Melatonin Preserves the Postharvest Quality of Cut Roses through Enhancing the Antioxidant System

Post-harvest evaluation of the effect of foliar and edaphic applications of silicon in pre-harvest of rose cv. 'Brighton'

The longevity of the rose stem is often affected by the rate of respiration and the evolution in ethylene production, which also favors the development of Botrytis. Silicon is involved in plant defense, and its application could be a strategy to improve disease control. This research evaluated the effect of foliar and edaphic applications of silicon on the life of the Brighton rose using three sources of liquid silicon applied every 2 weeks in three foliar and edaphic conditions and one control. After harvest, the fresh mass loss, ethylene concentration, O2 consumption and CO2 evolution were measured. The number of fallen petals was counted, and the severity of the Botrytis infection was evaluated. The biomass loss of the floral stem was analyzed with profile analysis. For the evaluation of the change in values of O2, CO2 and ethylene, a multivariate semiparametric analysis of variance analysis was used and the generalized estimating equation methodology for the longitudinal binary response of severity. It was found that the soil treatment with lower potassium and soluble silicon was associated with a decrease in ethylene concentration as well as also turned out to be the one that best controlled Botrytis in post-harvest.

Eco-friendly extension of postharvest longevity in Alstroemeria cut flowers using melatonin and putrescine treatments

Postharvest longevity is the most important factor concerning the commercial value of cut flowers. Alstroemeria 'Amatista' is one of the most valued species for its ornamental appeal and it has been often reported to suffer from premature senescence. The present study was undertaken to establish the efficacy of melatonin (100 and 200 μM) and putrescine (1.5 and 3 mM) as enviro-friendly compounds applied into the vase solution in extending the vase life of cut flowers of Alstroemeria by assessing different physiological parameters. Results showed that melatonin at 100 and 200 μM and putrescine at 1.5 mM significantly extended the flower vase life from 12 to 13 days (control) to 20-21 days. More precisely, both melatonin and putrescine lowered electrolyte leakage (EL) and increased relative water content (RWC), relative fresh weight (RFW), and relative solution uptake (RSU) of flowers. In addition, both compounds enhanced the total anthocyanin content, phenylalanine ammonia-lyase (PAL) and polyphenol oxidase (PPO) activities, and reduced malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) content, which implies the decline in oxidative stress. These results confirm that both melatonin and putrescine act as effective and environmental-friendly exogenous applications to improve postharvest quality and extend the vase life of Alstroemeria cut flowers. The study provides important information for possible applications in the floriculture industry.

Melatonin induces drought stress tolerance by regulating the physiological mechanisms, antioxidant enzymes, and leaf structural modifications in Rosa centifolia L

Melatonin is considered an effective bio-stimulant that is crucial in managing several abiotic stresses including drought. However, its potential mechanisms against drought stress in fragrant roses are not well understood. Here, we aim to investigate the role of melatonin on Rosa centifolia plants cultivated under drought stress (40 % field capacity) and normal irrigation (80 % field capacity). Plant growth traits, gaseous exchange, antioxidants, osmolytes, oxidative stress, and leaf anatomical attributes were measured. All pots were arranged with a completely randomized design with two-factor factorial setup. Foliar application of melatonin was carried out on the next day of drought treatment and was repeated weekly, while normal watering was regarded as control. Drought stress significantly enhanced oxidative stress markers and reduced growth parameters in water-deficit rose plants. However, melatonin spray (100 μM) produced increased plant height (16 %), flower yield (16 %), petal fresh and dry biomass (7 % and 38 %), total chlorophyll (48 %), contents of carotenoid (54 %), and gaseous exchange traits such as stomatal conductance (25 %), photosynthetic rate (91 %), and transpiration rate (3 %), in water-deficient plants. Likewise, the accretion of catalase, superoxide dismutase, soluble protein, proline, and glycine betaine contents was recorded by 22 %, 45 %, 58 %, 7 %, and 6 %, respectively, in drought-stressed plants, due to melatonin treatment. Increment of oxidative stress indicators i.e. malondialdehyde (-37 %) and hydrogen peroxide (-27 %) was diminished by melatonin triggered by drought stress. Furthermore, leaf cortex (51 %), vascular bundle area (76 %), palisade cell area (59 %), and lamina thickness (42 %) were remarkably increased with melatonin foliar sprays in water-deficit plants. The results of this study recommend that melatonin is a protective agent against drought stress and has potential application prospects in the rose-producing regions suffering from water deficiency. Future studies should focus on molecular responses of R. centifolia to drought stress to further develop stress alleviation strategies in floricultural crops.

