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A growing number of metagenomics-based approaches have been used for the discovery of viruses in insects, cultivated plants, and water in agricultural production systems. In this study, sixteen blueberry root transcriptomes from eight clonally propagated blueberry plants of cultivar ‘Emerald’ (interspecific hybrid of Vaccinium corymbosum and V. darrowi) generated as part of a separate study on varietal tolerance to soil salinity were analyzed for plant viral sequences. The objective was to determine if the asymptomatic plants harbored the latent blueberry red ringspot virus (BRRV) in their roots. The only currently known mechanism of transmission of BRRV is through vegetative propagation; however, the virus can remain latent for years with some plants of ‘Emerald’ never developing red ringspot symptoms. Bioinformatic analyses of ‘Emerald’ transcriptomes using de novo assembly and reference-based mapping approaches yielded eight complete viral genomes of BRRV (genus Soymovirus, family Caulimoviridae). Validation in vitro by PCR confirmed the presence of BRRV in 100% of the ‘Emerald’ root samples. Sequence and phylogenetic analyses showed 94% to 97% nucleotide identity between BRRV genomes from Florida and sequences from Czech Republic, Japan, Poland, Slovenia, and the United States. Taken together, this study documented the first detection of a complete BRRV genome from roots of asymptomatic blueberry plants and in Florida through in silico analysis of plant transcriptomes.

Blueberry (Vaccinium spp.) plants are exposed to existing and emerging viruses as a result of expanding acreage of blueberry plantations across the world, primarily in North America. Since blueberry is cultivated in areas where there are wild Vaccinium spp., there is increasing risk of virus movement between wild and cultivated blueberries. This is theoretically possible because viruses can spread from commercial cultivars to native species and vice versa causing the spread of existing and new viruses. The occurrence of these viruses in blueberry can be devastating to the industry considering the cost for cultivation and production of this perennial crop. However, the advent of high-throughput sequencing and bioinformatic sequence analysis have allowed for rapid identification of known and novel viruses in any crop including blueberry, thus facilitating proper intervention in response to serious viral diseases. In this paper, we aim to focus on the current status of known and novel viruses emerging in blueberry worldwide, which may impact the blueberry industry.

Blueberry (Vaccinium spp.) is a specialty crop with expanding production and consumption worldwide. Southern Highbush Blueberries (SHB) require few chilling hours and include early-ripening cultivars which can be harvested in an early market window making the crop more profitable for growers in sub-tropical regions. To expand the marketability of the crop, fruit breeders are seeking to meet the current demand for fruit quality. To this end, this study gathered sensory measurements (firmness, sweetness, sourness, blueberry flavor, green flavor and off-flavors), chemical (pH, titratable acidity and soluble solids concentration), and physical attributes (compression force) on six SHB cultivars, in order to understand how fruit quality traits are affected by environmental conditions such as storage duration, year and harvest date. Differences across environmental conditions for all attributes were observed. Indigocrisp and Keecrisp were the firmest cultivars and maintained firmness over time in storage. Additionally, Indigocrisp was the sweetest and had the most blueberry and green flavors among the cultivars. On the other hand, Arcadia was the softest, as measured by sensory and compression force, but varied with year and harvest. Arcadia and Emerald were the least sweet and most sour of the cultivars, and Endura and Patrecia were intermediate for all sensory attributes. In general, sensory descriptors were well explained by instrumental measurements. Variations across seasons and storage were inconsistent among cultivars, but Indigocrisp was the most stable cultivar for the quality traits evaluated. In the end, all fruit quality traits assayed in this study were influenced by environmental conditions throughout the season.

