Impact of jasmonates on safety, productivity and physiology of food crops

Impact of 24-epibrassinoliode and methyl jasmonate on quality of Red Delicious apples

BACKGROUND

Changes in apple fruit quality indices in response to foliar spray with 24-epibrassinolide (EBL) at 0 and 1 μmol L-1 and methyl jasmonate (MeJA) at 0 and 0.5 μmol L-1 , as well as the combination of these phytohormones, were investigated at harvest and during cold storage.

RESULTS

Both phytohormones synergistically enhanced the fruit firmness, specific weight, size, fresh weight, water content, total antioxidant activity, total phenolics, ascorbic acid, total anthocyanins, total soluble solids/titratable acidity ratio and precocity. In addition, the fruit abscission pattern was changed in response to different treatments. Treated fruit exhibited lower weight loss and internal breakdown symptoms and higher total soluble solids index, firmness and phytochemicals during cold storage. A negative correlation was seen between fruit mass, firmness, specific weight, antioxidant activity, total phenolics and vitamin C content with internal breakdown occurrence and weight loss.

CONCLUSION

Foliar spray with EBL and MeJA during the growth season is a good environmental friendly and safe method for enhancing the apple fruit different quality parameters, marketability and postharvest life. © 2023 Society of Chemical Industry.

Interkingdom Hormonal Regulations between Plants and Animals Provide New Insight into Food Safety

Food safety has become an attractive topic among consumers. Raw material production for food is also a focus of social attention. As hormones are widely used in agriculture and human disease control, consumers' concerns about the safety of hormone agents have never disappeared. The present review focuses on the interkingdom regulations of exogenous animal hormones in plants and phytohormones in animals, including physiology and stress resistance. We summarize these interactions to give the public, researchers, and policymakers some guidance and suggestions. Accumulated evidence demonstrates comprehensive hormonal regulation across plants and animals. Animal hormones, interacting with phytohormones, help regulate plant development and enhance environmental resistance. Correspondingly, phytohormones may also cause damage to the reproductive and urinary systems of animals. Notably, the disease-resistant role of phytohormones is revealed against neurodegenerative diseases, cardiovascular disease, cancer, and diabetes. These resistances derive from the control for abnormal cell cycle, energy balance, and activity of enzymes. Further exploration of these cross-kingdom mechanisms would surely be of greater benefit to human health and agriculture development.

Investigation of pectolytic and PR genes expression, quality and phytochemical contents in organic and non-organic table grapes at harvest and during storage

The demand for organic table grapes is increasing worldwide. However, comprehensive information of quality parameters and phytochemical compounds in organically grown fruit remain unclear. Furthermore, table grapes are perishable and postharvest quality retention and waste prevention is very important. In this study we have compared the differences between organic and non-organic table grapes in terms of phytochemical compounds and quality parameters as well as the changes in the expression levels of pathogen related and lytic genes during storage. Organic fruit showed higher levels of phenolics, flavonoids, caffeic acid, hydrogen peroxide, protein content, antioxidant and anti-stress enzymes and total antioxidant activities at harvest and during storage. Although, the expression levels of polygalactronases, pectin methyl esterase, chitinase and glucanase genes was lower in organically grown table grapes at harvest, but the expression of all these genes was significantly increased during cold storage. After 60 days of cold storage the expression levels of pectin methyl esterase, chitinase and glucanase genes was significantly higher than the conventionally grown grape berries in organic ones. The highest expression of polygalacturonase was recorded in organic samples after 30 days of storage. There was no significant difference between the two types of table grapes for decay extension and tissue deterioration rate. The results of this study indicate that due to higher levels of phytochemicals and antioxidant compounds the organic table grapes have a higher nutritional quality. Furthermore, the increase in PR and pectolytic genes expression levels is enough for decreasing the fruit susceptibility to decay pathogens and enhancing the postharvest life of organic grapes.