The role of melatonin in delaying senescence and maintaining quality in postharvest horticultural products

The postharvest lifespan of horticultural products is closely related to loss of nutritional quality, accompanied by a rapid decline in shelf life, commercial value, and marketability. Melatonin (MT) application not only maintains quality but also delays senescence in horticultural products. This paper reviews biosynthesis and metabolism of endogenous MT, summarizes significant effects of exogenous MT application on postharvest horticultural products, examines regulatory mechanisms of MT-mediated effects, and provides an integrated review for understanding the positive role of MT in senescence delay and quality maintenance. As a multifunctional molecule, MT coordinates other signal molecules, such as ABA, ETH, JA, SA, NO, and Ca2+, to regulate postharvest ripening and senescence. Several metabolic pathways are involved in regulation of MT during postharvest senescence, including synthesis and signal transduction of plant hormones, redox homeostasis, energy metabolism, carbohydrate metabolism, and degradation of pigment and cell wall components. Moreover, MT regulates expression of genes related to plant hormones, antioxidant systems, energy generation, fruit firmness and colour, membrane integrity, and carbohydrate storage. Consequently, MT could become an emerging and eco-friendly preservative to extend shelf life and maintain postharvest quality of horticultural products.

Exogenous Melatonin Boosts Heat Tolerance in Rosa hybrida via RhCOMT1 Modulation

Rosa hybrida is one the most commonly cultivated ornamental plant of economic importance and faces major challenges under heat stress. Melatonin has been widely shown to regulate plant stress response; however, the exact mechanism involved in heat stress in R. hybrida has yet to be determined. Here, we observed that R. hybrida in vitro plantlets supplemented with melatonin in the culture medium exhibited higher chlorophyll content, relative ion leakage, and fresh weight after 12 d of high-temperature treatment; the optimal concentration was established at 5 mg/L. Using molecular and biochemical techniques, we explored the roles of a melatonin synthase gene RhCOMT1, which expression was influenced by heat stress and melatonin. RhCOMT1 was located in the nuclear-cytoplasmic under ambient conditions, while heat stress translocated the distribution of RhCOMT1 to chloroplasts. Overexpression of RhCOMT1 in rose petal enhanced thermotolerance, and silencing of RhCOMT1 reduced thermotolerance via affect H2O2 content and relative ion leakage. These findings collectively emphasize the pivotal role of melatonin in enhancing thermotolerance to R. hybrida by alleviation of oxidative stress, through modulation of RhCOMT1 expression and location.

Lipopeptides from Bacillus atrophaeus MCM61 and melatonin suppress gray mold-induced oxidative stress in cut roses (Rosa hybrida L.) and improve vase life

Application of melatonin and lipopeptides (LPs) derived from Bacillus strains is considered an efficient strategy to control plant diseases at both pre and postharvest stages. However, the combined application of melatonin and LPs has not been studied yet. Therefore, the present study presents the synergistic effect of melatonin and LPs produced by Bacillus atrophaeus strain MCM61 against gray mold disease and its impact on quality parameters and vase life of cut roses. The stems of cut roses along with flowers were dipped in the melatonin solution at concentration (0, 0.2, 0.4, 0.6, and 0.8 mM) and the results indicated that the vase life of flowers treated with the melatonin was enhanced compared to control. Melatonin at 0.6 mM concentration showed the highest vase life of cut roses at day 8. Synergistic treatment with melatonin and LPs of B. atrophaeus MCM61 revealed that MDA and H2O2 content showed the highest decrease in cut roses. Similarly, relative water content, total phenol content, GSH content, and defense enzymes i.e., APX, SOD, PPO, POD, and CAT activities were increased in cut roses treated with co-application of B. atrophaeus MCM61 LPs and melatonin compared to single treatments and control treatment. Furthermore, the longevity of cut roses was also improved in flowers treated with a combined application of MCM61 and melatonin compared to other treatments.

Phytomelatonin: From Intracellular Signaling to Global Horticulture Market

Melatonin (N-acetyl-5-methoxytryptamine), a well-known mammalian hormone, has been having a great relevance in the Plant World in recent years. Many of its physiological actions in plants are leading to possible features of agronomic interest, especially those related to improvements in tolerance to stressors and in the postharvest life of fruits and vegetables. Thus, through the exogenous application of melatonin or by modifying the endogenous biosynthesis of phytomelatonin, some change can be made in the functional levels of melatonin in tissues and their responses. Also, acting in the respective phytomelatonin biosynthesis enzymes, regulating the expression of tryptophan decarboxylase (TDC), tryptamine 5-hydroxylase (T5H), serotonin N-acetyltransferase (SNAT), N-acetylserotonin O-methyltransferase (ASMT), and caffeic acid O-methyltransferase (COMT), and recently the possible action of deacetylases on some intermediates offers promising opportunities for improving fruits and vegetables in postharvest and its marketability. Other regulators/effectors such as different transcription factors, protein kinases, phosphatases, miRNAs, protein-protein interactions, and some gasotransmitters such as nitric oxide or hydrogen sulfide were also considered in an exhaustive vision. Other interesting aspects such as the role of phytomelatonin in autophagic responses, the posttranslational reprogramming by protein-phosphorylation, ubiquitylation, SUMOylation, PARylation, persulfidation, and nitrosylation described in the phytomelatonin-mediated responses were also discussed, including the relationship of phytomelatonin and several plant hormones, for chilling injury and fungal decay alleviating. The current data about the phytomelatonin receptor in plants (CAND2/PMTR1), the effect of UV-B light and cold storage on the postharvest damage are presented and discussed. All this on the focus of a possible new action in the preservation of the quality of fruits and vegetables.

