Postharvest treatment with (−) and (+)-methyl jasmonate stimulates anthocyanin accumulation in grapes

The Preharvest Application of Stress Response Elicitors Improves the Content of Bioactive Compounds without Modifying the Sensory Attributes of Butterhead Lettuce (Lactuca sativa var. capitata)

Using stress elicitors in fruits and vegetables is considered a good strategy to increase the content of bioactive compounds in plant foods. However, bioactive compounds can affect the sensory characteristics of food products, and little is known about their shelf-life stability in fresh produce treated with elicitors. In the present work, carotenoids and polyphenols were quantified by spectrophotometric methods in red and green butterhead lettuce treated with elicitors that had previously been demonstrated to increase bioactive compounds: arachidonic acid (AA), methyl jasmonate (MJ), and Harpin protein (HP). The bioactive compounds were determined immediately and during three weeks after harvest. A descriptive sensory analysis was carried out, which included odor, taste, tactile, and visual attributes of control and elicitor-treated lettuce. Carotenoids showed greater shelf-life stability than polyphenols, and both were more stable in red than in green lettuce during the first two weeks of storage. The best elicitor was MJ, which increased phenolic compounds (red and green lettuce), anthocyanins, and carotenoids (red lettuce) through the storage period. Color intensity, crispness, wettability, and bitter taste were some of the primary sensory attributes in butterhead lettuce and were not affected by any treatment. Other organoleptic properties were also not affected by the elicitors. These results suggest that elicitation could improve the content of bioactive compounds, which is stable through the shelf-life of butterhead lettuce, without any adverse effect on the sensory properties.

The roles of brassinosteroids and methyl jasmonate on postharvest grape by regulating the interaction between VvDWF4 and VvTIFY 5 A

Brassinosteroids (BRs) and methyl jasmonate (MeJA) are known for the regulation of plant development, and the crosstalk between them is important for plant growth. However, the interaction between them in the development of postharvest fruit is unresolved. We found that BR treatment enhanced the accumulation of sugar composition and aroma content, reduced the content of organic acids (such as tartaric acid) and promoted the coloring of grape callus. After the application of MeJA, the acidity increased and the sugar content decreased. The physiological data showed that exogenous BR also attenuated the JA inhibition of postharvest ripening in grape. DWF4 is a key enzyme in the BR biosynthetic pathway, and it can effectively regulate the content of endogenous BRs. TIFY 5 A, which belongs to the Jasmonate ZIM-domain (JAZ) family, can be baited by DWF4 through the Y2H experiment. TIFY 5 A represses the expression of dihydroflavonol-4-reductase (DFR) which plays a key role in the synthesis of anthocyanins, while this will be alleviated by VvDWF4. The interaction between TIFY 5 A and DWF4 contributes to the cross talk between JA and BR signalling pathways. This is also verified by the transgenic experimental results. The results in this paper provides a new insight into the relationship between BR and JA signalling pathways, which is important to the regulation of the postharvest ripening of grape.

Application of Methyl Jasmonate to Papaya Fruit Stored at Lower Temperature Attenuates Chilling Injury and Enhances the Antioxidant System to Maintain Quality

Papaya fruit has a limited shelf life due to its sensitivity to decay and chilling damage during cold storage. The application of methyl jasmonate (MeJA) is known to reduce the incidence of disease and chilling injury, and to maintain the overall quality of the papaya fruit when stored at low temperature. Consequently, the effects of postharvest MeJA (1 mM) immersion on papaya fruits during low-temperature storage (10 °C ± 2 °C) for 28 days were studied. The experiment revealed that MeJA treatment significantly decreased the papaya fruit's weight loss, disease incidence, and chilling injury index. Furthermore, the accumulation of malondialdehyde and hydrogen peroxide was markedly lower after the application of MeJA. In addition, MeJA treatment exhibited significantly higher total phenols, ascorbic acid, antioxidant activity, and titratable acidity in contrast to the control. Similarly, MeJA-treated papaya fruits showed higher antioxidant enzymatic activity (superoxide dismutase, catalase, and peroxidase enzymes) with respect to the control fruits. In addition, MeJA reduced the soluble solids content, ripening index, pH, and sugar contents compared to the control fruits. Furthermore, MeJA-treated papaya fruit exhibited higher sensory and organoleptic quality attributes with respect to untreated papaya fruits. These findings suggested that postharvest MeJA application might be a useful approach for attenuating disease incidence and preventing chilling injury by enhancing antioxidant activities along with enhanced overall quality of papaya fruits during low-temperature storage.

