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A novel analytical method using fast gas chromatography-surface acoustic wave detection (FGC-SAW) was employed to rapidly characterize blueberry volatile profiles according to genotypes and fruit maturity. Fourteen FGC-SAW peaks were observed and 11 peaks were tentatively identified in the 15 s chromatogram. Peak identifications were confirmed by matching retention index values with similar values from GC-MS analyses of the same samples. Eighty peaks were observed in the 40 min GC-MS analysis of identical samples. Principal component analysis (PCA) score plots of FGC-SAW and GC-MS data both differentiated blueberries according to genotype, maturity stage, and harvest date even though FGC-SAW PCA's used far fewer peak area values. PCA plots clearly separated 'FL02-40', 'Snowchaser', 'Jewel', and 'Primadonna' blueberry cultivars into four quarters using two-dimensional PCA projections. FGC-SAW was also successful in differentiating three berry maturity stages in PCA score plots for both 'Jewel' and 'Primadonna' cultivars. FGC-SAW is an effective technique for rapid analysis of major blueberry volatiles, but could not determine many mid- and low-level volatiles as they were often coeluted with higher concentration volatiles.

Fruit consumption in the UK, particularly of berry fruits, is expanding rapidly and consumer demand for blueberries (Vaccinium spp.) is at record levels with UK growers unable to meet current demand. Consumers are aware that eating fruit can be pleasurable and with appropriate packaging, convenient, but blueberry remains unfamiliar to a wide cross section of UK consumers. There is great potential for UK growers to supply high quality fresh blueberries across a wide season so that consumption of this healthy fruit can be integrated into the British diet. A genetic framework for future crop improvement is required to develop a thriving and sustainable industry. The genetic component of this project builds on the statistical developments derived from the software program, TetraploidMap, to identify fruit quality, health, and agronomic-related quantitative trait loci in tetraploid blueberry for marker assisted breeding.

The tetraploid species in Vaccinium section Cyanococcus and tetraploid V. uliginosum in section Vaccinium are autotetraploid. The same is probably true of the tetraploid species in other sections o...

The volatile composition of four southern highbush blueberry cultivars ('Primadonna', 'Jewel', 'Snowchaser', and 'FL02-40') grown in two locations (Gainesville and Haines City, FL) and harvested multiple times was investigated. A total of 42 volatiles were identified, including 8 esters, 12 terpenoids, 11 aldehydes, 7 alcohols, and 4 ketones. Twelve of these volatiles are reported for the first time in highbush blueberries, with 10 being positively identified: (Z)-3-hexenal, (E,E)-2,4-hexadienal, (E,Z)-2,6-nonadienal, (E,E)-2,4-nonedienal, methyl 2-methylbutanoate, butyl acetate, 2-methylbutyl acetate, and geranyl acetate. The dominant volatiles were aldehydes followed by terpenoids and esters, with distinct varietal profiles. 'Primadonna' was characterized by a large amount of esters and C-6 aldehydes. In contrast, fewer than 4 esters were found in 'FL02-40' and 'Snowchaser', respectively, but they produced more terpenoids than 'Primadonna' and 'Jewel'. Location and/or harvest date affected the production of volatiles in 'Primadonna', but not so much in the other cultivars.

Sweet cherry (Prunus avium) is a member of the Rosaceae family, with a gametophytic self-incompatibility system that strongly affects pollination and fruit set. Alleles at the S-locus control this system, and fertilization does not occur if the S-allele of a haploid pollen gamete matches either S-allele of the diploid maternal pistil. To produce fruit, self-incompatible cherry trees require nearby cross-compatible trees with synchronous flowering. In cherry orchards, two or more cross-compatible pollinizer cultivars are therefore usually inter-planted with the main cultivar. Fortunately, self-compatibility exists, the result of a mutation of one of the alleles at the S-locus, permitting the breeding of self-compatible cultivars that do not require pollinizer trees. The Washington State University (WSU) sweet cherry breeding program seeks to produce self-compatible cultivars (in addition to superior fruit quality and other trait improvements) and desires an early detection system for self-compatible seedlings. PCR-based S-genotyping that included primers for detecting self-compatibility was conducted for 243 seedlings from crosses made in 2004 that initiated this modern breeding program. While self-compatible seedlings were identified, a large proportion of seedlings resulted from unintended parentage, with implications for future breeding strategies.

