Melatonin promotes ripening and improves quality of tomato fruit during postharvest life

Self Cite

165

To better understand the function of melatonin in tomato fruit ripening and quality improvement, a label-free quantitation method was used to investigate the proteins that differ between the control (CK) and 50 μm melatonin treatment (M50) fruits. Proteomics data identified 241 proteins that were significantly influenced by melatonin. These proteins were involved in several ripening-related pathways, including cell wall metabolism, oxidative phosphorylation, carbohydrate, and fatty acid metabolism. Moreover, the application of exogenous melatonin increased eight proteins that are related to anthocyanin accumulation during fruit ripening. Additionally, the affected protein levels correlated with the corresponding gene transcript levels. Further, the total anthocyanin content from M50 increased by 52%, 48%, and 50% at 5, 8, and 13 DAT (day after melatonin treatment), respectively. The melatonin-mediated promotion of fruit ripening and quality might be due to the altered proteins involved in processes associated with ripening. In this work, we indicated that a senescence-related protein was downregulated in the M50 fruit, while a cell apoptosis inhibitor (API5) protein was upregulated. In addition, peroxidases (POD9, POD12, peroxidase p7-like) and catalase (CAT3) significantly increased in the M50 fruits. Based on the previous studies and our data, we inferred that melatonin might be positively related to fruit ripening but negatively related to fruit senescence. This research provides insights into the physiological and molecular mechanisms underlying melatonin-mediated fruit ripening as well as the anthocyanin formation process in tomato fruit at the protein concentration level, and we reveal possible candidates for regulation of anthocyanin formation during fruit ripening.

Section: Resultssupporting

confidence: 92%

A label‐free differential proteomics analysis reveals the effect of melatonin on promoting fruit ripening and anthocyanin accumulation upon postharvest in tomato

Sun

Zhang

Wang

et al. 2016

Self Cite

165

“…As more studies become available on melatonin's functional roles in plant growth and development [37][38][39][40], the biosynthetic mechanism of melatonin in plants should be further explored. In this report, we confirmed that the Arabidopsis SNAT homologous gene and its corresponding SNAT protein play a role with COMT to synthesize melatonin in vitro.…”

Section: Discussionmentioning

confidence: 99%

Cloning of Arabidopsis serotonin N‐acetyltransferase and its role with caffeic acid O‐methyltransferase in the biosynthesis of melatonin in vitro despite their different subcellular localizations

Lee

Byeon

Lee

et al. 2014

119

118

Serotonin N-acetyltransferase (SNAT) is the penultimate enzyme in melatonin biosynthesis. We cloned SNAT from Arabidopsis thaliana (AtSNAT) and functionally characterized this enzyme for the first time from dicotyledonous plants. Similar to rice SNAT, AtSNAT was found to localize to chloroplasts with peak enzyme activity at 45 °C (Km , 309 μm; Vmax , 1400 pmol/min/mg protein). AtSNAT also catalyzed 5-methoxytryptamine (5-MT) into melatonin with high catalytic activity (Km , 51 μm; Vmax , 5300 pmol/min/mg protein). In contrast, Arabidopsis caffeic acid O-methyltransferase (AtCOMT) localized to the cytoplasm. Interestingly, AtCOMT can methylate serotonin into 5-MT with low catalytic activity (Km , 3.396 mm; Vmax , 528 pmol/min/mg protein). These data suggest that serotonin can be converted into either N-acetylserotonin by SNAT or into 5-MT by COMT, after which it is metabolized into melatonin by COMT or SNAT, respectively. To support this hypothesis, serotonin was incubated in the presence of both AtSNAT and AtCOMT enzymes. In addition to melatonin production, the production of major intermediates depended on incubation temperatures; N-acetylserotonin was predominantly produced at high temperatures (45 °C), while low temperatures (37 °C) favored the production of 5-MT. Our results provide biochemical evidence for the presence of a serotonin O-methylation pathway in plant melatonin biosynthesis.

“…A novel study on the effect of exogenous melatonin on ethylene metabolism, postharvest ripening, and the quality of tomato fruit showed that tomatoes treated with 50 μ m melatonin for 2 hr manifested substantial changes in their fruit ripening parameters, such as lycopene levels, fruit softening, flavor, ethylene signaling, and biosynthesis enzymes with respect to untreated tomatoes . Exogenous melatonin slightly increased ethylene generation and further timing of climacteric peak through the upregulation of 1‐aminocyclopropane‐1‐carboxylic acid (ACC) synthase expression.…”

Section: Melatonin As a Plant (Hormone) Regulatormentioning

confidence: 99%

“…Possibly, this opposite effect was due to the differences in the auxin‐mediated response between vegetative and reproductive tissues. Also, exogenous melatonin treatment provoked the upregulation of genes related with lycopene biosynthesis‐, aroma/flavor‐, cell wall structure, and aquaporin in tomatoes, leading to the conclusion that melatonin promotes postharvest tomato fruit ripening through increased ethylene production and signaling . Nevertheless, different effects could appear in vegetative tissues.…”

Section: Melatonin As a Plant (Hormone) Regulatormentioning

confidence: 99%

Functions of melatonin in plants: a review

Arnao

Hernández‐Ruíz

2015

670

507

The number of studies on melatonin in plants has increased significantly in recent years. This molecule, with a large set of functions in animals, has also shown great potential in plant physiology. This review outlines the main functions of melatonin in the physiology of higher plants. Its role as antistress agent against abiotic stressors, such as drought, salinity, low and high ambient temperatures, UV radiation and toxic chemicals, is analyzed. The latest data on their role in plant-pathogen interactions are also discussed. Both abiotic and biotic stresses produce a significant increase in endogenous melatonin levels, indicating its possible role as effector in these situations. The existence of endogenous circadian rhythms in melatonin levels has been demonstrated in some species, and the data, although limited, suggest a central role of this molecule in the day/night cycles in plants. Finally, another aspect that has led to a large volume of research is the involvement of melatonin in aspects of plant development regulation. Although its role as a plant hormone is still far of from being fully established, its involvement in processes such as growth, rhizogenesis, and photosynthesis seems evident. The multiple changes in gene expression caused by melatonin point to its role as a multiregulatory molecule capable of coordinating many aspects of plant development. This last aspect, together with its role as an alleviating-stressor agent, suggests that melatonin is an excellent prospect for crop improvement.