The average American child eats fewer fruits than recommended. Although taste is the primary motivator for food intake among children, little research has systematically measured children's liking of fruit and determined whether their preferences differ from adults. We phenotyped 49 children and their mothers to determine: (1) their liking of the taste of 3 blueberry cultivars (“Arcadia,” “Keecrisp,” and “Kestrel”) from 2 harvests for which total soluble solids were determined using a handheld Brix refractometer; (2) the association between liking and blueberry sugar content; and (3) the most preferred level of fructose, one of the primary sugars in blueberry fruit. Multiple methods, identical for all participants, assessed which cultivar they liked best. Dietary intake, determined via 24‐h dietary recall, revealed most children (73%) and adults (92%) did not meet dietary guidelines for fruit intake. We found that during the 1st harvest, Keecrisp was sweeter by 4° Brix than either Arcadia or Kestrel and was the cultivar most preferred by both children and adults. For the 2nd harvest, mothers liked each of the cultivars equally, but children preferred Arcadia, which was 2° Brix sweeter than the other 2 cultivars. Like other sugars, children's most preferred concentration of fructose was significantly higher than that of adults. In sum, children appear to be more sensitive to smaller variations in sweetness than are adults. Identifying drivers of fruit preference and assessing children's liking for whole fruits are important steps in developing strategies to increase fruit consumption among children. Although taste is the primary motivator for food intake among children, little research has systematically measured children's liking of fruit and determined whether their preferences differ from adults. In this farm‐to‐sensory‐lab study, we used multiple methods to assess liking for the taste of 3 blueberry cultivars picked during the beginning of the Florida blueberry season. We found that children prefer higher levels of fructose and appear to be more sensitive to small changes in the sugar content of blueberry fruit than did adults. These findings provide insight into the child consumer and highlights the potential for consumer‐driven breeding to produce fruit accepted by young children.

The rate-limiting step in the iron uptake mechanism of strategy-I plants is ferric chelate reductase (FCR)-mediated iron reduction. Southern highbush blueberry (SHB, Vaccinium corymbosum L. interspecific hybrids) is a specialty crop that commonly exhibits iron deficiency in agricultural soils due to its low FCR activity. Extracellular iron reduction has been reported in some fungi and peronosporomycetes (subsequently referred to as oomycetes), and this has the potential to increase iron reduction capacity in the rhizosphere and impact plant iron uptake. Here, we isolated and identified fungi and oomycetes from the roots and nutrient solution of hydroponically grown SHB. Then, we built a consortium of iron-reducing microorganisms and used this to study the iron nutrition of inoculated and non-inoculated SHB plants in vitro and ex vitro . We found isolates of nine fungal species and the oomycete Pythium irregulare complex, all of which exhibited detectable levels of extracellular iron reduction. Isolates of Alternaria alternata, Bjerkandera adusta , and Pythium irregulare exhibited extracellular iron reduction that was equal to or higher than that of SHB roots, and they were used to create a microbial consortium for the inoculation experiments. In vitro , inoculation with a consortium of iron-reducing microorganisms did not affect iron reduction capacity in the SHB rhizosphere under iron deficiency conditions, but it increased iron reduction capacity in the SHB rhizosphere under iron abundance conditions. Nevertheless, inoculation treatments generally decreased SHB iron uptake from the medium. Ex vitro , inoculation with a consortium of iron-reducing microorganisms did not affect iron reduction capacity in the SHB rhizosphere. In all experiments, the inoculation treatment did not increase leaf active iron concentration. Altogether, our results suggest that inoculation with iron-reducing microorganisms is not a viable alternative for enhancing SHB iron nutrition.

