Affect Fruit Quality Research Articles

Evaluation of the Storage Performance of ‘Valencia’ Oranges and Generation of Shelf-Life Prediction Models

We conducted a large-scale, high-throughput phenotyping analysis of the effects of various preharvest and postharvest features on the quality of ‘Valencia’ oranges in order to develop shelf-life prediction models. Altogether, we evaluated 10,800 oranges (~3.6 tons) harvested from three orchards at different periods and conducted 151,200 measurements of 14 quality parameters. The storage time was the most important feature affecting fruit quality, followed by the yield, storage temperature, humidity, and harvest time. The storage time and temperature features significantly affected (p < 0.001) all or most of the tested quality parameters, whereas the harvest time, yield, and humidity conditions significantly affected several particular quality parameters, and the selection of rootstocks had no significant effect at all. Five regression models were evaluated for their ability to predict fruit quality based on preharvest and postharvest features. Non-linear Support Vector Regression (SVR) combined with a data-balancing approach was found to be the most effective approach. It allowed the prediction of fruit-acceptance scores among the full data set, with a root mean square error (RMSE) of 0.195 and an R2 of 0.884. The obtained data and models should assist in determining the potential storage times of different batches of fruit.

Adding Far-Red to Red, Blue Supplemental Light-Emitting Diode Interlighting Improved Sweet Pepper Yield but Attenuated Carotenoid Content.

Supplemental interlighting is commonly used in modern greenhouses to improve light deficiency, but the light spectrum affects fruit quality and color change. This study aimed to analyze the effect of interlighting with red, blue, and additional far-red light on the fruit qualities and carotenoid contents of red and yellow sweet peppers (Capsicum annuum L.). Three light treatments were applied: natural light (NL), NL with red + blue LED interlighting (71 μmol m–2 s–1) (RB), and RB with far-red light (55 μmol m–2 s–1) (RBFR). Ascorbic acid, free sugars, and individual carotenoid content were quantified with HPLC analysis. Fruits were sampled on 2020.11.14 (Group 1) and 2021.01.03 (Group 2) from the plants grown under average light intensities of 335.9 and 105.6 μmol m–2 s–1, respectively. In the overall period, total yields in RB and RBFR were 22 and 33% higher than those in NL in red fruits and 2 and 21% higher in yellow fruits, respectively. In both colored fruits, ascorbic acid, total soluble sugar, and carotenoid content were higher in RB and RBFR than NL. In Group 1, ascorbic acid and total soluble sugar were significantly different between RB and RBFR only in red fruits. In Group 2, ascorbic acids in red and yellow fruits were 9 and 3% higher in RBFR than RB but total soluble sugars were 4 and 2% lower, respectively. Carotenoid contents in red and yellow fruits were 3.0- and 2.1-fold higher in RB and 2.0- and 1.4-fold higher in RBFR than those in NL, respectively. In this study, interlighting had a significant impact on fruit quality in Group 2, mainly due to the increase in the ratio of interlighting to total light by seasonal changes. In particular, red and yellow fruit yields were 9% and 19% higher in RBFR than RB, but carotenoid contents were 26 to 9% lower, respectively. This result exhibited that additional far-red lighting has a trade-off relationship between fruit yield and carotenoid content. Thus, it is necessary to provide an adequate light spectrum according to a specific cultivation purpose, such as improving yield or accumulating plastids in fruits.

Physiological and biochemical mechanisms of fruit cracking: A review

Fruit cracking is a serious physiological disorder that affects fruit quality and productivity. It is a pre-harvest disorder that results in poor quality of fruits; these are not marketable and cause economic losses to growers. Generally, fruit cracking occurs during the second phase of fruit growth when expanding pulp induces pressure to peel and peel becomes thinner and microcracks appear, ultimately fruit splits and drops off from tree. Several factors that contribute to fruit cracking are irregular water supply, heavy crop load, warm-humid climatic conditions, nutrient mis-management and hormonal imbalance. Cultivars having thinner peels and deficiency of Ca, K, B and P in soils are more prone to fruit cracking. This review provides the physiological and biochemical basis of fruit cracking along with recommended control measures to reduce this disorder. Foliar application of synthetic auxins, gibberellins and minerals (Ca, Zn, P and B) at different time intervals for different species to significantly reduce fruit cracking is included in this review. Further molecular studies need to be proposed to study the actual mechanism of cracking through function of genesand biotechnological approaches can be followed so that cracking resistant varieties are produced

Knock-Out of CmNAC-NOR Affects Melon Climacteric Fruit Ripening.

