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 Polymorphism (AFLP) markers were used to build a genetic map with a population of 127 lines developed by crossing the dayneutral (DN) ÔTributeÕ with the short-day (SD) ÔHoneoyeÕ. The population was genotyped with AFLP markers and 429 single dose restriction fragments (SDRF) were placed on a consensus map of 1541 cM with 43 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 >36% of the phenotypic variation, indicating that the inheritance of day-neutrality is likely a polygenic trait.Two primary types of commercial strawberries are grown, short-day (SD) and day-neutral (DN). SD genotypes or Junebearers, initiate flower buds either under SD conditions (<14 h of day length) or at temperatures below 15°C, while DN genotypes are photoperiod insensitive and will initiate flowers under any photoperiod conditions as long as temperatures are moderate (Darrow 1966, Hancock 1999. Dayneutrality was most recently introduced into modern cultivars by Bringhurst and Voth (1984), using a native genotype of F. virginiana (Mill) ssp. glauca (S. Watson) Staudt from the Wasatch Mountains of Utah.To date, the genetics of day-neutrality in strawberries have remained elusive. Several different models have been proposed including: (i) regulation by a single dominant gene Voth 1978, Ahmadi et al. 1990); (ii) regulation by dominant complementary genes (Ourecky and Slate 1967); and (iii) quantitative inheritance (Powers 1954, Hancock et al. 2001). The reason why these studies generated different hypotheses may be that they utilized different sets of parents and were conducted in different environments. The study of Ourecky and Slate (1967) was conducted in New York using material that had not recently had any new F. virginiana germplasm incorporated. The studies of Powers (1954) and Hancock et al. (2001), were performed in Wyoming and Michigan, respectively, using DN parents that carried genes from F. · ananassa and wild clones of F. virginiana that were different from the Wasatch source. The studies of Bringhurst and Voth (1978) and Ahmadi et al. (1990) were performed in CA using University of California-Davis breeding parents carrying the Wasatch source of day-neutrality. There was one study in CA that suggested day-neutrality may have a quantitative basis (Shaw 2003), but it was later refuted by a more extensive statistical analysis of a greater number of progeny populations (Shaw and Famula 2005). Sugimoto et al. (2005) found a RAPD-marker linked to a dominant gene regulating day-neutrality in a Japanese breeding population carrying the Wasatch source of day-neutrality.To e...

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Systematic studies of the relative importance of apple traits for U.S. apple producers to inform U.S. apple breeding programs have been lacking. To fill this gap, a series of audience surveys with instant feedback at five apple producer meetings across the United States was conducted. The traits included in this study were fruit crispness, juiciness, firmness, flavor, soluble solids concentration, sugar–acid balance, shelf life at retail, freedom from storage disorders, host plant disease resistance, and other fruit and tree traits provided by the producer. Producers rated fruit flavor and crispness as the most important traits for a successful apple cultivar. The relative importance assigned to traits was associated with growing location and producers’ years of experience in the decision-making process of managing apple orchards. This study contributes directly to a larger effort that provides breeding programs with systematic knowledge of trait preferences of supply chain members, including producers, and should result in a more targeted approach to developing and commercializing new apple cultivars.

Background Consumers purchase fresh strawberries all year long. Extending the fruiting season for new strawberry cultivars is a common breeding goal. Understanding the inheritance of repeat fruiting is key to improving breeding efficiency. Several independent research groups using multiple genotypes and analytic approaches have all identified a single genomic region in strawberry associated with repeat fruiting. Markers mapped to this region were used to evaluate breeding parents from the United States Department of Agriculture – Agricultural Research Service (USDA-ARS) strawberry breeding program at Beltsville, Maryland. Results Markers mapped to repeat fruiting identified once-fruiting genotypes but not repeat-fruiting genotypes. Eleven of twenty-three breeding parents with repeat-fruiting marker profiles were actually once fruiting, indicating at least one additional locus acting epistatically to suppress repeat fruiting. Family segregation ratios could not be predicted reliably by the combined use of parental phenotypes and marker profiles, when using a single-gene model. Expected segregation ratios were calculated for all phenotypic and marker-profile combinations possible from the mapped locus combined with a hypothetical dominant or recessive suppressor locus. Segregation ratios specific to an epistatic suppressor acting on the mapped locus were observed in four families. The segregation ratios for two families were best explained by a dominant suppressor acting on the mapped locus, and, for the other two, by a recessive suppressor. Not all of the observed ratios could be explained by one model or the other, and when multiple families with a common parent were compared, there was no predicted genotype for the common parent that would lead to all of the observed segregation ratios. Conclusions Considering all lines of evidence in this study and others, repeat-fruiting in commercial strawberry is controlled primarily by a dominant allele at a single locus, previously mapped by multiple groups. At least two additional genes, one dominant and one recessive, exist that act epistatically to suppress repeat fruiting. Environmental effects and/or incomplete penetrance likely affect phenotype through the suppressor loci, rather than the primary mapped locus. One of the dominant suppressors acts only in the first year, the year the plant is germinated from seed, and not after the plant has experienced a winter. Electronic supplementary material The online version of this article (10.1186/s12870-019-1984-7) contains supplementary material, which is available to authorized users.

The primary goal of this research was to evaluate the relative importance of strawberry fruit quality and plant traits to strawberry producers. Previous studies focus on strawberry traits that impact postharvest quality and marketable yield; however, studies emphasizing the importance of these traits to strawberry producers are scarce. To investigate U.S. strawberry producer trait preferences, a series of audience surveys were conducted at four strawberry producer meetings across the United States. Results indicate that fruit firmness, fruit flavor, and fruit shelf life at retail were the most important fruit/plant traits to producers for a successful strawberry cultivar to possess. Growing state and producers’ years involved in the decision-making process of strawberry farms impacted the relative importance of the fruit/plant traits. This study directly contributes to a larger investigation of supply chain members’ trait preferences to improve the efficiency of Rosaceae fruit crop breeding programs and to increase the likelihood of new cultivar adoption. The overall project should result in a more efficient approach to new strawberry cultivar development and commercialization.

BACKGROUND: Understanding the genetics of flowering in the strawberry (Fragaria × ananassa) will aid in the development of breeding strategies. OBJECTIVE: To search for quantitative trait loci (QTL) associated with remontancy and weeks of flowering in the strawberry. METHODS: Previously collected phenotypic data from two non-remontant 'Honeoye' × remontant 'Tribute' strawberry populations and simple sequence repeats (SSR) markers were used to search for QTL associated with repeat flowering, weeks of flowering and runner production, as well as the ability to produce flowers and runners at 17, 20 and 23 • C. RESULTS: As was discovered in other studies, we found a major QTL that regulated remontancy and weeks of flowering on homeologous linkage group IV of 'Tribute'. This QTL also had a negative effect on runner production and a positive influence on flower production under high temperatures. A number of additional QTL were discovered that significantly (LOD >3.0) influenced flower and runner production. CONCLUSIONS: Remontancy/non-remontancy is controlled by a major gene/locus and several minor modifying ones.