Vaccinium arboreum Marsh is a wild species adapted to high pH (above 6.0) and low organic matter soils (below 2.0%). The use of V. arboreum rootstocks may be a viable option to increase soil adaptation of southern highbush blueberry (SHB) (Vaccinium corymbosum interspecific hybrid) under marginal soil conditions. The objective of this research was to evaluate the vegetative and reproductive traits of ‘Farthing’ and ‘Meadowlark’ SHB own-rooted or grafted onto V. arboreum and grown in pine bark–amended or nonamended soil. The study was conducted from 2012 through 2014 at a research center in Citra, FL, and a grower’s farm in Archer, FL. Vaccinium arboreum rootstock generally induced the same effects in both cultivars. Grafted plants in both soil treatments had reduced canopy growth in the first year after field planting compared with own-rooted plants in amended soil. However, canopy volume of grafted plants was greater than own-rooted plants in nonamended soil and similar to own-rooted plants in amended soil 2 years after field planting for ‘Meadowlark’ and 3 years after planting for ‘Farthing’. Fruit yield was lower in grafted plants compared with own-rooted plants in the first fruiting year (2 years after field planting). By the second fruiting year, yields of grafted plants were similar to or greater than yields of own-rooted plants when grown in nonamended soil, whereas in amended soil, yields of grafted plants were similar to yields of own-rooted plants. Grafted plants had greater mean berry weight, but lower berry firmness; however, the firmness values were still considered acceptable (greater than 160 g⋅mm−1). Internal fruit quality [total soluble solids (TSS) and total titratable acidity (TTA)] was not consistently affected by the rootstock or soil treatments. These results suggest that grafting SHB onto V. arboreum does not increase yield in the establishment years compared with own-rooted SHB when grown in amended soils, but may have the ability to increase yield with no negative effects on fruit quality when grown in nonamended soils.

Most commercially important rootstocks for peach [Prunus persica (L.) Batsch] had been selected for resistance to one or more of the root-knot nematode (RKN) species: Meloidogyne incognita, M. arenaria, and M. javanica. The peach root-knot nematode, M. floridensis (MF), is a relatively newly discovered threat to peach and is not controlled by resistance genes in “Nemared,” “Nemaguard,” and “Okinawa.” The “Flordaguard” peach seedling rootstock, conventionally bred to provide resistance to MF, has solely been used for low-chill peach production in Florida for over 20 years and has already shown signs of resistance breakdown. A source of high resistance to the pathogenic MF isolate (“MFGnv14”) was identified from wild peach Prunus kansuensis Rehder (Kansu peach), thereby suggesting the potential for broadening spectrum and increasing durability of resistance in peach rootstocks through interspecific hybridization with P. kansuensis. Using 12 F2 and BC1F1 populations derived from crosses between Okinawa or Flordaguard peach and P. kansuensis populations, we examined the genetic control for MF resistance by identifying associated microsatellite markers and determining genomic location of the resistance locus. One microsatellite marker (UDP98-025) showed strong and consistent association with resistance based on root-galling index. The resistance locus was mapped on the subtelomeric region of linkage group 2, co-localizing with other previously reported RKN resistance genes in Prunus. Segregation of gall-index-based resistance observed in F2 and BC1F1 populations is compatible with the involvement of a multiallelic locus wherein a dominant (Mf1) or recessive (mf3) resistance allele is inherited from P. kansuensis, and susceptibility alleles (mf2) from peach.

A family of the cross of the northern highbush blueberry ‘Draper’ × the southern highbush ‘Jewel’ (D × J) was propagated and phenotyped for plant size, yield, rate of flower, bud, and fruit development, leafing ability, winter hardiness, and fruit quality for 2 years in the field in Florida (FL), Georgia (GA), Michigan (MI), and Oregon (OR). In addition, a controlled greenhouse study was conducted on these progenies to estimate their chilling requirements. Significant levels of genotypic variability were observed for all the traits and the majority showed significant location and genotype × environmental interactions. Most of these traits were normally distributed across genotypes. There were many more flower buds per cane in GA than FL and OR, and many more vegetative buds broke in OR than in the southeastern states. Most of the various yield and growth traits were significantly correlated, except for flower buds per cane with plant height and width, and strength of leafing with plant width and flower buds/cane. Plants in OR developed much more slowly than those in FL and GA. There was a significant G × E effect on days to early green tip, floral bud break, and full bloom. Significant correlations were observed between all the developmental rates except between floral bud break and the days to full flowering and first blue fruit. Most individuals were severely damaged by winter cold in MI, although a few showed good tolerance. Significant location effects were observed for pH, titratable acidity (TA), soluble solids (SS), and SS/TA. Fruit in FL were a little softer and had higher SS/TA ratios than those in GA. There were significant interactions between genotype and environment for all the fruit quality traits except for fruit scar, firmness, anthocyanin content (ACY), and % juice. Fruit scar had a significant positive relationship with firmness and a significant negative relationship with flavor. Fruit color was significantly associated positively with soluble solids and ACY. Firmer fruit had significantly lower levels of ACYs. Fruit pH showed significant positive correlations with TA, TA/SS, and % juice, and significant negative relationship with SS and ACY. TA was significantly associated negatively with TA/SS and positively with ACY and % juice. TA/SS and ACY were positively correlated significantly with % juice. Two or three individuals were identified at each location that had high yields, were very early or late ripening and had excellent overall fruit quality. There were significant levels of genotypic, environmental (chilling hours) and G × E interaction among vegetative and floral buds for numbers of buds per shoot, percentage that developed and their developmental rate. The chilling requirement of highbush blueberry appears to be regulated polygenically as the D × J family segregated normally. On average, genotypes did more poorly at 250 and 350 chilling hours than the other chilling treatments.