Fruit ripening is an important process that affects fruit quality. A QTL in melon, ETHQV6.3, involved in climacteric ripening regulation, has been found to be encoded by CmNAC-NOR, a homologue of the tomato NOR gene. To further investigate CmNAC-NOR function, we obtained two CRISPR/Cas9-mediated mutants (nor-3 and nor-1) in the climacteric Védrantais background. nor-3, containing a 3-bp deletion altering the NAC domain A, resulted in ~8 days delay in ripening without affecting fruit quality. In contrast, the 1-bp deletion in nor-1 resulted in a fully disrupted NAC domain, which completely blocked climacteric ripening. The nor-1 fruits did not produce ethylene, no abscission layer was formed and there was no external color change. Additionally, volatile components were dramatically altered, seeds were not well developed and flesh firmness was also altered. There was a delay in fruit ripening with the nor-1 allele in heterozygosis of ~20 days. Our results provide new information regarding the function of CmNAC-NOR in melon fruit ripening, suggesting that it is a potential target for modulating shelf life in commercial climacteric melon varieties.

Evolution of Volatile Aroma Compounds and Amino Acids in Cabernet Gernischt Grape Berries (Vitis vinifera L.): Comparison of Different Training Systems for Mechanical Soil Burial.

Soil burial is a survival strategy for grapevines that can safely overwinter in north-western regions of China. A suitable training system was beneficial for soil burial to provide winter protection. Moreover, the training system can also significantly affect fruit quality during the development of grape berries, such as primary and secondary metabolites. In this study, four-year-old Cabernet Gernischt grapevines were used as experimental material and exposed to four training systems, including the Ningxia traditional vertical trunk (control, CK); the gobelet (T1); single guyot (T2); slant trunk with vertical shoot positioning (STVSP) (T3). The results showed that total soluble solid total phenol content was 12.69%, 57% higher under T3 training systems than in the control, and T3 alleviated the canopy density, leading to improving the leaf photosynthetic efficiency gas chromatography-mass spectrometry (GC-MS) assay used to detect the aroma compounds. The results indicated that the T3 training system enhanced the accumulation of alcohols, carbonyl compounds, C6/C9 and esters, which account for the largest proportion of volatile compounds, and the qRT-PCR reveals that VvEcar, Vvter, VvCCD1, and VvLis were raised under T3 at the transcriptional level. Moreover, T3 contributes to most free amino acid synthesis. Additionally, the PCA reveals the correlation of free amino acids under four training systems, which reflected the mostly amino acid related to T3, and thus, we could speculate that T3 enhances the overall aroma. These results may lead to new strategies to select a new, short trunk training system to achieve mechanized buried soil, to prevent cold and produce high-quality wine in this area.

Application of Infrared Imaging for Early Detection of Downy Mildew (Plasmopara viticola) in Grapevine

Late detection of fungal infection is the main cause of inadequate disease control, affecting fruit quality and reducing yield of grapevine. Therefore, infrared imagery as a remote sensing technique was investigated in this study as a potential tool for early disease detection. Experiments were conducted under field conditions, and the effects of temporal and spatial variability in the leaf temperature of grapevine infected by Plasmopara viticola were studied. Evidence of the grapevine’s thermal response is a 3.2 °C increase in leaf temperature that occurred long before visible symptoms appeared. In our study, a correlation of R2 = 0.76 at high significance level (p ≤ 0.001) was found between disease severity and MTD. Since the pathogen attack alters plant metabolic activities and stomatal conductance, the sensitivity of leaf temperature to leaf transpiration is high and can be used to monitor irregularities in temperature at an early stage of pathogen development.