Maximizing fruit size is critical for profitable sweet cherry (Prunus avium L.) production. Yet, despite its importance, little is known about the genetic control of fruit size. The objective of this study was to identify quantitative trait loci (QTLs) for fruit size and two essential components of fruit size, mesocarp cell number and size. This study utilized a double pseudo-testcross population derived from reciprocal crosses between a sweet cherry cultivar with ~8 g fruit, “Emperor Francis” (EF), and a wild forest sweet cherry selection with ~2 g fruit, “New York 54” (NY). A total of 190 F1 progeny previously utilized for the construction of the linkage maps were evaluated in 2006 and 2007 for fruit weight, length, and diameter; mesocarp cell number and length; and pit length and diameter. In 2008, a subset of this population was again evaluated for fruit weight. Correlation analysis revealed that the three fruit size traits were highly correlated with each other, and mesocarp cell number, not cell length, was correlated with fruit size. Three QTLs were identified for each fruit size trait, and one QTL was identified for mesocarp cell number. Fruit size QTLs were found on linkage group 2 on the EF map (EF 2) and linkage groups 2 and 6 on the NY map (NY 2 and NY 6). On EF 2, the cell number QTL clustered with the fruit size QTL, suggesting that the underlying basis of the fruit size increase associated with this QTL was an increase in mesocarp cell number. On NY 6, pit length and diameter QTLs clustered with those for fruit size, suggesting that the underlying morphological basis of this fruit size QTL is the difference in pit size.

Linkage maps of the sweet cherry cultivar ‘Emperor Francis’ (EF) and the wild forest cherry ‘New York 54’ (NY) were constructed using primarily simple sequence repeat (SSR) markers and gene-derived markers with known positions on the Prunus reference map. The success rate for identifying SSR markers that could be placed on either the EF or NY maps was only 26% due to two factors: a reduced transferability of other Prunus-species-derived markers and a low level of polymorphism in the mapping parents. To increase marker density, we developed four cleaved amplified polymorphic sequence markers (CAPS), 19 derived CAPS markers, and four insertion–deletion markers for cherry based on 101 Prunus expressed sequence tags. In addition, four gene-derived markers representing orthologs of a tomato vacuolar invertase and fruit size gene and two sour cherry sorbitol transporters were developed. To complete the linkage analysis, 61 amplified fragment length polymorphism and seven sequence-related amplified polymorphism markers were also used for map construction. This analysis resulted in the expected eight linkage groups for both parents. The EF and NY maps were 711.1 cM and 565.8 cM, respectively, with the average distance between markers of 4.94 cM and 6.22 cM. A total of 82 shared markers between the EF and NY maps and the Prunus reference map showed that the majority of the marker orders were the same with the Prunus reference map suggesting that the cherry genome is colinear with that of the other diploid Prunus species.

Progress in the rate of improvement in autopolyploid species has been limited compared with diploids, mainly because software and methods to apply advanced prediction and selection methodologies in autopolyploids are lacking. The objectives of this research were to (i) develop an R package for autopolyploids to construct the relationship matrix derived from pedigree information that accounts for autopolyploidy and double reduction and (ii) use the package to estimate the level and effect of double reduction in an autotetraploid blueberry breeding population with extensive pedigree information. The package is unique, as it can create A-matrices for different levels of ploidy and double reduction, which can then be used by breeders to fit mixed models in the context of predicting breeding values (BVs). Using the data from this blueberry population, we found for all the traits that tetrasomic inheritance creates a better fit than disomic inheritance. In one of the five traits studied, the level of double reduction was different from zero, decreasing the estimated heritability, but it did not affect the prediction of BVs. We also discovered that different depths of pedigree would have significant implications on the estimation of double reduction using this approach. This freely available R package is available for autopolyploid breeders to estimate the level of double reduction present in their populations and the impact in the estimation of genetic parameters as well as to use advanced methods of prediction and selection.