The U.S. Department of Agriculture, Agricultural Research Service, National Clonal Germplasm Repository (NCGR), Corvallis, Oregon, maintains the national collection for Vaccinium L. germplasm. The NCGR genebank includes more than 1700 accessions, with representatives of 81 Vaccinium taxa from around the world. The primary collection of clonal blueberries and their wild relatives are maintained as plants in containers in greenhouses and screenhouses. While the primary genepool for highbush blueberry (V. corymbosum L.), the main crop of economic importance, is within Section Cyanococcus, breeders wish to expand gene accessibility to include representatives of the rich diversity present in other sections. Knowledge of ploidy level is paramount for this task, but has been limited. The objective of this research was to evaluate ploidy levels of approximately 50 species within the NCGR collection. Ploidy was evaluated through flow cytometry using cell preparations from leaf samples. The base haplotype for Vaccinium is x=12. Many species native to the South Pacific and Southeast Asia were diploid (2n=2x=24). Sections Cyanococcus and Myrtillus each included diploid, tetraploid, and hexaploid members. Section Oxycoccus had diploids and hexaploids. The clones of V. dependens (G. Don) Sleumer (sect. Brachyceratium) and V. poasanum (Donn. Sm.) (synonym = Symphysia poasanum (Donn. Sm.) Vander Kloet) were triploid. Pyxothamnus members from Meso- and South America, V. consanguineum Klotzsch and V. corymbodendron Dunal, were tetraploid. These two species are candidates for direct crosses with V. corymbosum. Ploidy levels from other species representatives and standards are reported.

Vaccinium arboreum (VA) is a wild blueberry species that exhibits wider soil pH tolerance and greater ability for iron and nitrate uptake than cultivated Vaccinium species, including southern highbush blueberry (SHB, V. corymbosum interspecific hybrids). The ability of VA and SHB to respond to iron deficiency by rhizosphere acidification was investigated. Rooted cuttings of the VA genotype FL09-502 and SHB ‘Emerald’ were transplanted to a hydroponic system filled with complete nutrient solution. After 14 days of acclimation at 45 µm iron, plants were transferred to unbuffered nutrient solutions containing 90 or 10 µm iron. ‘Emerald’ and FL09-502 plants grown in 10 µm iron exhibited less iron uptake and lower chlorophyll, total iron, and active iron contents than plants grown in 90 µm iron. Generally, there were no species-level differences in iron or nitrate uptake. Neither FL09-502 nor ‘Emerald’ acidified the rhizosphere in either the nutrient solution or in a gel-based assay, regardless of external iron concentration. A screen of 18 additional genotypes of VA and SHB confirmed that this response is absent in these taxa. Thus, rhizosphere acidification is not part of the iron deficiency response of SHB and VA. In addition, the ability to acidify the soil is not likely to be responsible for the wider soil pH tolerance of VA.