Abscisic acid preharvest application alleviates chilling injury in oranges during cold storage

ABSTRACT Orange fruit are sensitive to develop chilling injury (CI) during postharvest storage. Symptoms are brown depressed areas in the flavedo that coalesce with time causing severe economic losses. Abscisic acid (ABA) is applied during preharvest in different crops to promote cold tolerance but its effect in citrus fruit remains unknown. The objective of this work was to study the effect of preharvest application of ABA in alleviating CI during cold storage (1.0 ± 0.5°C). ABA at 500 mg.L−1 was applied at three different maturity stages of ‘W. Navel’, ‘Valencia’ and ‘Salustiana’ oranges. ABA reduced incidence and severity of CI in the three orange cultivars. This positive effect was cultivar-dependent, being more pronounced in ‘W. Navel’ and ‘Valencia’ compared to ‘Salustiana’. ‘Salustiana’ presented the highest CI incidence (>80% of the fruit with symptoms after 9 weeks of storage) and ABA applications only delayed its appearance. CI incidence was reduced up to 61% in ‘W. Navel’ and 74% in ‘Valencia’ compared to untreated fruit, concomitantly to severity. Evaluation of fruit quality revealed that ABA application does not affect fruit colour firmness or maturity index. Preharvest applications of ABA in oranges alleviate CI during postharvest cold storage without affecting fruit quality.

The Methyltransferase HemK Regulates the Virulence and Nutrient Utilization of the Phytopathogenic Bacterium Xanthomonas citri Subsp. citri.

Citrus canker, caused by the bacterium Xanthomonas citri subsp. citri (Xcc), seriously affects fruit quality and yield, leading to significant economic losses around the world. Understanding the mechanism of Xcc virulence is important for the effective control of Xcc infection. In this report, we investigate the role of a protein named HemK in the regulation of the virulence traits of Xcc. The hemK gene was deleted in the Xcc jx-6 background, and the ΔhemK mutant phenotypically displayed significantly decreased motility, biofilm formation, extracellular enzymes, and polysaccharides production, as well as increased sensitivity to oxidative stress and high temperatures. In accordance with the role of HemK in the regulation of a variety of virulence-associated phenotypes, the deletion of hemK resulted in reduced virulence on citrus plants as well as a compromised hypersensitive response on a non-host plant, Nicotiana benthamiana. These results indicated that HemK is required for the virulence of Xcc. To characterize the regulatory effect of hemK deletion on gene expression, RNA sequencing analysis was conducted using the wild-type Xcc jx-6 strain and its isogenic ΔhemK mutant strain, grown in XVM2 medium. Comparative transcriptome analysis of these two strains revealed that hemK deletion specifically changed the expression of several virulence-related genes associated with the bacterial secretion system, chemotaxis, and quorum sensing, and the expression of various genes related to nutrient utilization including amino acid metabolism, carbohydrate metabolism, and energy metabolism. In conclusion, our results indicate that HemK plays an essential role in virulence, the regulation of virulence factor synthesis, and the nutrient utilization of Xcc.

Metabolite profile of African horned cucumber (Cucumis metuliferus E. May. Ex Naudin) fruit grown under differing environmental conditions

Plant metabolites are known as biological compounds that are essential to the growth and development of a plant and have a direct impact on yield and biochemical constituents of plants. For this study, the objective was to conduct primary metabolomics analysis using liquid chromatography mass spectrometry. African horned cucumber fruits were harvested from plants grown under pots experiment (greenhouse, shade net and open field), soil types (loamy soil and sandy loam) and three water stress levels (no water stress-100%—3L, moderate water stress-75%—2L, and severe water stress-35%—1L) during 2017/18 and 2018/19 seasons. Results showed that the treatment of no water stress combined with sandy loam under shade net environment, significantly increased asparagine content from 10 × 106 to 80 × 106 peak intensity. The treatment of no water stress, in combination with sandy loam soil under open field environment increased 4-hydroxyproline from 10 × 106 to 90 × 106 peak intensity compared to other treatments. It can be deduced that the treatment combination of (no water stress and moderate water stress) and all soil types, under greenhouse environment increased most metabolites content of the fruit when compared to other treatments. Therefore, it subsequently has potential to affect fruit quality such as taste and other biochemical constituents.

Application of a Biostimulant (Pepton) Based in Enzymatic Hydrolyzed Animal Protein Combined With Low Nitrogen Priming Boosts Fruit Production Without Negatively Affecting Quality in Greenhouse-Grown Tomatoes.