Therapeutic Potential of Plant Oxylipins

For immobile plants, the main means of protection against adverse environmental factors is the biosynthesis of various secondary (specialized) metabolites. The extreme diversity and high biological activity of these metabolites determine the researchers' interest in plants as a source of therapeutic agents. Oxylipins, oxygenated derivatives of fatty acids, are particularly promising in this regard. Plant oxylipins, which are characterized by a diversity of chemical structures, can exert protective and therapeutic properties in animal cells. While the therapeutic potential of some classes of plant oxylipins, such as jasmonates and acetylenic oxylipins, has been analyzed thoroughly, other oxylipins are barely studied in this regard. Here, we present a comprehensive overview of the therapeutic potential of all major classes of plant oxylipins, including derivatives of acetylenic fatty acids, jasmonates, six- and nine-carbon aldehydes, oxy-, epoxy-, and hydroxy-derivatives of fatty acids, as well as spontaneously formed phytoprostanes and phytofurans. The presented analysis will provide an impetus for further research investigating the beneficial properties of these secondary metabolites and bringing them closer to practical applications.

Identification and Quantification of Key Phytochemicals, Phytohormones, and Antioxidant Properties in Coccinia grandis during Fruit Ripening

Coccinia grandis contains secondary metabolites, such as flavonoids, phenolic acids, terpenoids, alkaloids, sterols, and glycosides, which are known to have in vitro antioxidant, antidiabetic, anti-inflammatory, and antidyslipidemic activities. C. grandis fruits change dramatically during ripening, and the differences in the phytochemicals contribute to various uses. This study reports the phytochemical compounds and antioxidant activities during ripening of C. grandis for the first time. Characterizations were conducted on the physiologically active substances in C. grandis fruits at three ripening stages, and a total of 25 peaks were identified. Key phytochemicals in the ripening stages of C. grandis were identified, and the major substances that contributed to antioxidant properties were selected and quantitatively analyzed. Although the concentration of tiliroside increased during aging, hydroxycinnamic acid (chlorogenic and p-coumaric acids), flavonols (rutin), and triterpenes (cucurbitacins B and D) with antioxidant effects decreased. Therefore, phenolic compounds and cucurbitacins dominate immature C. grandis quantitatively. Regarding phytohormones, the gibberellin A4 content decreased as the fruits matured, but indoleacetic acid and salicylic acid increased with fruit maturity. The antioxidant capacities determined by DPPH and ABTS consistently decreased with increasing maturity. Accordingly, the extracts of immature C. grandis fruits have high levels of bioactive compounds and can be used to develop food additives and health supplements.

The Jasmonic Acid Signaling Pathway is Associated with Terpinen-4-ol-Induced Disease Resistance against Botrytis cinerea in Strawberry Fruit

Terpinen-4-ol, the main component of tea tree oil, markedly increases the disease resistance of postharvest strawberry fruit. To understand the mechanism underlying the enhancement of disease resistance, a high-throughput RNA-seq was used to analyze gene transcription in terpinen-4-ol-treated and untreated fruit. The results show that terpinen-4-ol induces the expression of genes in the jasmonic acid (JA) biosynthesis pathway, secondary metabolic pathways such as phenylpropanoid biosynthesis, and pathways involved in plant-pathogen interactions. Terpinen-4-ol treatment reduced disease incidence and lesion diameter in strawberry fruit inoculated with Botrytis cinerea. Terpinen-4-ol treatment enhanced the expression of genes involved in JA synthesis (FaLOX, FaAOC, and FaOPR3) and signaling (FaCOI1), as well as genes related to disease defense (FaPAL, FaCHI, and FaGLU). In contrast, treatment with the JA biosynthesis inhibitor salicylhydroxamic acid (SHAM) accelerated disease development and inhibited the induction of gene expressions by terpinen-4-ol. We conclude that the JA pathway participates in the induction of disease resistance by terpinen-4-ol in strawberry fruit. More generally, the results illuminate the mechanisms by which disease resistance is enhanced by essential oils.