An analysis of conventional and modern packaging approaches for cut flowers: a review article

Fresh-cut flowers are considered to be one of the most delicate and challenging commercial crops. It is important to take into consideration how to minimize loss during storage and transportation when preserving cut flowers. Many impinging (bad effect) forces can interact to shorten the flowers' vase life. In the flower industry, effective methods need to be developed to extend freshly cut flowers' life. Fresh-cut flowers' vase life can be shortened by a variety of interlocking causes. The flower industry must develop new techniques to extend the flowers' vase lifespan. This review provides comprehensive, up-to-date information on classical, modified atmosphere packaging (MAP), and controlled atmosphere packaging (CAP) displays. According to this review, a promising packaging technique for fresh flowers can be achieved through smart packaging. A smart package is one that incorporates new technology to increase its functionality. This combines active packaging, nanotechnology, and intelligence. This technology makes it easier to keep an eye on the environmental variables that exist around the packaged flowers to enhance their quality. This article offers a comprehensive overview of creative flower-saving packaging ideas that reduce flower losses and assist growers in handling more effectively their flower inventory. To guarantee the quality of flowers throughout the marketing chain, innovative packaging techniques and advanced packaging technologies should be adopted to understand various package performances. This will provide the consumer with cut flowers of standard quality. Furthermore, sustainable packaging is achieved with circular packaging. We can significantly reduce packaging waste's environmental impact by designing reused or recyclable packaging.

Preharvest melatonin foliar treatments enhance postharvest longevity of cut tuberose via altering physio-biochemical traits

INTRODUCTION

Melatonin (MLT) is a bioactive molecule involved in the physiological functioning of plants. Reports related to preharvest applications of melatonin on the postharvest performance of cut flowers are not available in the literature.

MATERIALS & METHODS

This study evaluated the effects of different concentrations of exogenous MLT [0 mM (MT0), 0.5 mM (MT1), 0.7 mM (MT2), 1 mM (MT3)] applied preharvest on the physiological characteristics and postharvest performance of cut tuberose, a globally demanded cut flower.

RESULTS & DISCUSSION

The results revealed that all treatments increased postharvest vase life by up to 4 d. The MT1, MT2, and MT3 treatments increased total soluble proteins (TSP) by 25%, 41%, and 17%, soluble sugars (SS) by 21%, 36%, and 33%, an+d postharvest catalase (CAT) activity by 52%, 66%, and 70%, respectively. Malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) decreased in all preharvest treatments by up to 23% and 56%, respectively. Proline concentration decreased in all treatments, particularly MT3 (38%). These findings suggest that preharvest MLT treatment is a promising strategy for improving the postharvest quality of cut tuberose.

The combination of graphene oxide and preservatives can further improve the preservation of cut flowers

It is reported that the use of nanomaterials can extend the vase life of fresh-cut flowers. Graphene oxide (GO) is one of these nanomaterials that aid in promoting water absorption and antioxidation during the preservation of fresh-cut flowers. In this investigation, the three mainstream brands of preservatives commercially available on the market ("Chrysal," "Floralife," and "Long Life") in combination with low concentrations of GO (0.15 mg/L) were used to preserve fresh-cut roses. The results showed that the three brands of preservatives had different degrees of freshness retention. Compared to the preservatives used alone, the combination of low concentrations of GO with the preservatives, especially in the L+GO group (with 0.15 mg/L GO added in the preservative solution of "Long life"), further improved the preservation of cut flowers. L+GO group showed less level of antioxidant enzyme activities, lower ROS accumulation and cell death rate, and higher relative fresh weight than the other groups, implying a better antioxidant and water balance abilities. GO attached to the xylem duct of flower stem, and reduced the blockage of xylem vessels by bacteria, which were determined by SEM (scanning electron microscopy) and FTIR (Fourier transform infrared) analysis. XPS (X-ray photoenergy spectra) analysis results proved that GO could enter the interior of flower stem through xylem duct, and when combined with "Long Life," the anti-oxidation protection ability of GO was enhanced, thus delaying ageing, and greatly extending the vase life of fresh-cut flowers. The study provides new insights into cut flower preservation using GO.