Unraveling the functional characterization of a jasmonate-induced flavonoid biosynthetic CYP45082G24 gene in Carthamus tinctorius

The cytochrome P450 superfamily of monooxygenases plays a major role in the evolution and diversification of plant natural products. The function of cytochrome P450s in physiological adaptability, secondary metabolism, and xenobiotic detoxification has been studied extensively in numerous plant species. However, their underlying regulatory mechanism in safflower still remained unclear. In this study, we aimed to elucidate the functional role of a putative CtCYP82G24-encoding gene in safflower, which suggests crucial insights into the regulation of methyl jasmonate-induced flavonoid accumulation in transgenic plants. The results showed that methyl jasmonate (MeJA) was associated with a progressive upregulation of CtCYP82G24 expression in safflower among other treatment conditions including light, dark, and polyethylene glycol (PEG). In addition, transgenic plants overexpressing CtCYP82G24 demonstrated increased expression level of other key flavonoid biosynthetic genes, such as AtDFR, AtANS, and AtFLS, and higher content of flavonoid and anthocyanin accumulation when compared with wild-type and mutant plants. Under exogenous MeJA treatment, the CtCYP82G24 transgenic overexpressed lines showed a significant spike in flavonoid and anthocyanin content compared with wild-type and mutant plants. Moreover, the virus-induced gene silencing (VIGS) assay of CtCYP82G24 in safflower leaves exhibited decreased flavonoid and anthocyanin accumulation and reduced expression of key flavonoid biosynthetic genes, suggesting a possible coordination between transcriptional regulation of CtCYP82G24 and flavonoid accumulation. Together, our findings confirmed the likely role of CtCYP82G24 during MeJA-induced flavonoid accumulation in safflower.

Safflower Flavonoid 3′5′Hydroxylase Promotes Methyl Jasmonate-induced Anthocyanin Accumulation in Transgenic Plants

Flavonoids are the most abundant class of secondary metabolites that are ubiquitously involved in plant development and resistance to biotic and abiotic stresses. Flavonoid biosynthesis involves multiple channels of orchestrated molecular regulatory factors. Methyl jasmonate (MeJA) has been demonstrated to enhance flavonoid accumulation in numerous plant species; however, the underlying molecular mechanism of MeJA-induced flavonoid biosynthesis in safflower is still not evident. In the present study, we revealed the underlying molecular basis of a putative F3′5′H gene from safflower imparting MeJA-induced flavonoid accumulation in transgenic plants. The constitutive expression of the CtF3′5′H1 gene was validated at different flowering stages, indicating their diverse transcriptional regulation through flower development in safflower. Similarly, the CtF3′5′H1-overexpressed Arabidopsis plants exhibit a higher expression level, with significantly increased anthocyanins and flavonoid content, but less proanthocyanidins than wild-type plants. In addition, transgenic plants treated with exogenous MeJA revealed the up-regulation of CtF3′5′H1 expression over different time points with significantly enhanced anthocyanin and flavonoid content as confirmed by HPLC analysis. Moreover, CtF3′5′H1- overexpressed Arabidopsis plants under methyl violet and UV-B irradiation also indicated significant increase in the expression level of CtF3′5′H1 with improved anthocyanin and flavonoid content, respectively. Noticeably, the virus-induced gene silencing (VIGS) assay of CtF3′5′H1 in safflower leaves also confirmed reduced anthocyanin accumulation. However, the CtF3′5′H1 suppression in safflower leaves under MeJA elicitation demonstrated significant increase in total flavonoid content. Together, our findings confirmed that CtF3′5′H1 is likely mediating methyl jasmonate-induced flavonoid biosynthesis in transgenic plants via enhanced anthocyanin accumulation.

