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  • Author or Editor: Wei Wang x
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The effects of preharvest methyl jasmonate (MJ) application on fruit quality, flavonoid content and antioxidant capacity (ORAC) in black raspberry cv. Jewel (Rubus occidentalis L) were studied under field conditions. Raspberries treated with 0.1 mm methyl jasmonate had 20% higher soluble solids content, 20% higher total sugars, 16% higher fructose, 34% higher glucose and 30% lower titratable acids, 31% lower malic acid and 17% lower citric acid than untreated fruit. El-lagic acid, quercetin 3-glucoside, kaempferol 3-glucoside, kaempferol 3-glucuronide, cyanidin 3-glucoside and cyaniding 3-rutinoside were found in raspberry fruit extract. Cyanidin 3-rutinoside was the most dominant anthocyanin and was the major contributor to antioxidant activity in Jewel raspberries. MJ treatments significantly enhanced the content of anthocyanins by 92%, total phenolics by 53%, flavonoids by 98% and the antioxidant capacities by 74% in the fruit. The ORAC value was positively correlated with anthocyanins and total phenolics. In this study, the correlation coefficient for ORAC (y) vs anthocyanins (x) was 0.977 (y = 0.056x + 27.874), and that for ORAC (y) vs. total phenolics (x) was 0.988.

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Chestnut (Castanea mollissima Bl.) is a popular nut in Chinese and International market. However, storage of chestnut is difficult. In this study, the relationships of respiration rate, metabolic pathway, key enzymatic activities, metabolites, and membrane peroxidation with chestnut rotting during storage at room temperature (25 °C) and low temperature (0–3 °C) were investigated. The results show that the respiration rate of chestnut gradually decreases during storage at room temperature. Under the lower temperature, the respiration rate reduced 67.53% within 1 day, then gradually increased. Compared with room temperature, the lower temperature also significantly inhibited glycolysis, maintained higher level of tricarboxylic acid cycling, and reduced the conversion of pyruvate to ethanol and lactate. In addition, chloramphenicol acetyltransferase activities were inhibited while superoxide dismutase activities were high under the lower temperature, which resulted in the reduction of membrane peroxidation. Subsequently, the chestnut rotting rate was significantly reduced. In conclusion, the primary reason for chestnut rotting is the reduction of proper physiologic function and then bacteria and pathogen infection. Chestnut rotting rate during storage can be significantly reduced through an appropriate environment and new techniques and chemicals.

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Salicylic acid (SA) as a plant signal molecule plays an important regulatory role in stimulating the accumulation of plants’ defensive compounds. Numerous studies have shown its regulating effects on the biosynthesis of flavonoids. However, the controlling mechanism needs to be made clear further. Here, Vitis vinifera L. ‘Cabernet Sauvignon’ cell suspension cultures were treated with SA and its synthesis inhibitor paclobutrazol (Pac) to investigate their effects on flavonoid biosynthesis. The accumulation of gene transcripts and proteins of flavonoid biosynthesis pathway enzymes, including chalcone synthase (VvCHS), chalcone isomerase (VvCHI), dihydroflavonol 4-reductase (VvDFR), and anthocyanidin synthase (VvANS), were detected using real-time polymerase chain reaction (RT-PCR), quantitative polymerase chain reaction (qPCR), and western-blotting techniques. The results showed that treatment with exogenous SA at the proper concentration enhanced the production of flavonoids such as anthocyanins and proanthocyanidins (PAs) inside the suspension-cultured cells. The induction of anthocyanins and PAs was found to be time course-dependent. The mRNA and protein accumulation of VvCHS, VvCHI, VvDFR, and VvANS in the treatment system were enhanced too, and the changes were observed concomitantly. Treatment of Pac inhibited the induction of the accumulation of gene transcripts and proteins in accordance with the decreased accumulation of flavonoids. These results suggest that exogenous SA could induce both transcript and protein accumulation of flavonoid biosynthesis-related enzymes and in turn enhance the accumulation of flavonoid compounds such as anthocyanins and PAs in suspension-cultured grape cells.

