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 DN trait fit a 1:1 segregation ratio in the hot summers of Maryland (MD), Minnesota (MN) and Michigan (MI). Segregation was skewed toward 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 and for stolon or ‘runner’ production in MN, MI and OR 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 marker ChFaM148-184T explained 63.8 % of the total phenotypic variation for the number of weeks of flowering for MD and 32.4 % of the total phenotypic variation for runner production in MN. 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 SD plants to behave as DN.
Bibliographical noteFunding Information:
This project was partially funded by the USDA Cooperative State Research, Education and Extension Service—National Research Initiative—Plant Genome Program (Award # 2005-35300-15468), USDA-ARS Projects 1245-21220-254-00 and 5358-21220-002-00, Driscoll Strawberry Associates, Inc., Michigan State University and the University of Minnesota. Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture or any of the other agencies involved in this research.
© 2015, Springer Science+Business Media Dordrecht (outside the USA).
- Linkage map
- Photoperiod insensitivity
- QTL map