Olive (Olea europaea L.) is a wind-pollinated, allogamous species that is generally not considered to be self-compatible. In addition, cross-incompatibilities exist between cultivars that can result in low fruit set if compatible pollinisers are not planted nearby. In this study, microsatellite markers were used to identify 17 genotypes that were potential pollen donors in a commercial olive orchard. DNA typing with the same primers was also applied to 800 olive embryos collected from five cultivars in the grove over 2 years of study. Pollen donors for the cultivars Barnea, Corregiola, Kalamata, Koroneiki, and Mission were estimated by paternity analysis, based on the parental contribution of alleles in the genotypes of the embryos. The exclusion probability for the marker set was 0.998 and paternity was assigned on the basis of the 'most likely method'. Different pollen donors were identified for each of the maternal cultivars indicating that cross-compatibilities and incompatibilities varied between the genotypes studied. Cross-pollination was the principal method of fertilization, as selfing was only observed in two of the embryos studied and both of these were from the cultivar Mission. This is the first report where these techniques have been applied to survey the pollination patterns in an olive grove. The results indicate that careful planning in orchard design is required for efficient pollination between olive cultivars.

No abstract

No abstract

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.

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.