTRO, P. - Collaborator|
|WEEBADDE, C.K. - Michigan State University|
|WANG, D. - Michigan State University|
|HANCOCK, J.F. - Michigan State University|
|STEWART, P. - Driscoll'S|
|LUBY, J.J. - University Of Minnesota|
Submitted to: Molecular Breeding
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/27/2014
Publication Date: 2/13/2015
Publication URL: http://handle.nal.usda.gov/10113/61526
Citation: Castro, P., Lewers, K.S., Weebadde, C., Wang, D., Hancock, J., Stewart, P., Bushakra, J., Finn, C.E., Luby, J. 2015. Genetic mapping of day-neutrality in cultivated strawberry. Molecular Breeding. 35(2):79-94.
Interpretive Summary: Breeding of strawberries is slow in part because seedlings derived from breeders’ crosses must be grown to maturity for evaluation of many traits, including whether the plant will produce fruit all spring and summer or just in the spring. The breeding process would be greatly accelerated, and would be much more efficient, if a breeder could test a small seedling and know with confidence what traits that seedling will have if grown to maturity. A DNA based method, called “marker assisted selection” that utilizes DNA markers to identify seedlings with desired traits was utilized. This research reports the discovery of markers associated with flowering in strawberry. These markers can be used to select seedlings that will grow to produce strawberry fruit all spring and summer, as opposed to just in the spring. Strawberry breeders and geneticists worldwide will use these new markers to develop improved strawberry varieties.
Technical Abstract: Day-neutrality is a highly desirable trait in strawberry (Fragaria L.) breeding programs worldwide due to its importance in extending the harvest season in commercial production. Day-neutral genotypes are photoperiod insensitive and will initiate flowers under any photoperiod conditions as long as temperatures are moderate (below 30/26 °C day/night). In the current study, the inheritance of day-neutrality was investigated using an F1 population derived from the cross ‘Tribute’ × ‘Honeoye’. The day-neutral trait was scored qualitatively [day-neutral (DN) or short-day (SD)], and quantitatively (number of weeks of flowering). When qualitatively scored in five locations, the day-neutral trait fit a 1:1 segregation ratio in the hot summers of Maryland (MD), Minnesota (MN) and Michigan (MI), and segregation was skewed towards additional DN progeny in the cooler summers of California (CA) and Oregon (OR). Regardless of evaluation location, the trait was mapped on Linkage Group IV-T-1 of the ‘Tribute’ map near the markers ChFaM148-184T and ChFaM011-163T. Quantitative-trait loci (QTL) for number of weeks of flowering in MD and CA also were identified on Linkage Group IV-T-1 of the ‘Tribute’ map. These QTL were significantly associated with the qualitatively scored trait and its closely linked molecular markers. The markers ChFaM148-184T and CX661047a-118T had the highest LOD scores and explained 63.8% and 50.1% of the total phenotypic variation for the number of weeks of flowering for MD and CA, respectively. Consequently, it was hypothesized that a single major gene or tightly linked cluster of genes in coupling control day neutrality in this population. The results found in the current study suggest that day neutrality can be qualitatively scored at least in the locations where the temperatures do not allow short-day plants to behave as day-neutral.