|CASTRO, PATRICIA - US Department Of Agriculture (USDA)|
Submitted to: Molecular Breeding
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/7/2016
Publication Date: 9/20/2016
Citation: Castro, P., Lewers, K.S. 2016. Identification of quantitative trait loci (QTL) for fruit quality traits and number of weeks of flowering in the cultivated strawberry. Molecular Breeding. 36(10):138-156.
Interpretive Summary: Breeding of strawberries, a fruit which has many valuable nutritional properties, is slow in part because seedlings derived from breeders’ crosses must be grown to maturity for evaluation of many traits, including fruit flavor and nutritional value or whether the plant will produce fruit all spring and summer or just a condensed crop in the spring. The breeding process would be greatly accelerated, and would be much more efficient, if a breeder could test test potential parent plants and know if their resulting family will contain plants with all the most desirable traits, or if a breeder could test a small seedling from these families and know with confidence what traits that seedling will have if grown to maturity. A DNA based method, called “marker assisted breeding” is available to accomplish this, but requires DNA “markers” that can be used to identify the parents or seedlings the breeder should “select.” This research reports the discovery of markers that can be used to help select seedlings that produce strawberry fruit all spring and summer and with great flavor and nutritional value. Strawberry breeders and geneticists worldwide will use these and new markers as they are discovered to be associated with other important traits.
Technical Abstract: Fruit quality traits and dayneutrality are two major foci of several strawberry breeding programs. The identification of quantitative trait loci (QTL) and molecular markers linked to these traits could improve breeding efficiency. In this work, an F1 population derived from the cross ‘Delmarvel’ × ‘Selva’ was used to develop a genetic linkage map for QTL analyses of fruit quality traits and total number of weeks of flowering. QTL for fruit quality traits were identified on Homoeologous Groups (HG) II, IV, V, VI and VII of the ‘Delmarvel’ and ‘Selva’ maps. The percentage of phenotypic variation explained by each QTL ranged from 4.8 to 10.7%. Some QTL were found in the same HG in previous studies (HG II, HG V and HG VI for total anthocyanins; HG V and HG VI for soluble solid content), supporting trait association in multiple genetic backgrounds. These QTL could be useful for marker-assisted breeding for fruit-quality traits in multiple breeding programs. One genomic region associated with the total number of weeks of flowering was identified on LG IV-S-1. The most significant marker was FxaACAO2I8C-145S, explaining 43.3 % of the phenotypic variation. The results of this study suggest that there is a major QTL for total number of weeks of flowering that is common to different populations. The day-neutrality trait, scored qualitatively, also was mapped on LG IV-S-1 linked to the markers FxaACAO2I8C-145S and ChFaM148-182DS/184DS. According to our results, the dayneutrality trait is controlled by a single dominant gene in this population.