Preharvest Methyl Jasmonate Treatment Increased the Antioxidant Activity and Glucosinolate Contents of Hydroponically Grown Pak Choi

Antioxidant Profile, Amino Acids Composition, and Physicochemical Characteristics of Cherry Tomatoes Are Associated with Their Color

This study was conducted to characterize different colored lines of cherry tomatoes and derive information regarding their metabolite accumulation. Different colored cherry tomato cultivars, namely 'Jocheong', 'BN Satnolang', 'Gold Chance', 'Black Q', and 'Snacktom', were assessed for their firmness, taste characteristics, and nutritional metabolites at the commercial ripening stage. The cultivars demonstrated firmness to withstand impacts during harvesting and postharvest operations. The significant variations in the Brix to acid ratio (BAR) and the contents of phenylalanine, glutamic acid, and aspartic acid highlight the distinct taste characteristics among the cultivars, and the nutritional metabolites are associated with the color of the cultivars. The cultivar choices would be the black-colored 'Black Q' for chlorophylls, β-carotene, total flavonoids, and anthocyanins; the red-colored 'Snacktom' for lycopene; the orange-colored 'Gold Chance' for total phenolics; and the green-colored 'Jocheong' for chlorophylls, vitamin C, GABA, glutamic acid, essential amino acids, and total free amino acids. The antioxidant capacity varied among the cultivars, with 'Gold Chance' consistently exhibiting the highest activity across the four assays, followed by 'Snacktom'. This study emphasizes the importance of screening cultivars to support breeding programs for improving the nutritional content and encourages the inclusion of a diverse mix of different colored cherry tomatoes in packaging to obtain the cumulative or synergistic effects of secondary metabolites.

Preharvest Methyl Jasmonate Treatment Affects the Mineral Profile, Metabolites, and Antioxidant Capacity of Radish Microgreens Produced without Substrate

This study investigated the impact of Methyl Jasmonate (MeJA) application on the nutritional content and yield of five different colored radish microgreens. Microgreens were produced without substrate and subjected to 0.5 mM and 1.0 mM MeJA treatments on the 7th day, three days before harvest. The parameters measured included yield, dry matter, minerals, amino acids, secondary metabolites such as chlorophylls (Chls), anthocyanins, flavonoids, phenolics, glucosinolates (GSLs), vitamin C, and antioxidant capacity. MeJA at 1.0 mM generally improved yield and dry weight across cultivars, and all microgreens exhibited rich mineral and amino acid composition, with the influence of cultivar being more significant than MeJA treatment. However, MeJA enhanced all cultivars' anthocyanins, GSLs, phenolics, flavonoids, and antioxidant activities. Generally, as the antioxidant capacity is the primary factor influencing the nutritional quality of microgreens, MeJA-treated microgreens, especially with selected superior cultivars such as 'Asia purple' and 'Koregon red', could offer a potential for cultivation of value-added, eco-friendly microgreens with substrate-free cultivation.

Identification of Potential Factors for the Promotion of Fucoxanthin Synthesis by Methyl Jasmonic Acid Treatment of Phaeodactylum tricornutum

Fucoxanthin, a vital secondary metabolite produced by marine diatoms, has great economic value and research potential. However, its popularization and application have been greatly restricted due to its low content, difficult extraction, and high production cost. Methyl jasmonic acid (MeJA) exerts similar inductive hormones in the growth and development as well as metabolic processes of plants. In Phaeodactylum tricornutum (P. tricornutum), MeJA treatment can increase fucoxanthin content. In this study, the effects of different concentrations of MeJA on the cell growth and the fucoxanthin content of P. tricornutum were explored. Meanwhile, this study used high-throughput sequencing technology for transcriptome sequencing of P. tricornutum and subsequently performed differential gene expression analysis, gene ontology (GO) enrichment analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis, and weighted gene co-expression network analysis (WGCNA) for screening the hub genes for the promotion of fucoxanthin synthesis with MeJA-treated P. tricornutum. On this basis, the functions of the hub genes for the promotion of fucoxanthin synthesis with MeJA-treated P. tricornutum were further analyzed. The results revealed that the carotenoid synthesis-related genes PHATRDRAFT_54800 and PHATRDRAFT_20677 were the hub genes for the promotion of fucoxanthin synthesis with MeJA-treated P. tricornutum. PHATRDRAFT_54800 may be a carotenoid isomerase, while PHATRDRAFT_20677 may be involved in the MeJA-stimulated synthesis of fucoxanthin by exerting the role of SDR family NAD(P)-dependent oxidoreductases.

