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- Author or Editor: James J. Luby x
The relationships between cellular characteristics of cortical tissue and changes in texture during storage under controlled atmosphere (CA, 3% O2 + 3% CO2) or air at 0C were studied. The cultivars used were `Delicious', `Cortland', `Honeycrisp' and its parents, `Honeygold' and `Macoun'. The force needed to break a 7-mm cylinder of apple flesh (breaking force) was greatest for `Delicious' and `Honeycrisp'. Scanning electron microscopy demonstrated that tissues of firm-fleshed cultivars (`Honeycrisp' and `Delicious') fractured through cells, while that of soft-fleshed cultivars (`Cortland', `Honeygold', and `Macoun') fractured between cells. `Honeycrisp' had fewer cells/100 cm2 than the other cultivars. After 9 months of storage, breaking force, cell size, and K+/Ca2+ decreased, while cell number/100 cm2, Ca2+ content, and K+ content increased for all cultivars. Cell number/100 cm2 was significantly less and breaking force was significantly greater for tissue from CA than air-stored fruit.
Developing new cherry cultivars requires breeders to be aware of existing and emerging needs throughout the supply chain, from producer to consumer. Because breeding programs in perennial crop plants like sweet and tart cherries require both extended time and extensive resources, understanding and targeting priority traits is critical to improve the efficiency of breeding programs. This study investigated the relative importance of fruit and tree traits to sweet and tart cherry producers using ordered probit models. Tart cherry producers considered productivity and fruit firmness to be the most important traits, whereas sweet cherry producers regarded fruit size, fruit flavor, fruit firmness, freedom from pitting, and powdery mildew resistance as important traits. The location of producers’ orchards and their demographic backgrounds influenced their perceptions of the importance of traits. Our findings provide a quantitative basis to reinforce existing priorities of breeding programs or suggest new targets.
The germplasm base of strawberries is restricted. The major cultivated strawberry species, Fragaria ×ananassa, originated ≈250 years ago when South American F. chiloensis subsp. chiloensis forma chiloensis and North American F. virginiana subsp. virginiana accidentally hybridized in European gardens. Since that time, only a handful of native clones have been used by breeders. As a novel way to expand the germplasm base of the strawberry, we preselected native clones of F. virginiana and F. chiloensis for a wide range of horticulturally important characteristics and then reconstructed F. ×ananassa by crossing superior clones of each. Before crossing between species, we undertook one round of selection within species to maximize diversity. Reconstruction appeared to be an effective method of strawberry improvement, because superior families and individuals were identified that had outstanding vigor, high productivity, seed set, fruit color, and firmness. None of the fruit were of commercial size, but one reconstruction family, FVC 11 [(F. virginiana Frederick 9 × LH 50-4) × (F. chiloensis Scotts Creek × 2 MAR 1A)], had individuals with fruit weights of almost 20 g.
Establishing marker-locus-trait associations to enable marker-assisted breeding depends on having an extensive, reliable database for phenotypic traits of interest in relevant germplasm. A reference germplasm set of 467 apple (Malus ×domestica Borkh.) cultivars, selections, and seedlings (referred to as individuals) was identified as part of the USDA-Specialty Crop Research Initiative (SCRI) project, RosBREED. The germplasm set provides efficient allelic representation of current parents in RosBREED demonstration apple breeding programs at Cornell University, Washington State University, and the University of Minnesota. Phenotyping at the three locations was conducted according to standardized protocols, focusing on fruit traits evaluated at harvest and after 10 and 20 weeks of refrigerated storage. Phenotypic data were collected for the sensory texture traits of firmness, crispness, and juiciness as well as for instrumental texture measures. In 2010 and 2011, fruit from 216 and 330 individuals, respectively, were harvested and a total of 369 individuals were evaluated over the two years. Correlations between sensory and instrumental texture measures were high in some instances. Moderate year-to-year repeatability of trait values was observed. Because each location had a largely unique set of individuals, as well as differing environmental conditions, means, ranges, and phenotypic variances differed greatly among locations for some traits. Loss of firmness and crispness during storage was more readily detected instrumentally than by the sensory evaluation.
Consumer preferences for attributes of fresh peach fruit in the United States are largely unknown on a national basis. We used a choice experiment to explore market segmentation based on consumer heterogeneous preference for fruit attributes including external color, blemish, firmness, sweetness, flavor, and price. We collected the data using an online survey with 800 U.S. consumers. Using a latent class logit model, we identified three segments of consumers differing by different sets of preferred quality attributes: experience attribute-oriented consumers, who valued fruit quality (48.8% of the sample); search attribute-oriented consumers, who valued fruit appearance (33.7% of the sample); and balanced consumers, who considered search attributes and experience attributes but who valued each in a balanced way (17.5% of the sample). Each group demonstrated differentiated demographics and purchasing habits. The results have important marketing implications for peach breeders and suppliers.
