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  • Author or Editor: Rui Hai Liu x
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The New York strawberry (Fragaria ×ananassa) industry is focused on sale of relatively short term storage cultivars that are ripe at harvest. Although storage of harvested fruit at low temperatures is generally recommended, growers have reported reduced fruit quality in the market after low temperature storage. Therefore we have explored the potential for using intermediate temperatures for strawberry storage. Physical qualities and antioxidant composition of the Jewel cultivar stored in 75%, 85%, or 95% RH at 0.5, 10, and 20 °C for 4 days have been studied. Overall quality declined more rapidly at 20 °C, especially at 95% RH, than at 10 °C and 0.5 °C. There was little change in weight loss at 0.5, 10, and 20 °C for 2 days but it increased at the lowest RH at 10 °C and increased rapidly from day 3 at 20 °C in lower RHs. Firmness was maintained, or even increased, at 0.5 or 10 °C than 20 °C, but soluble solids concentrations were lower at higher than lower storage temperatures. Red color development and anthocyanin concentrations were controlled more at 0.5 or 10 °C than at 20 °C. Total phenolic compounds were higher at 20 °C than at other temperatures at all RHs. The total antioxidant capacity of berries was higher at 10 °C than at 0.5 or 20 °C. However, total ascorbic acid concentrations, flavonoid contents, and were not affected by RH and temperature. In conclusion, while the best temperature for long term storage is 0.5 °C, quality can be maintained at 10 °C for acceptable periods of time. High RH environments increase the loss of quality at higher storage temperatures. Higher storage temperatures may cause faster ripening and accumulation of antioxidant compounds, but marketable quality of the fruit may be reduced.

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Cytosine methylation plays important roles in regulating gene expression and modulating agronomic traits. In this study, the fluorescence-labeled methylation-sensitive amplified polymorphism (F-MSAP) technique was used to study variation in cytosine methylation among seven pecan (Carya illinoinensis) cultivars at four developmental stages. In addition, phenotypic variations in the leaves of these seven cultivars were investigated. Using eight primer sets, 22,796 bands and 950 sites were detected in the pecan cultivars at four stages. Variation in cytosine methylation was observed among the pecan cultivars, with total methylation levels ranging from 51.18% to 56.58% and polymorphism rates of 82.29%, 81.73%, 78.64%, and 79.09% being recorded at the four stages. Sufficiently accompanying the polymorphism data, significant differences in phenotypic traits were also observed among the pecan cultivars, suggesting that cytosine methylation may be an important factor underlying phenotypic variation. Hypermethylation was the dominant type of methylation among the four types observed, and full methylation occurred at higher levels than did hemimethylation in the pecan genomes. Cluster analysis and principal coordinate analysis (PCoA) identified Dice coefficients ranging from 0.698 to 0.778, with an average coefficient of 0.735, and the variance contribution rates of the previous three principal coordinates were 19.6%, 19.0%, and 18.2%, respectively. Among the seven pecan cultivars, four groups were clearly classified based on a Dice coefficient of 0.75 and the previous three principal coordinates. Tracing dynamic changes in methylation status across stages revealed that methylation patterns changed at a larger proportion of CCGG sites from the 30% of final fruit-size (30%-FFS) stage to the 70%-FFS stage, with general decreases in the total methylation level, the rate of polymorphism, and specific sites being observed in each cultivar. These results demonstrated that the F-MSAP technique is a powerful tool for quantitatively detecting cytosine methylation in pecan genomes and provide a new perspective for studying many important life processes in pecan.

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Scion wood of ‘Caddo’ and ‘Desirable’ pecan (Carya illinoinensis) was grafted onto the epicotyl of 1-month-old, open-pollinated ‘Shaoxing’ pecan seedlings for evaluation as a grafting technique to reduce the time to produce grafted trees. The results showed that seedlings grafted with “base scions” had higher survival than those grafted with “terminal scions” for both ‘Caddo’ and ‘Desirable’. Also, grafting with paraffinic tape could achieve greater success rate than that with medical tape. The most ideal time to perform this grafting was late April in Nanjing, China, when pecan seedlings were about 35 days old. This study demonstrated that the technique yielded successful epicotyl grafting of >70%, and it could thus be applied in practice.

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