Radish microgreens produced without substrate in a vertical multi-layered growing unit are rich in nutritional metabolites

Growing microgreens on trays without substrate in a vertical multilayered growing unit offers several advantages over traditional agriculture methods. This study investigated the yield performance and nutritional quality of five selections of radish microgreens grown in sprouting trays, without a substrate using only water, in an indoor multilayer cultivation system using artificial light. Various parameters were measured, including fresh weight, dry matter, chlorophyll, minerals, amino acids, phenolics, flavonoids, anthocyanins, vitamin C, glucosinolates, and antioxidant activity with four different in vitro assays. After ten days, the biomass had increased by 6-10 times, and the dry matter varied from 4.75-7.65%. The highest yield was obtained from 'Asia red', while the lowest was from 'Koregon red'. However, 'Koregon red' and 'Asia red' had the highest dry matter. 'Asia red' was found to have the highest levels of both Chls and vitamin C compared to the other cultivars, while 'Koregon red' exhibited the highest levels of total phenolics and flavonoids. Although variations in the levels of individual glucosinolates were observed, there were no significant differences in the total content of glucosinolates among the five cultivars. 'Asia purple' had the highest anthocyanin content, while 'Asia green 2' had the lowest. The K, Mg, and Na concentrations were significantly highest in 'Asia green 2', and the highest Ca was recorded in 'Asia purple'. Overall, 'Asia purple' and 'Koregon red' were the best cultivars in terms of nutritional quality among the tested radish microgreens. These cultivars exhibited high levels of dry weight, total phenolics, flavonoids, anthocyanins, essential and total amino acids, and antioxidant activities. Moreover, the implementation of this vertical cultivation method for microgreens, which relies solely on water and seeds known for their tall shoots during the sprouting could hold promise as a sustainable approach. This method can effectively be utilized for cultivar screening and fulfilling the nutritional and functional needs of the population while minimizing the environmental impacts associated with traditional agriculture practices.

Response of Thymus lotocephalus In Vitro Cultures to Drought Stress and Role of Green Extracts in Cosmetics

The impact of drought stress induced by polyethylene glycol (PEG) on morphological, physiological, (bio)chemical, and biological characteristics of Thymus lotocephalus López and Morales shoot cultures have been investigated, as well as the potential of iron oxide nanoparticles, salicylic acid, and methyl jasmonate (MeJA) as alleviating drought stress agents. Results showed that PEG caused oxidative stress in a dose-dependent manner, raising H₂O₂ levels and reducing shoots’ growth, photosynthetic pigment contents, and phenolic compounds production, especially phenolic acids, including the major compound rosmarinic acid. Moreover, Fourier Transform Infrared Spectra analysis revealed that PEG treatment caused changes in shoots’ composition, enhancing terpenoids biosynthesis. PEG also decreased the biological activities (antioxidant, anti-tyrosinase, and photoprotective) of the eco-friendly extracts obtained with a Natural Deep Eutectic Solvent. MeJA was the most efficient agent in protecting cells from oxidative damage caused by drought, by improving the biosynthesis of phenolics, like methyl 6-O-galloyl-β-D-glucopyranoside and salvianolic acids, as well as improving the extracts’ antioxidant activity. Altogether, the obtained results demonstrated a negative impact of PEG on T. lotocephalus shoots and an effective role of MeJA as a mitigating agent of drought stress. Additionally, extracts showed a good potential to be used in the cosmetics industry as skincare products.

Preharvest Methyl Jasmonate Treatment Increased Glucosinolate Biosynthesis, Sulforaphane Accumulation, and Antioxidant Activity of Broccoli