Dietary antioxidants may have a role in preventing some of the chronic diseases in humans resulting from free radical oxidation of lipids and other cellular components. Blueberries (Vaccinium L. sp.) are considered one of the best fresh fruit sources of antioxidants, and there is the potential to increase the antioxidant activity further through breeding. Thus, the variability of fruit antioxidant activity (AA) was examined among a set of 16 highbush and interspecific hybrid cultivars grown at locations in Minnesota (MN), Michigan (MI), and Oregon (OR) over 2 years (1998 and 1999) to determine effects of genotype, year, and location. Nine cultivars were common to all three locations in both years. Antioxidant activity, total phenolic content (TPH), and total anthocyanin content (ACY), were determined in triplicate samples from each genotype. Cultivars differed significantly (P ≤ 0.05) in AA, TPH, and ACY both within and over locations. The single location mean AA for all cultivars changed significantly between the 2 years in OR and in MI, while the single location mean for TPH differed between the 2 years in MN and MI. Changes in cultivar rank were significant for AA, TPH, and ACY between years within each location. Significant changes in rank for TPH and ACY were also noted between pairs of locations as well. Pearson's correlation for AA (based on cultivar means) appeared highest between MN and OR (r = 0.90) and MN and MI (r = 0.69) in 1998; correlations between locations for the combined years were 0.74 for MN and OR, 0.55 for MN and MI and 0.45 for MI and OR. For the group of nine cultivars, AA correlated well with TPH within each location, with r ranging from 0.67 to 0.95 for data from individual and combined years. Correlation of AA with ACY at each location was lower than that for AA with TPH, in both individual and combined years. This study demonstrates significant genotype× environment interaction for AA in blueberry.
MN55 is an apple (Malus ×domestica Borkh.) cultivar recently released by the University of Minnesota apple breeding program, with fruit marketed in the U.S. as Rave®. When stored for 4 months at 0 to 4 °C, MN55 fruit can develop several storage disorders, including skin dimpling. Skin dimpling incidence was greater for fruit harvested 1 week later than those harvested earlier. Dimpling was not alleviated by prestorage treatments of 1-methylcyclopropene or diphenylamine or by holding fruit at room temperature for 1 day before long-term cold storage. However, dimpling incidence was very low when fruit were stored at 6 to 7 °C. Because viruses have been implicated in other fruit dimpling disorders, the presence of viruses in MN55 leaves and fruit was studied. Apple stem pitting virus (ASPV) was detected by microscopy, reverse transcriptase polymerase chain reaction (RT-PCR) methodology, and high throughput sequencing (HTS) in peel of fruit from MN55 trees that exhibited skin dimpling after 4 months of storage at 0 to 1 °C. ASPV was also detected in supermarket-purchased fruit of other cultivars with noticeable skin dimpling. Although ASPV was not conclusively demonstrated to cause skin dimpling in our work, its prevalence indicates that further investigations are warranted to determine the relationship between viruses and skin deformities in stored apples.
Incorporating DNA-informed breeding techniques can improve selection efficiency for desired traits as compared with conventional breeding methods that do not use DNA-informed techniques. Incorporation of DNA technologies requires additional costs associated with reagents, equipment, and labor. To elucidate the cost-effectiveness of DNA-informed breeding in perennial crops with multiple years per generation, we conducted a cost–benefit analysis examining incorporation of marker-assisted selection (MAS), a type of DNA-informed breeding, applied to an apple breeding program. Annual operational costs for a midwest apple breeding program were used to develop a simulation with inputs including itemized costs and per unit costs for procedures at each breeding program stage. Simulations compared costs of MAS breeding techniques to conventional breeding methods to identify the break-even point (BEP) where cost-savings associated with MAS equals the accrued additional costs. Additional sensitivity analyses were conducted to examine changes in laboratory costs, seedling maintenance costs, and seedling evaluation costs. We found the BEP for this program occurs when MAS results in a removal rate of 13.18%, and changes to other costs (i.e., maintenance costs) result in a smaller percent decrease to the overall program budget. Our findings are useful to perennial crop breeding programs in which managers are considering incorporating DNA-informed breeding techniques.