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Ten seedlings from 36 crosses representing eastern and western North American short day and remontant genotypes were evaluated in 2011 and 2012 in California, Michigan, New Hampshire and Oregon, for phenology, flower related traits, plant characteristics, fruit characteristics and fruit chemistry traits. There was significant variability among genotypes, locations and evaluation year for most of the characteristics; however, few genotype 9 location and genotype 9 year interactions were detected. General combining ability variance components were significant for all traits and greater than SCA variance components for peduncle length, total flowering weeks, flowering cycles, truss size, growing degree days for harvest data, remontancy, achene position, ease of capping, fruit weight, percent soluble solids, titratable acidity and soluble solids/titratable acidity. ‘Sarian’ was identified as the best contributing parent for remontancy. Narrow-sense heritability estimates were moderate to high (0.33–0.78) for total flowering weeks, flowering cycle, truss size, remontancy, number of runners, fruit weight, pH, and titratable acidity. Having a better understanding of these attributes will provide breeders guidance on the most effective breeding strategies for incorporating superior traits from this germplasm into their programs. [ABSTRACT FROM AUTHOR]

Perpetual-flowering (PF) is a highly desirable trait within cultivated strawberries ( Fragaria × ananassa) for the commercial and home garden markets. The most widely used source of the PF trait was originally introgressed from a wild F. virginiana subsp. glauca accession collected in the Wasatch Mountains near Salt Lake City, UT in 1955. This source is conferred by a single dominant QTL, FaPFRU, and was recently identified in multiple bi-parental populations. Multiple markers have been proposed as diagnostic tests for marker-assisted selection (MAS). These markers were proposed after looking at a relatively small sample of germplasm. To identify the best diagnostic testing procedure for MAS, the markers were evaluated individually and in combination on a training set of cultivars with known genotypes and the best test was used to determine the distribution of the FaPFRU source of PF within a large sample of octoploid Fragaria germplasm. Of the tests evaluated, the microsatellite marker Bx215 alone was found to have the best diagnostic ability for MAS with an accuracy of 93.1% in controlled conditions. When utilizing the test on 390 F. × ananassa accessions, 164 accessions were identified to likely have the FaPFRU locus. Nine octoploid Fragaria accessions were PF and did not have this marker, indicating possible recombination events or potentially novel sources of the PF trait. Future work will be needed to dissect the PF trait in these nine individuals. [ABSTRACT FROM AUTHOR]

BACKGROUND: Understanding the genetics of flowering in the strawberry (Fragaria x 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' x 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. [ABSTRACT FROM AUTHOR]

BACKGROUND: Flower initiation in strawberry is often classified by photoperiod sensitivity; however, temperature also plays a major role in determining flower initiation. OBJECTIVE: Our goal was to determine the role heat tolerance plays in regulating remontant flowering in a segregating population of strawberry, Fragaria×ananassa. METHODS: Non-remontant (short day) 'Honeoye' and remontant 'Tribute' were crossed and 54 progeny were grown in three temperature regimes (17, 20, and 23°C) under a long photoperiod in the greenhouse and differences in flower and runner formation among the progeny were compared. In addition, clonally replicated individuals of the same family were grown in the field in Michigan and Oregon, so that the extent of heat tolerance observed for each genotype in the greenhouse studies could be compared to their phenotype in the field (remontant vs. non-remontant). RESULTS: A significant Genotype x Environment interaction was observed in the greenhouse studies, indicating that there was a strong genetic component regulating the response of the individuals to increasing temperature. The level of heat tolerance, as defined as the difference in flower numbers at 23°C vs. 17°C, showed a continuous distribution among the progeny, indicating polygenic control. The majority of the genotypes that were remontant in the field produced more flowers at 23°C than at 17°C in the greenhouse trials. Flower initiation in both the parents was reduced at 23°C, but 'Tribute' produced significantly more flowers than 'Honeoye' at 23°C (48.0 vs. 11.3). Most remontant progeny had few runners, although there were some notable exceptions. CONCLUSIONS: Temperature tolerance plays an important role in the flower and runner initiation of remontant genotypes. Genotypes with high heat tolerance can be selected that will more dependably flower in environments with highly variable levels of summer heat. [ABSTRACT FROM AUTHOR]

Fragaria xananassa Duchesne ex Rozier, or the cultivated strawberry, resulted from the hybridization of two wild species, F. chiloensis (L.) Miller and F. virginiana Miller. In an attempt to recreate the cultivated strawberry, elite clones of F. chiloensis and F. virginiana were crossed within species and then hybridized to produce 26 reconstructed populations. Of these populations, FVC11 [(Frederick 9 x LH 50-4) x (Scotts Creek x 2 MAR 1A)] had unusually large fruit size and was selected for further analysis. In the summer of 2008, 78 individuals of this population were evaluated for their seasonal flowering patterns, inflorescence number,Fragaria xananassa e height, crown production, flower number, fruit size, yield, internal color, soluble solids, fruit firmness, and plant vigor. Progeny means were compared with those of the parental means and most traits exhibited transgressive segregation, most notably yield and fruit weight. Significant positive correlations were found between many of the production traits, although there were significant negative correlations between fruit firmness and flower number per inflorescence, fruit firmness and soluble solids, and yield per plant and soluble solids. Overall performance scores were assigned to each genotype by summing their relative performance for each trait in the population. Individuals were identified that combined high values for fruit weight and yield with higher than average values for fruit color, firmness, and soluble solids. Use of this population in breeding programs could help expand the genetic base of the cultivated strawberry with limited linkage drag. [ABSTRACT FROM AUTHOR]