ADDITIONAL INDEX WORDS. floral development, floral initiation, growing degree days, reproductive buds, Vaccinium corymbosum ABSTRACT. Blueberry (Vaccinium spp.) production is increasing worldwide, particularly in subtropical growing regions,butinformationontimingandextentofinflorescence buddevelopmentduringsummerandfallandeffectson bloom the next season are limited. The objectives of this study were to determine time of inflorescence bud initiation, describe internal inflorescence bud development, and determine the relationship between internal inflorescence bud development and bloom period the next spring in two southern highbush blueberry (SHB (Vaccinium corymbosum interspecific hybrids)) cultivars. 'Emerald' and 'Jewel' SHB buds were collected beginning in late summer until shoot growth cessation in late fall for dissection and identification of organ development. Inflorescence bud frequency and number, vegetative and inflorescence bud length and width throughout development, and bloom were also assessed. Inflorescencebud initiation occurred earlier in'Emerald' compared with'Jewel'.Fivestages ofinternal inflorescence bud development were defined throughout fall in both cultivars, ranging from a vegetative meristem to early expansion of the inflorescence bud in late fall. 'Emerald' inflorescence buds were larger and bloomed earlier, reflecting the earlier inflorescence bud initiation and development. Although inflorescence bud initiation occurred earlierin'Emerald'comparedwith'Jewel',thepatternofdevelopmentwasnotdifferent.Timingofinflorescencebud initiation influenced timing of bloom with earlier initiation resulting in earlier bloom.

Background Blueberries are one of the few horticultural crops adapted to grow in acidic soils. Neutral to basic soil pH is detrimental to all commonly cultivated blueberry species, including Vaccinium corymbosum (VC). In contrast, the wild species V. arboreum (VA) is able to tolerate a wider range of soil pH. To assess the molecular mechanisms involved in near neutral pH stress response, plants from pH-sensitive VC (tetraploid) and pH-tolerant VA (diploid) were grown at near neutral pH 6.5 and at the preferred pH of 4.5. Results Transcriptome sequencing of root RNA was performed for 4 biological replications per species x pH level interaction, for a total of 16 samples. Reads were mapped to the reference genome from diploid V. corymbosum, transforming ~55% of the reads to gene counts. A quasi-likelihood F test identified differential expression due to pH stress in 337 and 4867 genes in VA and VC, respectively. Both species shared regulation of genes involved in nutrient homeostasis and cell wall metabolism. VA and VC exhibited differential regulation of signaling pathways related to abiotic/biotic stress, cellulose and lignin biosynthesis, and nutrient uptake. Conclusions The specific responses in VA likely facilitate tolerance to higher soil pH. In contrast, response in VC, despite affecting a greater number of genes, is not effective overcoming the stress induced by pH. Further inspection of those genes with differential expression that are specific in VA may provide insight on the mechanisms towards tolerance. Electronic supplementary material The online version of this article (doi:10.1186/s12864-017-3967-0) contains supplementary material, which is available to authorized users.