Exogenous Methyl Jasmonate Improves Cold Tolerance with Parallel Induction of Two Cold-Regulated (COR) Genes Expression in Triticum aestivum L

Methyl jasmonate (MJ) is an important plant growth regulator that plays a key role in tolerance to biotic and abiotic stresses. In this research, the effects of exogenous MJ on cold tolerance, photosynthesis, activity and gene expression of antioxidant enzymes, proline accumulation, and expression of cold-regulated (COR) genes in wheat seedlings under low temperature (4 °C) were investigated. Exogenous MJ treatment (1 µM) promoted wheat cold tolerance before and during cold exposure. Low temperature significantly decreased photosynthetic parameters, whereas MJ application led to their partial recovery under cold exposure. Hydrogen peroxide (H2O2) and malondialdehyde (MDA) levels increased in response to low temperature, and this was counteracted by MJ application. Exogenous MJ significantly enhanced the activities of antioxidant enzymes and upregulated the expression of MnSOD and CAT during cold exposure. MJ application also led to enhanced proline content before 4 °C exposure, whereas the P5CS gene expression was upregulated by MJ's presence at both normal (22 °C) and low (4 °C) temperatures. It was also shown that MJ tended to upregulate the expression of the COR genes WCS19 and WCS120 genes. We conclude that exogenous MJ can alleviate the negative effect of cold stress thus increasing wheat cold tolerance.

Effects of exogenous methyl jasmonate on quality and preservation of postharvest fruits: A review

Methyl jasmonate (MeJA) is a volatile hormone involved in a number of plant processes, acting as a signal in response to external stresses and modulating the biosynthesis of other phytohormones. Here, we are reviewing for the first time all reports related to the effects of exogenous MeJA on postharvest fruits. Application of MeJA during preharvest and postharvest stages has been demonstrated to enhance fruit antioxidant capacity and phenolics content, which in turn extended fruit shelf-life, enhanced fruit quality and reduced chilling injury. The postharvest application of MeJA has been reported to alter volatiles pattern and to enhance the innate disease resistance of postharvest fruits against pathogenic fungi. The results obtained using different treatment conditions, such as temperature, storage time and concentration, have been highlighted and compared along the manuscript in order to provide new insights on the applicability of MeJA for enhancing postharvest fruit quality and preservation.

Jasmonates Alleviate the Harm of High-Temperature Stress During Anthesis to Stigma Vitality of Photothermosensitive Genetic Male Sterile Rice Lines

Using photothermosensitive genic male sterile (PTSGMS) rice (Oryza sativa L.) lines to produce hybrids can obtain great heterosis. However, PTSGMS rice lines exhibit low stigma vitality when high-temperature (HT) stress happens during anthesis. Jasmonates (JAs) are novel phytohormones and play vital roles in mediating biotic and abiotic stresses. Little is known, however, if and how JAs could alleviate the harm of HT stress during anthesis to the stigma vitality of PTSGMS lines. This study investigated the question. Two PTSGMS lines and one restorer line of rice were pot-grown and subjected to normal temperature and HT stress during anthesis. The stigma exertion rate, sigma fresh weight, stigma area, contents of JAs, hydrogen peroxide (H₂O₂), and ascorbic acid (AsA), activity of catalase in stigmas, and the number of pollens germinated on the stigma of PTSGMS lines were determined. The results showed that a rice line with higher JAs content in the stigma under HT stress showed lower H₂O₂ content, higher AsA content and catalase activity in stigmas, larger stigma area, heavier stigma fresh weight, more pollens germinated on the stigma, and higher fertilization and seed-setting and rates. Applying methyl JAs during anthesis to rice panicles decreased the accumulation of reactive oxygen species and enhanced stigma vitality, thereby increasing fertilization and seed-setting rates of the hybrids of PTSGMS rice lines under HT stress. The results demonstrate that JAs attenuate the injury of HT stress to the stigma vitality of PTSGMS rice lines through enhancing antioxidant ability.