Broccoli is becoming increasingly popular among consumers owing to its nutritional value and rich bioactive compounds, such glucosinolates (GSLs) and hydrolysis products, which are secondary metabolites for plant defense, cancer prevention, and higher antioxidant activity for humans. In this study, 40 μmol/L methyl jasmonate (MeJA) was sprayed onto broccoli from budding until harvest. The harvested broccoli florets, stem, and leaves were used to measure the contents of GSLs, sulforaphane, total phenolics, and flavonoids, as well as myrosinase activity, antioxidant activity, and gene expression involved in GSL biosynthesis. The overall results revealed that GSL biosynthesis and sulforaphane accumulation were most likely induced by exogenous MeJA treatment by upregulating the expression of CYP83A1, SUR1, UGT74B1, and SOT18 genes. Exogenous MeJA treatment more remarkably contributed to the increased GSL biosynthesis in broccoli cultivars with low-level GSL content (Yanxiu) than that with high-level GSLs (Xianglv No.3). Moreover, MeJA treatment had a more remarkable increasing effect in broccoli florets than stem and leaves. Interestingly, total flavonoid content substantially increased in broccoli florets after MeJA treatment, but total phenolics did not. Similarly, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity, trolox-equivalent antioxidant capacity (ABTS), and ferric-reducing antioxidant power (FRAP) were higher in broccoli floret after MeJA treatment. In conclusion, MeJA mediated bioactive compound metabolism, had positive effects on GSL biosynthesis, sulforaphane, and flavonoids accumulation, and showed positive correlation on inducing higher antioxidant activities in broccoli floret. Hence, preharvest supplementation with 40 μM MeJA could be a good way to improve the nutritional value of broccoli florets.

Comparative Transcriptome Analysis of Softening and Ripening-Related Genes in Kiwifruit Cultivars Treated with Ethylene

This work presents the transcriptome analysis of green ‘Hayward’ (Actinidia deliciosa) and gold ‘Haegeum’ (Actinidia chinensis) kiwifruit cultivars after treatment with ethylene for three days at 25 °C. Illumina high-throughput sequencing platform was used to sequence total mRNAs and the transcriptome gene set was constructed by de novo assembly. A total of 1287 and 1724 unigenes were differentially expressed during the comparison of ethylene treatment with control in green ‘Hayward’ and gold ‘Haegeum’, respectively. From the differentially expressed unigenes, 594 and 906 were upregulated, and 693 and 818 were downregulated in the green and gold kiwifruit cultivars, respectively, when treated with ethylene. We also identified a list of genes that were expressed commonly and exclusively in the green and gold kiwifruit cultivars treated with ethylene. Several genes were expressed differentially during the ripening of kiwifruits, and their cumulative effect brought about the softening- and ripening-related changes. This work also identified and categorized genes related to softening and other changes during ripening. Furthermore, the transcript levels of 12 selected representative genes from the differentially expressed genes (DEGs) identified in the transcriptome analysis were confirmed via quantitative real-time PCR (qRT-PCR) to validate the reliability of the expression profiles obtained from RNA-Seq. The data obtained from the present study will add to the information available on the molecular mechanisms of the effects of ethylene during the ripening of kiwifruits. This study will also provide resources for further studies of the genes related to ripening, helping kiwifruit breeders and postharvest technologists to improve ripening quality.

Prestorage High CO2 and 1-MCP Treatment Reduce Chilling Injury, Prolong Storability, and Maintain Sensory Qualities and Antioxidant Activities of “Madoka” Peach Fruit

Cold storage is widely used to prolong the storability of peach fruit. However, prolonged storage at low temperatures results in chilling injury (CI) in some susceptible peach cultivars during or after cold storage. Prestorage high CO₂ and 1-methylcyclopropene (1-MCP) treatments are among the methods reported to alleviate CI and maintain the firmness of peach fruit. Hence, this study investigated CI, ripening-related physicochemical parameters, sensory qualities, total phenolics and flavonoids, and antioxidant activities of “Madoka” peach fruit to observe the effectiveness of prestorage treatment with high CO₂ and 1-MCP during the storage at 0 and 5°C. Based on the CI index, control fruits were acceptable for marketing up to 20 and 16 days of storage at 0 and 5°C, respectively, while the treated fruits could be marketable up to 28 days of storage. The results of firmness and firmness-related parameters [pectin content and polygalacturonase (PG) activity] also revealed that both high CO₂ and 1-MCP treatments were effective in delaying the ripening process of Madoka peach, and the storage at 0°C showed better results than at 5°C. However, based on the overall sensory evaluation results, the treated and control fruits were acceptable for marketing up to 20 and 12 days of storage, respectively, in both storage conditions. After deciding on fruit marketability based on the combined objective postharvest quality parameters and subjective sensory qualities, we analyzed the changes in total phenolics, flavonoids, and antioxidant activities at harvest, on the 12 and 20th days of cold storage. Storage of Madoka peach at 0°C maintained total phenolics, flavonoids, and antioxidant activities regardless of prestorage treatment with high CO₂ and 1-MCP. In summary, storing Madoka peach fruit at 0°C after treating it with 30% CO₂ for 6 h or 0.5 μl L^–1 1-MCP for 24 h reduces CI, prolongs storability, and maintains sensory quality and antioxidant properties.