It is well documented that blueberry phenolic compositions, such as phenolic acids and flavonoids differ based on species and cultivars. However, phenolic compositions in Florida blueberries have been little explored. Information on Florida blueberries are of interest as they are harvested earlier than other areas of the United States, which may result in compositional differences due to shorter daylight hours and cooler temperatures. Samples were harvested from University of Florida grower-cooperator farm near Gainesville, FL. After liquid-liquid extraction and C-18 SPE cartridge purification, concentrations of phenolic acids and flavonoids of twenty two blueberry cultivars (20 highbush and 2 rabbiteye) were measured using HPLC. Five phenolic acids (gallic acid, protocatechuic acid, chlorogenic acid, caffeic acid and ferulic acid), two flavan-3-ols (catechin and epicatechin) and five flavonols (quercetin-3-galactoside or quercetin-3-glucoside, quercetin-3-arabinoside, myricetin, quercetin and kaempferol) were identified and quantified. Chlorogenic acid was the major component in highbush blueberries. Flavonoid and phenolic acid composition were profoundly different among Florida blueberries and these differences have not been previously reported. The first two components of PCA explained 95% of the variation totally; it showed clear differentiation of blueberry cultivars based on phenolic composition. The majority of the variation between the cultivars was due to variation in quercetin-3-galactoside or glucoside, quercetin-3-arabinoside and chlorogenic acid, which are most likely due to genetic and maturity differences. Complete-linkage clustering analysis displayed five significantly different (p

Understanding the genetic control of fruit size in sweet cherry (Prunus avium L.) is critical for maximizing fruit size and profitable fresh market production. In cherry, coordinated cycles of cell division and expansion of the carpel result in a fleshy mesocarp that adheres to a stony endocarp. How these structural changes are influenced by differing genetics and environments to result in differing fruit sizes is not known. Thus, the authors measured mesocarp cell length and cell number as components of fruit size. To determine the relative genotypic contribution, five sweet cherry cultivars ranging from '1 to 13 g fresh weight were evaluated. To determine the relative environmental contribution to fruit size, different-size fruit within the same genotype and from the same genotype grown in different environments were evaluated. Mesocarp cell number was the major contributor to the differences in fruit equatorial diameter among the five sweet cherry cultivars. The cultivars fell into three significantly different cell number classes: '28 cells, '45 cells, and '78 cells per radial mesocarp section. Furthermore, mesocarp cell number was remarkably stable and virtually unaffected by the environment as neither growing location nor physiological factors that reduced final fruit size significantly altered the cell numbers. Cell length was also significantly different among the cultivars, but failed to contribute to the overall difference in fruit size. Cell length was significantly influenced by the environment, indicating that cultural practices that maximize mesocarp cell size should be used to achieve a cultivar's fruit size potential. The mature cherry fruit is composed of a thin protective exocarp, a fleshy mesocarp, and an inedible stony endocarp (pit) surrounding the seed (Esau, 1977). All three tissue types arise from the ovary, and the increase in fruit size results from a coordinated series of cell divisions and expansions. Fruit diameter increase in sweet cherry follows a double-sigmoid growth curve, consisting of three distinct growth stages (Coombe, 1976). Stage I is characterized by rapid and expo- nential fruit growth following anthesis; stage II, by a lag period of fruit growth coinciding with endocarp hardening and embryo development; and stage III, by a second period of exponential fruit growth ending with either harvest or physiological maturity. During stage I, mesocarp growth consists of both cell division and cell enlargement, whereas stage III mesocarp growth is predominantly the result of cell expansion (Coombe, 1976; Tukey and Young, 1939). Although the growth curve for cherry is well defined, the genetic differences in cell division and enlargement contribut- ing to the wide range in fruit size that can occur between genotypes are not. Wild forms of forest sweet cherry have small

Breeding for a subjective goal such as flavor is challenging, as many blueberry cultivars are grown worldwide, and identifying breeding targets relating to blueberry flavor biochemistry that have a high degree of genetic control and low environmental variability are priorities. A variety of biochemical compounds and physical characters induce the sensory responses of taste, olfaction, and somatosensation, all of which interact to create what is perceived flavor. The goal of this study was to identify the flavor compounds with a larger genetic versus environmental component regulating their expression over an array of cultivars, locations, and years. Over the course of three years, consumer panelists rated overall liking, texture, sweetness, sourness, and flavor intensity of 19 southern highbush blueberry (Vaccinium corymbosum hybrids) genotypes in 30 sensory panels. Significant positive correlations to overall liking of blueberry fruit (P

Most sweet cherry (Prunus avium L.) cultivars grown commercially in the Pacific Northwestern states of the United States are susceptible to powdery mildew, caused by the fungus Podosphaera clandestina (Wall.:Fr.) Lev. The disease is prevalent in the irrigated arid region east of the Cascade Mountains in Washington State. Little is known about genetic resistance to powdery mildew in sweet cherry, although a selection (PMR-1) was identified at Washington State Univ.'s Irrigated Agriculture Research and Extension Center that exhibits apparent foliar immunity to the disease. The objective of this research was to determine the inheritance of powdery mildew resistance from PMR-1. Reciprocal crosses were made between PMR-1 and three high-quality, widely-grown susceptible cultivars (`Bing', `Rainier', and `Van'). Resultant progenies were screened for reaction to powdery mildew colonization using a laboratory leaf disk assay. Assay results were verified by natural spread of powdery mildew among the progeny in a greenhouse and later by placing them among infected trees in a cherry orchard. Segregation within the progenies for powdery mildew reaction fit a 1 resistant: 1 susceptible segregation ratio (P ≤ 0.05), indicating that resistance to powdery mildew derived from PMR-1 was conferred by a single gene.