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Luculia pinceana Hook. (Rubiaceae) is a typical distylous species with dimorphic and long-styled monomorphic populations. Within this study, we developed 13 microsatellite markers from L. pinceana using a modified biotin–streptavidin capture method. Polymorphism of each locus was assessed in 30 individuals from four dimorphic populations and one monomorphic population. The average allele number of these microsatellites was 4.153 per locus ranging from three to seven. The observed and expected heterozygosities were from 0.040 to 0.840 and from 0.571 to 0.769, respectively. Additionally, all 13 identified microsatellite markers were successfully amplified in its related species, L. yunnanensis, 10 of which showed polymorphism. These microsatellite markers could provide a useful tool for further study of the breeding system and the population genetic structure in this species and within other Luculia species.

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Cherry leaf spot (CLS), caused by Passalora circumscissa, is a fungal disease that can cause decreased fruit quality and yield via inconsistent ripening or premature defoliation. Germplasm resource screening is the most reliable approach to disease control for economically important crops. However, information is limited in China about the resistance of cherry cultivars to leaf spot caused by P. circumscissa. The aim of this study was to identify the resistance levels of cherry cultivars. Fifty-two cherry cultivars, including 40 Prunus avium, four Prunus pseudocerasus, and eight Prunus cerasus cultivars were collected for resistance level characterization. These specimens were then used to screen for P. circumscissa resistance through both detached leaf assays and natural field infection. Significant differences in the disease index (DI) value among test cultivars, ranging from 5.7 (resistant) to 53.7 (highly susceptible) and 6.5 (resistant) to 53.2 (highly susceptible), were observed under the controlled and field conditions respectively. Correlation coefficients between DI in pairs of years were highly significant (0.77–0.86). Although resistance rankings for cherry cultivars between screening methods were variable, the resistance levels of 52 cultivars evaluated under controlled and field condition were comparable with a correlation coefficient of 0.70 (P < 0.01). The results indicated that, across cherry cultivars, responses to CLS in the detached leaf assay corresponded well to responses under field conditions. A detached leaf assay was developed as a complementary method to facilitate the screening of cherry cultivars for resistance to leaf spot caused by P. circumscissa. Our study provides a theoretical basis for cherry disease resistance breeding and rational cultivar utilization.

Open Access

Potassium (K) is a critical plant nutrient that determines quality in a myriad of crops and increases production yields. However, excessive application of various types of K fertilizers can decrease both the food quality and yields, which translates as economic losses and food safety issues. The objectives of this study were to 1) elucidate the impacts of different application rates of various K fertilizers on garlic, with the aim to identify the optimal and most economical K fertilizer dosage and 2) compare the effects of applying two common K fertilizers (KCl and K2SO4) on garlic, to determine the optimal combination. From 2018 to 2020, we utilized two distinct K-fertilized fields to conduct our experiments. The results revealed optimal KCl fertilization increased the biomass and vegetation index in garlic, and promoted the transfer of nitrogen, phosphorus, and potassium nutrients from the stem and leaf to bulb, thereby increasing bulb production. The application of KCl fertilizer increased the number of cloves, the diameters of the cloves and bulbs, and reduced variations in bulb size. In addition, the application of KCl fertilizer improved the nutritional quality (Vitamin C, soluble sugar, soluble protein, and allicin) of the garlic and reduced the accumulation of nitrate. However, excessive KCl fertilizer cause decreased yields, appearance traits, and nutritional quality. Applying the same rate of K fertilizer in the form of K2SO4 in isolation increased the garlic yield by only 0.1% to 22.5% when compared with KCl fertilizer. However, the results were not always significant. In this study, the highest yields, appearance traits, and nutritional quality were achieved with the ratio of K2SO4: KCl = 3:1. Consequently, to ensure the highest economic value (considering the market prices of K fertilizer, garlic sprouts, and bulbs), the authors recommend a K fertilizer rate of 252.5 kg·ha−1 K2O, with K2SO4 accounting for 61.6% for garlic production in field.