Improved nutrient use efficiency together with the use of biostimulants have been little explored thus far to improve fruit yield and quality in economically relevant crops. The aim of this study was to determine the additive or synergistic effects, if any, of the application of an enzyme hydrolyzed animal protein biostimulant (Pepton) combined with priming with low nitrogen (N) in the production and quality of greenhouse tomatoes. Biostimulant treatment (Pepton at a dose equivalent of 4 kg/ha) was applied by ferti-irrigation for 2 months during the vegetative phase both in controls (watered with nutrient solution) and nutrient efficient crop (NEC), in which plants were primed with low N by exposing them to a 30% N deficiency for 2 months, and then recovered for 1 month before fruit production. Foliar water and N contents, pigments, maximum PSII efficiency (Fv/Fm ratio), and phytohormones [including abscisic acid (ABA), salicylic acid (SA), jasmonic acid (JA), and cytokinins] were measured prior and at 4 and 8 weeks after the first application. Fruit production and quality [as indicated by total soluble sugars (TSS) and acidity (TA), and the contents of lycopene, vitamin E, and vitamin C] were measured 1 month later at harvest. Priming with low N availability (NEC plants) doubled (p < 0.001) fruit production (due to an increase in the number of fruits), tended to increase (p = 0.057) by 20% the amount of TSS and increased (p < 0.05) the contents of lycopene (by 90%) and vitamin E (by 40%). Pepton displayed a tendency, almost significant, to improve (p = 0.054) total fruit production both in control and NEC plants, thus showing an additive effect to low N priming in boosting fruit production. Pepton maintained fruit quality in terms of sugar accumulation, total acidity and the contents of carotenoids, vitamins C and E. Pepton-related improvement in fruit production seemed to be related, at least partially, to an increased accumulation of cytokinins and photosynthetic pigments in leaves, which might favor vegetative vigor and ultimately fruit yield. In conclusion, Pepton application was effective in improving the yield of greenhouse tomatoes showing additive effect with low N priming, without negatively affecting fruit quality.

Extract from the Macroalgae Ulva rigida Induces Table Grapes Resistance to Botrytis cinerea.

Fungal pathogens are a central cause of the high wastage rates of harvested fruit and vegetables. Seaweeds from the genus Ulva are fast-growing edible green macroalgae whose species can be found on the shore of every continent, and therefore present a resource that can be utilized on a global scale. In this study, we found that the application of ulvan extract, a sulfated polysaccharide extracted from Ulva rigida (1000 mg/L), elicited table grapes defense and reduced the incidence and decay area of Botrytis cinerea by 43% and 41%, respectively. In addition, compared to the control group at two days post-treatment, ulvan extract elicited a variety of defense-related biomarkers such as a 43% increase in the activity of reactive oxygen species, 4-fold increase in the activity of catalase, 2-fold increase in the activity of superoxide dismutase and 1.4-fold increase in the activity of chitinase. No increase was observed in phenylalanine ammonia-lyase activity, and the treatment did not affect fruit quality parameters such as the pH levels, sugar levels, and titratable acidity of grapes. These results illustrate the potential of ulvan extract to naturally induce the plant defense response and to reduce postharvest decay.

Effects of scion-rootstock interaction on citrus fruit quality related to differentially expressed small RNAs

Rootstock affects the performance of the scion on productivity and fruit quality. Scions on trifoliate orange rootstock could produce better quality of fruits than on other commonly used rootstocks. This phenomenon has been well documented, but genetic factors affecting the fruit quality through interaction of scion and rootstock remained unclear. Fruits in different developmental stages from the Daya mandarin grafted on two genetically divergent rootstocks (Trifoliate orange (Poncirus trifoliata) (Z) and Hongju (Citrus reticulata) (H)) were used for fruit quality, expression of small RNA, and degradome sequencing analysis. Total soluble solids (TSS) of fruit on Z rootstock were significantly higher than those of on H. In contrast, titratable acid (TA) of fruit were lower on Z rootstock. One hundred and eight known and 145 novel microRNAs (miRNA), as well as 555 target genes were identified by in silico analysis and degradome sequencing. One hundred and twenty-nine differentially expressed miRNAs (DEMs) were identified by comparison of miRNA expression between the Daya mandarins grafted on two rootstocks in three different developmental stages. Correlation analysis with the fruits from three navel orange cultivars on two rootstocks showed that four DEMs (Cre-miR159-3p, Cre-miR160a, Cre-miR171b and Cre-miR399-3p) were significant correlated to TSS or TA in some of scion/rootstock combinations. Expressions of Cre-miR399-3p and its target gene INVE demonstrated consistent correlations with fruit quality of four scion varieties grated on Z rootstock, indicating that Cre-miR399–3p and its target gene INVE may be one of the key factors affecting fruit quality in Poncirus trifoliata rootstock.