A personal computer-based method was compared with standard visual assessment for quantifying colonization of sweet cherry (Prunus avium L.) leaves by powdery mildew (PM) caused by Podosphaera clandestina (Wallr.:Fr.) Lev. Leaf disks from 14 cultivars were rated for PM severity (percentage of leaf area colonized) by three methods: 1) visual assessment; 2) digital image analysis; and 3) digital image analysis after painting PM colonies on the leaf disk. The third technique, in which PM colonies on each leaf disk were observed using a dissecting microscope and subsequently covered with white enamel paint, provided a standard for comparison of the first two methods. A digital image file for each leaf disk was created using a digital flatbed scanner. Image analysis was performed with a commercially available software package, which did not adequately detect slight differences in color between PM and sweet cherry leaf tissue. Consequently, two replicated experiments revealed a low correlation between PM image analysis and painted PM image analysis (r2 = 0.66 and 0.46, P ≤ 0.0001), whereas visual assessment was highly correlated with painted PM image analysis (r2 = 0.88 and 0.95, P ≤ 0.0001). Rank orders of the 14 cultivars differed significantly (P ≤ 0.05) when PM image analysis and painted PM image analysis were compared; however, rankings by visual assessment were not significantly different (P > 0.05) from those by painted PM image analysis. Thus, standard visual assessment is an accurate method for estimating disease severity in a leaf disk resistance assay for sweet cherry PM.

A detached leaf disk assay for screening sweet cherry ( Prunus avium L.) genotypes for susceptibility to powdery mildew (PM) (Podosphaera clandestina (Wallr.:Fr.) Lev.) was developed by evaluating the effects of photoperiod (24 hours light, 0 hours light, 14 hours light/10 hours dark), substrate nutrient content (sterile distilled water, 1% sucrose), leaf age (old, young, emergent), and leaf explant size (intact leaf, 30 mm, 20 mm) on PM growth on leaves from the susceptible cultivar Bing. The only parameter described that had a significant (P ≤ 0.001) effect on PM growth was leaf age. Old leaves, designated as the third fully expanded leaf from the basal end of current-year's shoot growth, were never infected with PM under controlled inoculations. In the absence of significant differences between treatments, those parameters with the highest treatment means were selected for subsequent evaluation. To test the leaf disk assay, 14 sweet cherry cultivars were screened in two experiments, and rated according to level of PM susceptibility. Rank sum comparison of results from cultivars used for leaf disk screening agreed with earlier field rankings of the same cultivars. The developed leaf disk assay greatly reduced the space required to screen sweet cherry cultivars, and was a repeatable and objective predictor of field resistance that may be useful for screening germplasm or breeding populations. trees (Grove and Boal, 1991a). These cleistothecia serve as the primary inoculum source. Infections in eastern Washington are first observed in late April to mid-May, ≈4 to 6 weeks after budbreak. Initially, PM appears as light-colored lesions on leaves, generally in the inner portions of the canopy. Developing colonies are white, and eventually cause blis- tering and leaf deformation. Young, vigorous shoots are infected most often, resulting in stunted growth. Foliar incidence of PM in- creases through May and June, with rapid increases in secondary inoculum (i.e., conidia of the pathogen). Foliar PM continues to be severe after harvest, partly because Washing- ton growers stop fungicide applications im- mediately before harvest (Grove, 1998). Podosphaera clandestina is controlled with sterol-inhibiting fungicides. However, recent reports identified site-specific incidences of P. clandestina resistant to fenarimol ( α-(2

The Florida blueberry industry has grown rapidly because Florida growers can produce high-quality fruit when few fresh berries are available and berry prices are high. Although southern highbush blueberry acreage has expanded significantly in Florida, Georgia, California, and Mexico during the last several years, better cultivars and improved cultural practices have increased grower production efficiency during the last several years, with promising production trends for the future profitability. This revised 4-page fact sheet was written by J. G. Williamson, J. W. Olmstead, and P. M. Lyrene, and published by the UF Department of Horticultural Sciences, February 2012. HS742/AC031: Florida's Commercial Blueberry Industry (ufl.edu)

Before beginning a discussion about the future of plant breeding training, it is necessary to defi ne what a plant breeder is. The traditional view of plant breeders includes only those researchers who develop new plants that result in a product more suited to human needs. However, many feel that this defi nition should be expanded to include scientists who contribute to crop improvement through any type of genetic studies. These studies range from using molecular markers to describe levels of diversity in a breeding population to identifying the QTL that underlie variation patterns. In this discussion of plant breeding training we will use the more restricted defi nition to single out the training of those individuals who directly produce new cultivars.