Application of Elicitors, as Conventional and Nano Forms, in Viticulture: Effects on Phenolic, Aromatic and Nitrogen Composition of Tempranillo Wines

The phenolic, aromatic and nitrogen composition of a wine determines its organoleptic profile and quality. Elicitors have been used as a tool to stimulate the plant’s defense systems, favoring the synthesis of secondary metabolites. In this pioneering study, the elicitor methyl jasmonate in conventional form (MeJ) and in nanoparticle form (ACP-MeJ), with a concentration ten times lower, was applied in a Tempranillo vineyard over two seasons. The phenolic, nitrogen and volatile composition and the sensory properties of the MeJ-based wines were determined. The results showed that the effects of foliar applications of MeJ modify the wine composition. Thus, although the total concentration of most of the groups of phenolic compounds was not altered, several compounds, such as petunidin-3-glucoside, quercetin-3-glucoside, epigallocatechin and most of the stilbenes, increased, in both years, in the treated wines. Amino acids were influenced differently in each of the years studied, and volatile compounds generally did not improve in the treated wines. However, the ACP-MeJ wines were the best rated by the tasters, highlighting their equilibrium on the taste and their genuineness and odor quality. Therefore, foliar applications of ACP-MeJ can be considered a useful tool to improve wine quality.

Near-harvest application of methyl jasmonate affected phenolic content and antioxidant properties in "Thompson Seedless" grape

The influence of methyl jasmonate (MJ) preharvest treatment was investigated on some polyphenols and antioxidant systems in the "Thompson Seedless" table grape. The clusters were sprayed in the vineyard 2 days before harvest with 0, 1, 5, and 10 mM MJ. After picking, berries were stored for 6 days at 15°C, simulating marketing conditions. Total phenols and flavonoids were affected by MJ treatment, especially at 10 mM concentration, whereas total tannins were found to be unchanged. Antioxidant activity of the treated skin was noticeably higher compared with the control, together with PAL and POD activity. Although MJ had little effect on catechin and epicatechin, the levels of quercetin and rutin were noticeable. In addition, 5 and 10 mM MJ exerted a pronounced effect on transresveratrol content. These data showed that a single preharvest application close to the harvest time could be an effective treatment to promote the antioxidant properties of the grape.

Effects of Preharvest Methyl Jasmonate and Salicylic Acid Treatments on Growth, Quality, Volatile Components, and Antioxidant Systems of Chinese Chives

Methyl jasmonate (MeJA) and salicylic acid (SA) regulate the production of biologically active compounds in plants and stimulate the accumulation of plant aromatic substances. However, the underlying mechanisms of how MeJA and SA influence characteristic flavor compounds and the antioxidant activity of vegetables are poorly understood. Five MeJA and SA concentrations were used to investigate the dose-dependent effects of these phytohormones on the dry and fresh weight; chlorophyll abundance; the contents of vitamin C, soluble protein, and sugar, nitrate, total phenols, flavonoids, volatile components, and enzymatically produced pyruvic acid; and antioxidant activity in Chinese chive. We found that MeJA and SA at concentrations of 500 and 150 μM, respectively, significantly increased the levels of total chlorophyll, phenols and flavonoids, vitamin C, and volatile components and significantly reduced the accumulation of nitrate. In addition, compared with the control, 500 μM of MeJA significantly increased the soluble sugar and protein content, and 150 μM SA significantly increased the dry and fresh weight of Chinese chive. Furthermore, these concentrations of MeJA and SA significantly increased the enzymatic pyruvate content and the amount of sulfide and aromatic volatile compounds and improved the characteristic flavor compounds. The 2,2-diphenyl-1-picrylhydrazyl radical scavenging capacity, Trolox-equivalent antioxidant capacity, and ferric-reducing antioxidant capacity were significantly improved after a preharvest treatment with 500 μM MeJA and 150 μM SA, which could improve the antioxidant activity, thus improving the postharvest quality and preservation characteristics of Chinese chives. Taken together, a preharvest treatment with 500 μM MeJA and 150 μM SA is optimal to improve the growth, quality, antioxidant activity, and flavor of Chinese chive, thereby enhancing its commercial value.

