Table 1.
Representative examples of the beneficial effects triggered by exogenous molecules with signaling properties (melatonin, H2O2, and NO) in fruits to extend postharvest life or to preserve nutritional quality
| Fruit | Concentration | Main effects | Reference |
|---|---|---|---|
| Melatonin | |||
| Peach (Prunus persica L.) |
0.1 mM | Delays postharvest senescence by lowering O2•– and H2O2 accumulation. Higher AA accumulation and increased activity of catalase, SOD, and APX | Gao et al., (2016) |
| Grapevine (Vitis vinifera × labrusca). |
0.2 mM | Stimulates ripening by increasing the levels of ABA, H2O2, and ethylene | Xu et al., (2018) |
| Pear (Pyrus communis L.) |
0.1 mM | Delays postharvest senescence and induces NO accumulation. Higher NOS-like gene expression and enzyme activity. Lower ACS, ACO, PG, and Cel genes expression | Liu et al., (2019) |
| Pear (Pyrus communis L.) |
0.1 mM | Induces anthocyanin accumulation through the H2O2 generated by RBOHF | H. Sun et al., (2021) |
| Sweet cherry (Prunus avium L.) |
0.1 mM | Higher endogenous melatonin accumulation. Higher SOD, CAT, APX, and GR enzyme activity. Higher ascorbate and GSH accumulation. Higher membrane integrity. Lower electrolyte leakage and MDA accumulation. Lower O2•– and H2O2 accumulation | Wang et al., (2019) |
| Sweet cherry (Prunus avium L. var Prime Giant) |
0.01 and 0.1 mM | Delays ripening by modulating the contents of endogenous hormones, mainly ABA and auxin | Tijero et al., (2019) |
| Sweet cherry (Prunus avium L.) |
0.50 and 0.1 mM | Treatment of leaves treated with melatonin improved the antioxidant content of sweet cherry fruit | Xia et al., (2020) |
| Jujube (Ziziphus jujuba Mill.) |
25 µM | Higher APX and GR enzyme activity. Higher ascorbate and GSH accumulation. Lower PG and PME enzymes activity, maintaining firmness | Tang et al., (2020) |
| Pomegranate (Punica granatum L.) |
0.1 mM | Higher NADPH accumulation. Higher APX, GR, G6PDH, 6PGDH, and PAL enzyme activity. Higher AOX gene expression. Higher phenol and anthocyanin accumulation and DPPH-scavenging capacity. Higher AA and GSH accumulation. Lower AAO enzyme activity. | Aghdam et al., (2020a) |
| Mango (Mangifera indica L.) |
0.2 mM | Delays the ripening process. Decreases the contents of H2O2 and MDA in the exocarp of the fruit | Dong et al., (2021) |
| Apple (Malus domestica L. Borkh) |
1 mM | Reduces ethylene production. Increase the activity of catalase, SOD and peroxidase and keeps apple quality during postharvest storage | Onik et al., (2021) |
| Blueberry (Vaccinium corymbosum L.) |
1 mM | Reduces qualitative decay and improves antioxidant system (catalase, SOD, APX, ascorbate, polyphenols, anthocyanins, and flavonoids) during cold storage | Magri and Petriccione, (2022) |
| Kiwifruit (Actinidia chinensis) |
0.1 mM | Palliates chilling injury during cold postharvest storage by inhibition of lignin metabolism and increasing the activity of antioxidant enzymes and the content of soluble antioxidants (ascorbate and GSH) | Jiao et al., (2022) |
| Tomato (Solanum lycopersicum) |
0.5 mM | Promotes ripening of postharvest fruit through DNA methylation of ethylene-signalling genes | Shan et al., (2022) |
| H 2 O 2 | |||
| Melon (Cucumis melo L.) |
20 mM | Treatment of melon plants increases the soluble sugar content in leaves and fruits, thus improving the fruit quality. Increases photosynthetic activity and the activities of chloroplastic and cytosolic fructose-1,6-bisphosphatase, sucrose phosphate synthase, and invertases | Ozaki et al., (2009) |
| Longan (Dimocarpus longan Lour) |
1.96 mM | Increases the activities of pulp PLD, lipase, and LOX. Destroys longan pulp membrane structure and increases cell membrane permeability | Lin et al., (2019) |
| Guava (Psidium guajava L.) |
250 mM | Reduces enzymatic browning of freshly cut fruit by reducing PPO and POD activities. Stimulates the peroxiredoxin/thioredoxin system | Chumyam et al., (2019) |
| Kyoho grape (Vitis vinifera × Vitis labrusca) |
300 mM | Promotes early ripening. Affects the gene expression of HSP, GDSL, XTH, and CAB1, involved in oxidative stress, cell wall deacetylation, cell wall degradation, and photosynthesis, respectively. | Guo et al., (2020) |
| Mango (Mangifera indica L.) |
20 mM | Treated mango plants have fruits with a higher content of total sugar, phenol, and carotenoids | Mostafa, (2021) |
| Tomato (Solanum lycopersicum L. cv. Verty F1) |
100 mM | Increases tomato fruit firmness, decreases water-soluble pectin and expression of cell-wall-related genes, polygalacturonase, and pectate lyase. Maintains morphological and biochemical quality of tomato fruits during postharvest storage | Torun and Uluisik, (2022) |
| NO | |||
| Strawberry (Fragaria × ananassa Duch.) |
5 µM sodium nitroprusside solution | Extends postharvest life | Wills et al., (2007); Zhu and Zhou, (2007) |
| Peach fruit (Prunus persica L. cv. Xiahui 6) |
10 ppm NO gas | Delays the ripening process. Affects sucrose metabolism by changing the expression of related genes | Han et al., (2018) |
| Jujube (Ziziphus jujuba Mill.) |
20 ppm NO gas | Retards cell wall degradation | Zhao et al., (2019) |
| Sweet pepper (Capsicum annuum L. cv. Melchor) |
5 ppm NO gas | Delays fruit ripening. Increases ascorbate content, protein nitration, and S-nitrosation. Decreases catalase and APX activities | Rodríguez-Ruiz et al., (2017); González-Gordo et al., (2019) |
| Tomato (Solanum lycopersicum L. cv. ‘Micro-Tom’) |
300 ppm NO gas | Promotes ascorbate biosynthesis and intensifies protein S-nitrosation and nitration. Affects carotenoid, tocopherol, and flavonoid metabolism | Zuccarelli et al., (2021) |
| Melon (Cucumis melo L.) |
100 ppm NO gas | Enhances postharvest disease resistance to the fungus Alternaria alternata by postponing ethylene biosynthesis | Wei et al., (2021) |
AA, ascorbic acid; AAO, ascorbic acid oxidase; AOX, alternative oxidase; ABA, abscisic acid; ACS, 1-aminocyclopropane-1-carboxylic acid (ACC) synthase; ACO, ACC oxidase; APX, ascorbate peroxidase; CAB1, chlorophyll a-b binding protein; CAT, catalase; Cel, cellulose; DPPH, 2,2-diphenyl-1-picrylhydrazyl; GDSL, GDSL-motif esterase/lipase; G6PDH, glucose-6-phosphate dehydrogenase; GR, glutathione reductase; GSH, reduced glutathione; HSP, heat shock protein; LOX, lipoxygenase; MDA, malondialdehyde; NOS, NO synthase; PG, polygalacturonase; 6PGDH, 6-phosphogluconate dehydrogenase; PLD, phospholipase D; POD, peroxidase; PPO, polyphenol oxidase; RBOHF, respiratory burst oxidase homolog F; SOD, superoxide dismutase; XTH, xyloglucan endotransglucosylase/hydrolase.