Pollen Application Methods Affecting Fruit Quality and Seed Formation in Artificial Pollination of Yellow-Fleshed Kiwifruit

This study investigated pollen application methods for artificial pollination in tetraploid kiwifruit cultivars ‘Halla Gold’ and ‘Sweet Gold’ grown in a nonheated plastic-film house in Jeju, Korea. Pollen of the hexaploid cultivar ‘Bohwa’ (A. chinensis var. deliciosa) bred in Korea was used for artificial pollination. We examined the effect of repeated pollination, pretreatment of stigma with wetting materials, application of dry pollen or pollen in suspension on fruit quality, and seed formation. With repeated pollination, pollen tubes in the pistil reached and penetrated the ovule three days after artificial pollination, although the pattern varied depending on the number of dry pollen applications. In both cultivars, the number of pollen tubes was clearly higher following repeated pollination than following single pollination, and fruit weight, dry matter (DM), number of seeds, and 100-seed weight were also higher. When pistillate flowers were pollinated with dry pollen immediately after water sprinkle, both cultivars showed the lowest fruit weight, DM, firmness, number of seeds, and 100-seed weight, whereas there were no significant differences in fruit quality or seed formation for dry pollen application 1 h after water sprinkle, or immediately or 1 h after suspension medium sprinkle. For pollination using a pollen suspension, the fruit weight was lower in both cultivars. There were no significant differences in fruit quality and seed formation following application of dry pollen or a pollen suspension, except for fruit weight in ‘Sweet Gold’. It could be seen from the results of this study that raindrops or dewdrops on the stigma might reduce the efficiency of artificial pollination using dry pollen. Still, the application of repeated pollination enhanced the efficiency of artificial pollination.

Modulating climacteric intensity in melon through QTL stacking.

Fruit ripening is one of the main processes affecting fruit quality and shelf life. In melon there are both climacteric and non-climacteric genotypes, making it a suitable species to study fruit ripening. In the current study, in order to fine tune ripening, we have pyramided three climacteric QTLs in the non-climacteric genotype “Piel de Sapo”: ETHQB3.5, ETHQV6.3 and ETHQV8.1. The results showed that the three QTLs interact epistatically, affecting ethylene production and ripening-related traits such as aroma profile. Each individual QTL has a specific role in the ethylene production profile. ETHQB3.5 accelerates the ethylene peak, ETHQV6.3 advances the ethylene production and ETHQV8.1 enhances the effect of the other two QTLs. Regarding aroma, the three QTLs independently activated the production of esters changing the aroma profile of the fruits, with no significant effects in fruit firmness, soluble solid content and fruit size. Understanding the interaction and the effect of different ripening QTLs offers a powerful knowledge for candidate gene identification as well as for melon breeding programs, where fruit ripening is one of the main objectives.

Harvest maturity highly affects fruit quality attributes of ethylene-treated ‘autumn sense’ hardy kiwifruit

Optimal harvest date is an important quality parameter for hardy kiwifruit. We, therefore, examined the ideal harvest date to obtain high-quality ripe “Autumn sense” hardy kiwifruit. The fruit was harvested at four different harvest maturity stages [6.2%, 7.1%, 8.1%, and 9.1% average soluble solids content (SSC); H1, H2, H3, and H4, respectively], then treated with exogenous ethylene at ambient temperature, to examine the quality of the ripening fruit. The four harvest maturity stages differed significantly in firmness, SSC, titratable acidity (TA), and SSC/TA ratio, both in freshly harvested and ripe hardy kiwifruit (p < 0.001). Fruit firmness at harvest gradually decreased from 32.1 to 25.1 N, while SSC increased steadily as harvest maturity increased. TA increased steadily from 0.8 in H1 to 1.1% in H3, and was lower in H4. After ethylene treatment, the range of firmness was much lower, at 2.7–3.1 N, while SSC increased significantly from 15.1% in H1 to 16.4% in H4. TA decreased significantly from 1.0% at harvest to 0.7% after ethylene treatment, regardless of harvest maturity stage. For H3 fruit, TA was 56% lower after ethylene treatment than before treatment. After treatment, H3 had the highest SSC/TA (p < 0.001). Consumer preference was higher for H3 and H4 than H1 and H2, and was highly correlated with the SSC/TA ratio at harvest and after ethylene treatment, and with SSC at harvest. These results suggest that TA, SSC, and SSC/TA should be considered for determining the optimal harvest maturity for hardy kiwifruit. This study reveals that the quality of ripened hardy kiwifruit can be maximized by controlling harvest maturity.