Why Black Flowers? An Extreme Environment and Molecular Perspective of Black Color Accumulation in the Ornamental and Food Crops

Pollinators are attracted to vibrant flower colors. That is why flower color is the key agent to allow successful fruit set in food or ornamental crops. However, black flower color is the least attractive to pollinators, although a number of plant species produce black flowers. Cyanidin-based anthocyanins are thought to be the key agents to induce black color in the ornamental and fruit crops. R2R3-MYB transcription factors (TFs) play key roles for the tissue-specific accumulation of anthocyanin. MYB1 and MYB11 are the key TFs regulating the expression of anthocyanin biosynthesis genes for black color accumulation. Post-transcriptional silencing of flavone synthase II (FNS) gene is the technological method to stimulate the accumulation of cyanidin-based anthocyanins in black cultivars. Type 1 promoter of DvIVS takes the advantage of FNS silencing to produce large amounts of black anthocyanins. Exogenous ethylene application triggers anthocyanin accumulation in the fruit skin at ripening. Environment cues have been the pivotal regulators to allow differential accumulation of anthocyanins to regulate black color. Heat stress is one of the most important environmental stimulus that regulates concentration gradient of anthocyanins in various plant parts, thereby affecting the color pattern of flowers. Stability of black anthocyanins in the extreme environments can save the damage, especially in fruits, caused by abiotic stress. White flowers without anthocyanin face more damages from abiotic stress than dark color flowers. The intensity and pattern of flower color accumulation determine the overall fruit set, thereby controlling crop yield and human food needs. This review paper presents comprehensive knowledge of black flower regulation as affected by high temperature stress, and the molecular regulators of anthocyanin for black color in ornamental and food crops. It also discusses the black color-pollination interaction pattern affected by heat stress for food and ornamental crops.

Effects of exogenous methyl jasmonate and light condition on grape berry coloration and endogenous abscisic acid content

Suitable postharvest treatment methods were investigated to improve the color of grape berries. Culture solutions containing jasmonic acid (JA), methyl jasmonate (MeJA), and prohydrojasmon (PDJ) enhanced the skin coloration of grape berries ('Pione') harvested at the initial stage of coloration. MeJA vapor treatment under sealed conditions increased anthocyanin accumulation in grape berries ('AkiQueen' and 'Pione') harvested at the early stage of skin coloration. Furthermore, promoting skin coloration by MeJA vapor treatment was as effective in mature clusters as it was in detached berries. These effects were confirmed in light conditions but not in constant darkness. Our results showed that postharvest MeJA vapor treatment improved skin coloration in grapes. In addition, postharvest treatment with MeJA was found to have no effect on the endogenous abscisic acid content of grape berry skins. Therefore, we suggest that MeJA vapor treatment can be a useful and labor-saving method for the horticultural industry.

Effect of Methyl Jasmonate Doped Nanoparticles on Nitrogen Composition of Monastrell Grapes and Wines

Nitrogen composition on grapevines has a direct effect on the quality of wines since it contributes to develop certain volatile compounds and assists in the correct kinetics of alcoholic fermentation. Several strategies can be used to ensure nitrogen content in grapes and one of them could be the use of elicitors such as methyl jasmonate. The use of this elicitor has been proven to be efficient in the production of secondary metabolites which increases the quality of wines, but its use also has some drawbacks such as its low water solubility, high volatility, and its expensive cost. This study observes the impact on the amino acid and ammonium composition of must and wine of Monastrell grapes that have been treated with methyl jasmonate (MeJ) and methyl jasmonate n-doped calcium phosphate nanoparticles (MeJ-ACP). The first objective of this study was to compare the effect of these treatments to determine if the nitrogenous composition of the berries and wines increased. The second aim was to determine if the nanoparticle treatments showed similar effects to conventional treatments so that the ones which are more efficient and sustainable from an agricultural point of view can be selected. The results showed how both treatments increased amino acid composition in grapes and wines during two consecutive seasons and as well as the use of MeJ-ACP showed better results compared to MeJ despite using less quantity (1 mM compared to 10 mM typically). So, this application form of MeJ could be used as an alternative in order to carry out a more efficient and sustainable agriculture.