Nitric Oxide and Hydrogen Peroxide Are Involved in Methyl Jasmonate-Regulated Response against Botrytis cinerea in Postharvest Blueberries

The involvement and the relationship between nitric oxide (NO) and hydrogen peroxide (H₂O₂) in methyl jasmonate (MeJA)-induced immune responses in blueberries against Botrytis cinerea was explored using diphenylene iodonium (DPI, NADPH oxidase inhibitor) and 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO, NO scavenger). MeJA induced NO and H₂O₂ burst and enhanced the resistance of blueberries by elevating defense-related enzymes and the phenylpropanoid pathway. However, the above impacts stimulated by MeJA were weakened by DPI and destroyed by cPTIO. Furthermore, cPTIO abolished the increment in H₂O₂ by regulating the activities of NADPH oxidase, superoxide dismutase, catalase, and ascorbate peroxidase, whereas DPI weakened the increase in H₂O₂ but barely affected the generation of NO and the activity of nitric oxide synthase elevated by MeJA. These results indicated that NO and H₂O₂ were involved in the MeJA-induced resistance in blueberries, and NO worked upstream of H₂O₂ in this process.

Methyl jasmonate induces the resistance of postharvest blueberry to gray mold caused by Botrytis cinerea

BACKGROUND

The effects of postharvest methyl jasmonate (MeJA) treatment (50 μmol L^-1 ) on the control of gray mold caused by Botrytis cinerea in blueberry fruit were evaluated by analyzing (i) the levels of disease resistance signals; (ii) the activity of enzymes involved in antioxidant system, disease resistance and phenylpropanoid pathway, and (iii) the secondary metabolite content.

RESULTS

The results indicated that MeJA treatment significantly restrained the development of gray mold decay in blueberries. The treatment induced a nitric oxide (NO) burst and increased the endogenous hydrogen peroxide (H₂ O₂ ) content in the earlier period of storage. The enhanced NO and H₂ O₂ generation by MeJA treatment might serve as a signal to induce resistance against B. cinerea infection. Furthermore, in inoculated fruit, MeJA treatment significantly promoted antioxidant enzymes and defense-related enzyme activity, which included superoxide dismutase, catalase, ascorbate peroxidase, chitinase, and β-1,3-glucanase, and the degree of membrane lipid peroxidation was reduced. The MeJA treatment enhanced the phenylpropanoid pathway by provoking phenylalanine ammonialyase, cinnamate 4-hydroxylase, and 4-coumarate CoA ligase activity, which was accompanied by elevated levels of phenolics and flavonoids in blueberry fruit.

CONCLUSION

These results suggested that MeJA could induce the disease resistance of blueberries against B. cinerea by regulating the antioxidant enzymes, defense-related enzymes, and the phenylpropanoid pathway through the activation of signaling molecules.

Priming of Defense Systems and Upregulation of MYC2 and JAZ1 Genes after Botrytis cinerea Inoculation in Methyl Jasmonate-Treated Strawberry Fruits

Several attempts have been made to study the effects of methyl jasmonate (MeJA) on plants in the past years. However, the comparative effects of the number and phenological time of MeJA applications on the activation of defense systems is currently unknown in strawberries. In the present research, we performed three field treatments during strawberry (Fragaria× ananassa 'Camarosa') fruit development and ripening which consisted of differential MeJA applications at flowering (M3), and the large green (M2 and M3) and red ripe (M1, M2, and M3) fruit stages. We also checked changes in gene expression related to plant defense against Botrytis cinerea inoculation post-harvest. In M3 treatment, we observed an upregulation of the anthocyanin and lignin contents and the defense-related genes, encoding for chitinases, β-1,3-glucanases and polygalacturonase-inhibiting proteins, after harvest (0 hpi), along with the jasmonate signaling-related genes FaMYC2 and FaJAZ1 at 48 h after B. cinerea inoculation (48 hpi) during postharvest storage. Although we did not find differences in gray mold incidence between the MeJA treatments and control, these results suggest that preharvest MeJA treatment from the flowering stage onwards (M3) primes defense responses mediated by the upregulation of different defense-related genes and retains the upregulation of MYC2 and JAZ1 at 48 hpi.