Open Access

To describe the influence of different pecan seedling rootstocks on drought stress resistance, 12 rootstocks of ‘87MX1-2.2’, ‘87MX5-1.7’, ‘Elliott’, ‘Frutoso’, ‘Giles’, ‘Major’, ‘Moore’, ‘Peruque’, ‘Posey’, ‘Riverside’, ‘San Felipe’, and ‘VC1-68’ were selected as rootstock treatments for grafting. In addition, the experimental materials for the grafted young ‘Pawnee’ tree treatments included the pressure-volume technique (PV technique) and cutting shoot transpiration methods to plot the PV and the cutting shoot transpiration curves, and the parameters calculated from the two curves were used to analyze the data produced by the subordinate function and cluster dendrogram methods. The results revealed that the different seedling rootstock treatments influenced the ‘Pawnee’ grafted trees to varying degrees on aspects of drought resistance, the ability to save water, the modulation of osmosis, and the sensitivity of the stomatal response. The order of drought tolerance for these different pecan seedling rootstock treatments from high to low was as follows: ‘Posey’, ‘Peruque’, ‘Riverside’, ‘87MX5-1.7’, ‘VC1-68’, ‘Elliott’, ‘87MX1-2.2’, ‘San Felipe’, ‘Moore’, ‘Major’, ‘Giles’, and ‘Frutoso’.

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A cytoplasmic male sterility (CMS) system is one of the most efficient ways to produce F1 hybrid seeds in pepper (Capsicum annuum). Restorer-of-fertility (Rf) genes are a critical component within the CMS/Rf system. The inheritance of Rf genes in pepper by joint segregation analysis was examined. The inheritance of Rf genes in the two progenies was controlled by two major additive-dominant epistatic genes and additive-dominant epistasis polygene. The two major genes had high additive effects and dominant effects. In addition, there existed significant epistatic effects between the two major genes. The major genes had high heritability in F2, BC1, and BC2 generations. Also, the fertility restorer characteristic can be selected during early generations of the breeding cycle.

Open Access

The purpose of this study was to evaluate physiological, biochemical and molecular changes which occur in unrooted Pelargonium ×hortorum cuttings during storage. Pelargonium cuttings of `Sincerity' (good shipper), `Wendy Ann' (moderate shipper), and `Snowmass' (poor shipper) were stored at 25°C and evaluated over a 5-day period. Following removal from storage, cuttings exhibited progressive declines in photosynthesis, respiration, carbohydrate, starch and protein over time which was significant in all three cultivars, however there was little difference among the cultivars. Ethylene levels produced by `Sincerity' and `Wendy Ann' began to increase 3 days following the initiation of storage, whereas `Snowmass' showed an increase after one day reaching a peak at 3 days and was followed by a sharp decline. When unrooted cuttings of `Snowmass' were stored for a 5-day period at temperatures from 4 to 25°C, it was observed that those stored at 4°C had a significantly higher visual rating, chlorophyll content, root and shoot weight than at higher temperatures tested. The decline in quality progressively became greater from 10 to 25°C. Changes in gene expression of two ACC synthases and an ACC oxidase were evaluated in `Snowmass' cuttings which were stored at 4 and 25°C. Correlations between ethylene and ACC levels with gene expression were observed.

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To find the characteristics of somatic embryogenesis of orchids and elucidate the mechanism, we had previously established an efficient plant regeneration system via somatic embryogenesis in Dendrobium candidum Wall ex Lindl. In this study, a detailed cytological investigation was carried out on the initiation and developmental process of somatic embryogenesis. Based on our observations, the somatic embryogenesis in D. candidum originated from the transition of an embryonic callus cell to the initial somatic embryo cell, and the somatic embryos initiated from those cells. During the transition process, condensation and devacuolation successively occurred in the cytoplasm of the embryonic callus cells, giving rise to the formation of a typical initial somatic embryo cell with dense cytoplasm and a clear nucleus. One of the two pathways in somatic embryogenesis is the single-cell-derived somatic embryo which is generated from an inner initial somatic embryo cell in embryonic callus and develops into a globular somatic embryo in a way similar to zygotic embryogenesis and then keeps developing into a protocorm-like body (PLB). The other is a multiple-cell-derived somatic embryo which is generated from peripheral grouped initial somatic cells in embryonic calli and directly forms globular embryo or multicellular somatic proembryo, lacking the typical early stages of embryogenesis. Both pathways were observed in the somatic embryogenesis system, indicating that the culture system in D. candidum can be a useful tool for investigating the mechanisms underlying orchid embryogenesis.

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