Characterization and Action Mechanism Analysis of VvmiR156b/c/d-VvSPL9 Module Responding to Multiple-Hormone Signals in the Modulation of Grape Berry Color Formation

In recent years, more and more reports have shown that the miR156-SPL module can participate in the regulation of anthocyanin synthesis in plants. However, little is known about how this module responds to hormonal signals manipulating this process in grapes. In this study, exogenous GA, ABA, MeJA, and NAA were used to treat the 'Wink' grape berries before color conversion, anthocyanin and other related quality physiological indexes (such as sugar, aroma) were determined, and spatio-temporal expression patterns of related genes were analyzed. The results showed that the expression levels of VvmiR156b/c/d showed a gradually rising trend with the ripening and color formation of grape berries, and the highest expression levels were detected at day 28 after treatment, while the expression level of VvSPL9 exhibited an opposite trend as a whole, which further verifies that VvmiR156b/c/d can negatively regulate VvSPL9. Besides, VvmiR156b/c/d was positively correlated with anthocyanin content and related genes levels, while the expression pattern of VvSPL9 showed a negative correlation. Analysis of promoter cis-elements and GUS staining showed that VvmiR156b/c/d contained a large number of hormone response cis-elements (ABA, GA, SA, MeJA, and NAA) and were involved in hormone regulation. Exogenous ABA and MeJA treatments significantly upregulated the expression levels of VvmiR156b/c/d and anthocyanin structural genes in the early stage of color conversion and made grape berries quickly colored. Interestingly, GA treatment downregulated the expression levels of VvmiR156b/c/d and anthocyanin structural genes in the early color-change period, but significantly upregulated in the middle color-change and ripening stages, therefore GA mainly modulated grape berry coloring in the middle- and late-ripening stages. Furthermore, NAA treatment downregulated the expression levels of VvmiR156b/c/d and anthocyanin structural genes and delayed the peak expression of genes. Meanwhile, to further recognize the potential functions of VvmiR156b/c/d, the mature tomato transient trangenetic system was utilized in this work. Results showed that transient overexpression of VvmiR156b/c/d in tomato promoted fruit coloring and overexpression of VvSPL9 inhibited fruit coloration. Finally, a regulatory network of the VvmiR156b/c/d-VvSPL9 module responsive to hormones modulating anthocyanin synthesis was developed. In conclusion, VvmiR156b/c/d-mediated VvSPL9 participated in the formation of grape color in response to multi-hormone signals.

Transcriptome analysis provides new insights into the transcriptional regulation of methyl jasmonate-induced flavonoid biosynthesis in pear calli

BACKGROUND

Flavonoid biosynthesis is strongly influenced by phytohormones. For example, methyl jasmonate (MeJA) enhances the flavonoid accumulation in pear. However, the molecular mechanism underlying the MeJA-induced flavonoid biosynthesis in pear is largely uncharacterized. Therefore, the transcriptome of pear calli treated with MeJA was analyzed to elucidate the mechanism regulating MeJA-mediated flavonoid biosynthesis.

RESULTS

The application of exogenous MeJA significantly enhanced flavonoid accumulation, especially anthocyanin, in pear calli. A weighted gene co-expression network analysis identified the differentially expressed genes associated with MeJA-induced flavonoid biosynthesis. The MeJA treatment upregulated the expression of the flavonoid biosynthesis pathway structural genes (PcCHS, PcCHI, PcF3H, PcDFR, PcANS, PcANR2a, and PcLAR1). The MYB family members were the main transcription factors regulating the MeJA-induced flavonoid biosynthesis, but the bHLH, AP2-EREBP, NAC, WRKY, and TIFY families were also involved. In addition to PcMYB10, which is a known positive regulator of anthocyanin biosynthesis in pear, several novel MYB candidates that may regulate flavonol and proanthocyanidin biosynthesis were revealed. Yeast two-hybrid and bimolecular fluorescence complementation assays demonstrated that PcMYB10 and PcMYC2 can directly interact with each other and bind to JAZ repressors (PcJAZ1 and PcJAZ2).

CONCLUSIONS

The PcMYB10-PcMYC2 molecular complex is likely involved in the regulation of jasmonate-mediated flavonoid biosynthesis at the transcript level. The data generated in this study may clarify the transcriptional regulatory network associated with the MeJA-induced flavonoid accumulation in pear calli and provide a solid foundation for future studies.