Late summer pruning improves the quality and increases the content of functional compounds in Fuji apples

The objective of this paper was to evaluate the effect of the time of summer pruning on the quality of Fuji apples, on the red color and functional properties, at harvest and after 3.5 months of cold storage. The treatments evaluated consisted of the control (without summer pruning) and summer pruning in December, January, and February. The percentage of fruit with more than 50% red color on the skin was 20.5% higher when summer pruning was performed later than when performed early. In general, summer pruning in January and February provided fruit with a relatively high content of anthocyanins (19 and 25.1 mg cyaniding 3-glycoside·100 g-1 FW, respectively), relatively high values of total phenolic compounds (370.1 and 438.7 mg EAG·100 g-1 FW, respectively) and total antioxidant activity by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) method (8,097.5 and 8,089.2 µMol Trolox·100 g-1 FW, respectively) in the 2017/18 season. Summer pruning did not affect fruit quality after cold storage. Summer pruning performed in January or February increased functional compounds content and improved red color, while in February it increased flesh firmness.

Utilizing spectral vegetation indices for yield assessment of tomato genotypes grown in arid conditions

Tomato is among important vegetable crops cultivated in different climates; however, heat stress can greatly affect fruit quality and overall yield. Crop reflectance measurements based on ground reflectance sensor data are reliable indicators of crop tolerance to abiotic stresses. Here, we report on using non-destructive spectral vegetation indices to monitor yield traits of 10 tomato genotypes transplanted on three different dates (Aug. 2, Sept. 3 and Oct. 1) during 2019 growing season in the Riyadh region. The ten genotypes comprised six commercial cultivars–(Pearson Improved, Strain B, Valentine, Marmande VF, Super Strain B, and Pearson early) ––and four local Saudi cultivars (Al-Ahsa, Al-Qatif, Hail and Najran). Spectral reflectance data were utilized using a FieldSpec 3 spectroradiometer in the range of 350–2500 nm to calculate nine vegetation indices (VIs): Normalized Water Band Index (NWBI), Difference Water Index (NDWI), Photochemical Reflectance Index (PRI), Normalized Difference Vegetation Index (NDVI), Green Normalized Difference Vegetation Index (GNDVI), Red Edge Normalized Difference Vegetation Index, Soil Adjusted Vegetation Index (SAVI), Red Edge Normalized Difference Vegetation Index (RENDVI), Renormalized Difference Vegetation Index (RDVI), and Normalized Difference Nitrogen Index (NDNI). VIs and yield parameters (total fruit yield, harvest index) revealed that second transplanting date was optimal for all the genotypes. Valentine showed the best growth performance followed by Najran, Hail, Super Strain B and finally Pearson early. For all the three transplanting dates, Valentine recorded the highest total fruit yield. Additionally, some genotypes had no significant differences in the VIs values or the total fruit yield between the second and third transplanting dates. This study indicated that yield parameters could be linked to rapid, non-destructive hyperspectral reflectance data to predict tomato production under heat stress.

VvMYB15 and VvWRKY40 Positively Co-regulated Anthocyanin Biosynthesis in Grape Berries in Response to Root Restriction.