Most sweet cherry (Prunus avium L.) cultivars grown commercially in the United States are susceptible to powdery mildew, caused by the fungus Podosphaera clandestina (Wall.:Fr.) Lev. Recently, hybrid populations segregating for resistance to powdery mildew were developed by crossing a mildew-resistant sweet cherry selection, PMR-1, with the susceptible cultivars Bing, Rainier, and Van. Although segregation within these populations indicated a single gene was responsible for the powdery mildew resistance conferred by PMR-1, the gene action could not be determined. Therefore, a reciprocal cross between `Bing' and `Van' was made to determine the allelic state of the susceptible parents used previously. All progeny (n = 286) from this cross were susceptible to powdery mildew. This information, combined with results from previous segregation data, indicate the powdery mildew resistance gene is inherited in a dominant manner and is present in PMR-1 in the heterozygous allelic state. We have named this gene Pmr1. Furthermore, in combination with known pedigree information, we have been able to predict the susceptibility of more than 60 additional commercial and recently released sweet cherry cultivars.

Although maximizing fruit size is critical for profitable sweet cherry (Prunusavium L.) production, little is known about the cellular differences among and between cultivars that contribute to fruit size differences. A wide range of fruit size exists among sweet cherries, and, due to cultural and environmental differences, significant variation exists among genetically identical fruit from the same cultivar. To determine the relative contributions of flesh cell number and cell size to final fruit size in sweet cherry, equatorial sections of three cultivars with a wide range in final average fruit size [`New York 54' (NY54; 1.4 g fresh weight, 11.8 mm diameter), `Emperor Francis' (EF; 6.1 g, 21.0 mm), and `Selah' (12.8 g, 25.5 mm)] were created from mature fruit. Cells intersecting a transverse line were counted and average cell length was calculated. The average cell numbers were significantly different (P ≤ 0.05) between `NY54', `EF', and `Selah' (26.7, 47.4, and 83.2, respectively), indicating that flesh cell number is the major contributor to differences in fruit size between cultivars. Flesh cell numbers of `NY54', `EF', and `Selah' were similar at bloom and increased rapidly for a short duration after fertilization, suggesting a key developmental period for fruit size differences. To determine the contribution of cell number differences to variation in fruit size within a cultivar, fruit from `Bing' and `Regina' trees exhibiting a range of size due to cultural and environmental differences were measured. In both cases, average cell number was not significantly different (P = 0.9, P = 0.3, respectively), while average cell size was (P ≤ 0.05), further indicating fruit flesh cell number is a genetically controlled trait.

Most sweet cherry (Prunus avium L.) cultivars grown commercially in the Pacific Northwest U.S. are susceptible to powdery mildew caused by the fungus Podosphaera clandestina (Wall.:Fr.) Lev. The disease is prevalent in the irrigated arid region east of the Cascade Mountains in Washington State. Little is known about genetic resistance to powdery mildew in sweet cherry, although a selection (`PMR-1') was identified at the Washington State Unive. Irrigated Agriculture Research and Extension Center that exhibits apparent foliar immunity to the disease. The objective of this research was to characterize the inheritance of powdery mildew resistance from `PMR-1'. Reciprocal crosses between `PMR-1' and three high-quality, widely-grown susceptible cultivars (`Bing', `Rainier', and ëVaní) were made to generate segregating progenies for determining the mode of inheritance of `PMR-1' resistance. Progenies were screened for susceptibility to powdery mildew colonization using a laboratory leaf disk assay. Assay results were verified by natural spread of powdery mildew among the progeny seedlings in a greenhouse and later by placement among infected trees in a cherry orchard. Progenies from these crosses were not significantly different (P > 0.05) when tested for a 1:1 resistant to susceptible segregation ratio, indicating that `PMR-1' resistance is conferred by a single gene, which we propose to designate as PMR-1.