Selenium, Sulfur, and Methyl Jasmonate Treatments Improve the Accumulation of Lutein and Glucosinolates in Kale Sprouts

Kale sprouts contain health-promoting compounds that could be increased by applying plant nutrients or exogenous phytohormones during pre-harvest. The effects of selenium (Se), sulfur (S), and methyl jasmonate (MeJA) on lutein, glucosinolate, and phenolic accumulation were assessed in kale sprouts. Red Russian and Dwarf Green kale were chamber-grown using different treatment concentrations of Se (10, 20, 40 mg/L), S (30, 60, 120 mg/L), and MeJA (25, 50, 100 µM). Sprouts were harvested every 24 h for 7 days to identify and quantify phytochemicals. The highest lutein accumulation occurred 7 days after S 120 mg/L (178%) and Se 40 mg/L (199%) treatments in Red Russian and Dwarf Green kale sprouts, respectively. MeJA treatment decreased the level of most phenolic levels, except for kaempferol and quercetin, where increases were higher than 70% for both varieties when treated with MeJA 25 µM. The most effective treatment for glucosinolate accumulation was S 120 mg/L in the Red Russian kale variety at 7 days of germination, increasing glucoraphanin (262.4%), glucoerucin (510.8%), 4-methoxy-glucobrassicin (430.7%), and glucoiberin (1150%). Results show that kales treated with Se, S, and MeJA could be used as a functional food for fresh consumption or as raw materials for different industrial applications.

Effects of Plant Hormones, Metal Ions, Salinity, Sugar, and Chemicals Pollution on Glucosinolate Biosynthesis in Cruciferous Plant

Cruciferous vegetable crops are grown widely around the world, which supply a multitude of health-related micronutrients, phytochemicals, and antioxidant compounds. Glucosinolates (GSLs) are specialized metabolites found widely in cruciferous vegetables, which are not only related to flavor formation but also have anti-cancer, disease-resistance, and insect-resistance properties. The content and components of GSLs in the Cruciferae are not only related to genotypes and environmental factors but also are influenced by hormones, plant growth regulators, and mineral elements. This review discusses the effects of different exogenous substances on the GSL content and composition, and analyzes the molecular mechanism by which these substances regulate the biosynthesis of GSLs. Based on the current research status, future research directions are also proposed.

Effect of Methyl Jasmonate Treatment on Primary and Secondary Metabolites and Antioxidant Capacity of the Substrate and Hydroponically Grown Chinese Chives

Hydroponic culture has become a commercial planting model for leafy vegetables, herbs, and other plants with medicinal value. Methyl jasmonate (MeJA) is involved in primary and secondary plant metabolism; moreover, it regulates plant bioactive compounds and enhances the nutritional and medicinal value of plants. We performed targeted metabolomic analysis of the primary and secondary metabolites in substrate-grown and hydroponic Chinese chive leaves sprayed with MeJA (0, 300, 500, and 800 μM). Using ultra-performance liquid chromatography (UPLC), UPLC tandem mass spectrometry, and chemometric tools, and analyzed the antioxidant activity of these plants. We identified the biomarkers of amino acids (serine, proline, lysine, and arginine) and phenolic compounds (4-coumaric acid and protocatechuic acid) using chemometric tools to distinguish between substrate-grown and hydroponic Chinese chives treated with MeJA. MeJA (500 μM) treatment significantly increased the total sugar and amino acid (essential and non-essential amino acids and sulfur-containing amino acids) contents of hydroponically grown Chinese chives. However, the changes in total sugar and amino acid contents in Chinese chive grown in substrates showed the opposite trend. The organic acid content of hydroponically grown Chinese chives treated with MeJA decreased significantly, whereas that of substrate-grown plants treated with 300 μM MeJA increased significantly. Further, MeJA treatment significantly increased the phenolic content of substrate-grown Chinese chives. Treatment with 800 μM MeJA significantly increased the carotenoid content of substrate-grown Chinese chives and the phenolic content of hydroponic Chinese chives. In addition, the 500 μM MeJA treatment significantly increased the antioxidant activity of Chinese chives in both substrate-grown and hydroponic cultures, and promoted the accumulation of nutrients and bioactive substances. This treatment also improved the flavor quality of these plants and their nutritional and medicinal value. Thus, the results suggested that MeJA-treated plants could be used as value-added horticultural products.

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.