In most grapevine planting regions, especially in south of China, plenty of rainfall and high water level underground are the characteristic of the area, a series of problem during fruit ripening easily caused poor color quality. Thereby affecting fruit quality, yield and economic benefits. The accumulation of anthocyanin is regulated by transcriptional regulatory factor and a series of cultivation measures, root restriction can make plants in the environment of stress and stress relief, root restriction induced the higher expression of VvMYB15 and VvWRKY40, and consistent with anthocyanin accumulation. Whether and how root restriction-inducible VvMYB15 and VvWRKY40 transcription factor regulate anthocyanin synthesis in grape berry is still unclear. In this study, we identified that the transient overexpression of VvMYB15 and VvWRKY40 alone or both in strawberry fruits and grape berries can promote anthocyanin accumulation and increase the expression level of anthocyanin biosynthetic genes, indicating VvMYB15 and VvWRKY40 play a positive regulator of anthocyanin biosynthesis. Furthermore, we confirmed that both VvMYB15 and VvWRKY40 specifically bind to the promoter region of VvF3′5′H and VvUFGT, and the expression of VvF3′5′H and VvUFGT is further activated through the heterodimer formation between VvMYB15 and VvWRKY40. Finally, we confirmed that VvMYB15 promoted anthocyanin accumulation by interacting with VvWRKY40 in grape berries, our findings provide insights into a mechanism involving the synergistic regulation of root restriction-dependent coloration and biosynthesis via a VvMYB15 and VvWRKY40 alone or both in grape berries.

Glucose sensor MdHXK1 activates an immune response to the fungal pathogen Botryosphaeria dothidea in apple.

Sugars are essential regulatory molecules involved in plant growth and development and defense response. Although the relationship between sugars and disease resistance has been widely discussed, the underlying molecular mechanisms remain unexplored. Ring rot caused by Botryosphaeria dothidea (B. dothidea), which severely affects fruit quality and yield, is a destructive disease of apples (Malus domestica Borkh.). The present study found that the degree of disease resistance in apple fruit was closely related to glucose content. Therefore, the gene encoding a hexokinase, MdHXK1, was isolated from the apple cultivar 'Gala', and characterized during the defense response. Overexpression of MdHXK1 enhanced disease resistance in apple calli, leaves and fruits by increasing the expression levels of genes related to salicylate (SA) synthesis (PHYTOALEXIN DEFICIENT 4, PAD4; PHENYLALANINE AMMONIA-LYASE, PAL; and ENHANCED DISEASE SUSCEPTIBILITY 1, EDS1) and signaling (PR1; PR5; and NONEXPRESSER OF PR GENES 1, NPR1) as well as increasing the superoxide (O2- ) production rate and the hydrogen peroxide (H2 O2 ) content. Overall, the study provides new insights into the MdHXK1-mediated molecular mechanisms by which glucose signaling regulates apple ring rot resistance.

Fruit Quality Attributes of ‘Arisoo’ and ‘Picnic’ Apples as Influenced by 1-Methylcyclopropene Concentration and Its Application Frequency during Cold Storage

The efficacy of 1-methylcyclopropene (1-MCP) in maintenance of apple fruit quality can differ depending on apple cultivar, ethylene content at harvest, 1-MCP concentration, the interval between harvest and 1-MCP application, and the number of applications. In this study, we investigated whether the 1-MCP concentration and its application frequency differently affected fruit quality attributes of the two new apple cultivars ‘Arisoo’ and ‘Picnic’. The fruits were treated with 1-MCP (as single or double treatments) at the rate of 0 μL L−1 (control), 0.5 μL L−1, 1 μL L−1, 0.5 + 0.5 μL L−1, and 1 + 1 μL L−1 for 18 h, and they were stored at 0 °C up to six months. Comparatively, the fruit qualities of 1-MCP treated fruits were higher than that of the control during cold storage, with a higher suppression of internal ethylene content and a slower reduction of titratable acidity in 1-MCP treatments than the controls throughout the cold storage in both cultivars, regardless of the concentration and number of applications. Reduction of fruit firmness and soluble solid contents were maintained by single application of 0.5 μL L−1 1-MCP in ‘Arisoo’ apple, while double application of 0.5 + 0.5 μL L−1 was needed in ‘Picnic’ cultivar. The effective concentration for weight-loss reduction was found to be the single application of 1 μL L−1 1-MCP in both ‘Arisoo’ and ‘Picnic’. Conclusively, 1-MCP as single treatment at the rate of 0.5 μL L−1 could be sufficient in inhibiting ethylene action and maintaining fruit quality losses during cold storage, particularly in ‘Arisoo’. However, double application of 1-MCP might be necessary for some quality attributes in ‘Picnic’ apple.