Comparative transcriptome analysis reveals fruit discoloration mechanisms in postharvest strawberries in response to high ambient temperature

The aim of this study was to examine both physiological and molecular evidences related to fruit discoloration in postharvest strawberries under high ambient temperature. The results showed the total anthocyanin and their main components in the strawberries under 35 °C were greatly increased due to the significant up-regulations of anthocyanin biosynthetic genes and transportation genes. High ambient temperature greatly improved the activities of peroxidase (POD) and enhanced gene expressions of POD3, POD6 and POD63. At the same time, high storage temperature activated laccase genes expression including laccase-9 and laccase-14, which was closely related to anthocyanin degradation. Levels of reactive oxygen species (ROS) metabolism were also increased under high ambient temperature at transcript levels. Therefore, we concluded that high ambient temperature could enhance anthocyanin accumulation and degradation at the same time, which maybe the main reasons for the fruits discoloration of postharvest strawberries under high ambient temperature.

Effect of elicitors on the evolution of grape phenolic compounds during the ripening period

BACKGROUND

The effect of the application of benzothiadiazole (BTH) and methyl jasmonate (MeJ) at veraison on the phenolic composition of grapes from three varieties (Monastrell, Syrah and Merlot) was studied during the ripening period, using HPLC techniques to measure flavonols, anthocyanins and tannins.

RESULTS

The effects of the treatments differed in the three varieties, and the maximum concentration of phenolic compounds was not always reached at the end of the ripening period but some days before harvest. At the end of ripening both treated Syrah grapes only differed from control grapes in the flavonol concentration, whereas MeJ-treated Merlot grapes presented higher anthocyanin and skin tannin contents than the control and BTH-treated grapes. Only the anthocyanin content was significantly higher in treated Monastrell grapes at the moment of harvest.

CONCLUSION

The results indicate that the moment of elicitor treatment should be more studied since differences between treated and control grapes were, in general greater several days before harvest in all three varieties. © 2016 Society of Chemical Industry.

New Procedure to Obtain Polyphenol-Enriched Grapes Based on the Use of Chemical Elicitors

The effect of the postharvest treatment of methyl jasmonate enantiomers in conjunction with ethanol on bioformation of resveratrol and quercetin glycosides in grapes was evaluated. The antioxidant activity of treated grape extracts as compared with untreated extracts was also assayed. Exogenous (-)-methyl jasmonate in combination with ethanol induced a significant increase in the levels of resveratrol (from 27 to 39 μg g(-1)), quercetin-3-O-glucoside (from 59 to 136 μg g(-1)), quercetin-3-O-galactoside (from 398 to 807 μg g(-1)) and quercetin-3-O-rutinoside (from 23 to 43 μg g(-1)). (+)-Methyl jasmonate with ethanol also resulted in increase of quercetin-3-O-glucoside and quercetin-3-O-rutinoside. However, no (+)-methyl jasmonate effect was observed for resveratrol and quercetin-3-O-galactoside. Both (-)- and (+)-methyl jasmonate treatments provided with extracts with higher antioxidant activity. From the results found in the present work postharvest treatment with (-)-methyl jasmonate in conjunction with ethanol is proposed as a mean to obtain polyphenol-enriched grape extracts with improved antioxidant properties. The procedure here developed is proposed as a mean to obtain functional grapes. Extracts obtained from grapes treated with (-)-methyl jasmonate with ethanol can be particularly useful for industry due to their high antioxidant capacity.

Methyl Jasmonate: An Alternative for Improving the Quality and Health Properties of Fresh Fruits

Methyl jasmonate (MeJA) is a plant growth regulator belonging to the jasmonate family. It plays an important role as a possible airborne signaling molecule mediating intra- and inter-plant communications and modulating plant defense responses, including antioxidant systems. Most assessments of this compound have dealt with post-harvest fruit applications, demonstrating induced plant resistance against the detrimental impacts of storage (chilling injuries and pathogen attacks), enhancing secondary metabolites and antioxidant activity. On the other hand, the interactions between MeJA and other compounds or technological tools for enhancing antioxidant capacity and quality of fruits were also reviewed. The pleiotropic effects of MeJA have raisen numerous as-yet unanswered questions about its mode of action. The aim of this review was endeavored to clarify the role of MeJA on improving pre- and post-harvest fresh fruit quality and health properties. Interestingly, the influence of MeJA on human health will be also discussed.