BACKGROUND Fruit texture is a primary selection trait in southern highbush blueberry (SHB) breeding to increase fresh fruit postharvest quality and consumer acceptance. A novel crisp fruit texture has recently been identified among SHB germplasm. In this study, we developed a common set of descriptors that align sensory evaluation of blueberry fruit texture with instrumental measures that could be used for quantitative measurements during pre- and postharvest evaluation. RESULTS Sensory and instrumental characteristics were measured in 36 and 49 genotypes in 2010 and 2011, respectively. A trained sensory panel evaluated fresh fruit based on five common textural attributes in 2010 and 2011: bursting energy, flesh firmness, skin toughness, juiciness and mealiness. Instrumental measures of compression and bioyield forces were significantly different among cultivars and correlated with sensory scores for bursting energy, flesh firmness and skin toughness (R > 0.7, except skin toughness in 2011), but correlations with sensory scores for juiciness and mealiness were low (R < 0.4). CONCLUSION The results of sensory and instrumental measures supported the use of both compression and bioyield force measures in distinguishing crisp from standard-texture genotypes, and suggest that crisp texture in SHB is related to the sensory perception of bursting energy, flesh firmness and skin toughness. © 2014 The Authors. Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Light intensity, duration, direction, and wavelength are informative to plants. The biochemical circuits that connect specific light wavelengths to expression of specific genes and the metabolic networks they govern have been well defined. However, little emphasis has been placed on how discrete wavelengths of light, alone or in combination, may be applied to manipulate postharvest qualities of high-value horticultural crops. Using narrow-bandwidth LED light we test the hypothesis that discrete light wavelengths can affect the accumulation of volatile compounds known to affect aroma or taste in select flower and fruit products. Volatile benzenoid/phenylpropanoid emission from petunia flowers could be altered with light application. Levels of a key floral volatile, 2-phenylethanol, increased with a red and far-red light treatment. Similar experiments demonstrated that fruit volatile profiles of tomato, strawberry, and blueberry can be manipulated with specific light treatments. These results suggest that compounds affecting sensory qualities of flowers and fruits can be modified by adjustment of ambient light conditions. These findings open new areas of inquiry about how the fragrance and flavor of flowers and fruits may be improved with simple changes in postharvest light conditions.

Because of financial and labor concerns, growers are interested in using machine harvesting for fruit destined to be fresh marketed. Machine harvest of highbush blueberry (Vaccinium corymbosum) has typically been used to obtain large volumes of fruit destined for processing. Bush architecture, easy detachment of mature berries compared with immature berries, loose fruit clusters, small stem scar, firm fruit, and a concentrated ripening period are breeding goals to develop cultivars amenable to machine harvest. In the University of Florida (UF) southern highbush blueberry [SHB (Vaccinium corymbosum hybrids)] breeding program, sparkleberry (Vaccinium arboreum) has been used in wide crosses in an attempt to introgress traits that may be valuable for machine harvesting, namely upright growth habit with a narrow crown and long flower and fruit pedicels creating loose fruit clusters. Two eras of sparkleberry hybridization experiments have occurred since the early 1980s. The first era used darrow’s evergreen blueberry (Vaccinium darrowii) as a bridge between sparkleberry and tetraploid SHB, with the recently released cultivar FL 01-173 (sold under the trademarked name Meadowlark) as an example of the end product. The second era has used chromosome doubling to develop polyploid sparkleberry selections that were directly crossed with tetraploid SHB. After 1 year of evaluation, a SHB × (SHB × sparkleberry) population developed for linkage and quantitative trait locus mapping showed abundant variation for length:width ratio of the plant, but similarity to the highbush phenotype for peduncle and pedicel length of the fruit. These first evaluations indicate evidence of introgression and provide an initial step toward improved cultivars for mechanical harvesting.

Vaccinium twig blight (caused by Phomopsis vaccinii, teleomorph Diaporthe vaccinii) is a major endemic disease on blueberries and cranberries in the Eastern and Northwestern USA and Canada. It has also been found in Europe, Chile and China. Publications on its occurrence in the USA and Canada indicate that the pathogen is limited to cool climates. Published data on worldwide occurrence were inventoried and supplemented with National Plant Diagnostic Network (NPDN) data in the USA. These occurrence and long-term climate data were entered in the niche models MaxEnt and Multi-Model Framework to predict the potential global distribution of the disease. Precipitation in the driest quarter and mean annual temperature contributed most to the prediction. The results indicate that P. vaccinii is not limited to cool climates, although the optimal annual average temperature is 10 °C according to the MaxEnt model. The models correctly predicted that the climate in the central and eastern USA and the west coast of the USA and Canada would be conducive to blueberry twig blight. Large areas in Europe, eastern Australia and New Zealand, and smaller areas in South America and East Asia would be conducive too. For the first time, the NPDN database was shown to be an important source of information for the prediction of the potential global distribution of a plant pathogen.

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...

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

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.

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.