METHYL JASMONATE IMPROVES QUALITY OF STORED ZUCCHINI SQUASH

A Synergistic Effect Based on the Combination of Melatonin with 1-Methylcyclopropene as a New Strategy to Increase Chilling Tolerance and General Quality in Zucchini Fruit

Zucchini fruit are highly sensitive to low temperatures leading to significant peel depressions, increasing weight loss and making them impossible to be commercialized. In this study the effect on the reduction of chilling injury (CI) assaying different postharvest treatments to cv. Cronos was evaluated. We have compared the application of substances such as 1-methylcyclopropene (1-MCP) with the application of a natural origin compound as melatonin (MT), both with demonstrated activity against CI in different vegetal products. The effects of MT (1 mM) by dipping treatment of 1 h and 1-MCP (2400 ppb) have been evaluated on zucchini fruit during 15 days of storage at 4 °C plus 2 days at 20 °C. Treatments applied independently improved some fruit quality parameters in comparison with control fruit but were not able to manage CI even though they mitigated the impact on several parameters. However, when these two separated strategies were combined, zucchini cold tolerance increased with a synergic trend. This synergic effect affected in general all parameters but specially CI, being also the only lot in which zucchini fruit were most effectively preserved. This is the first evidence in which a clear positive effect on zucchini chilling tolerance has been obtained combining these two different strategies. In this sense, the combined effect of 1-MCP and MT could be a suitable tool to reach high quality standards and increasing shelf life under suboptimal temperatures.

Roles of C-Repeat Binding Factors-Dependent Signaling Pathway in Jasmonates-Mediated Improvement of Chilling Tolerance of Postharvest Horticultural Commodities

C-repeat binding factor- (CBF-) dependent signaling pathway is proposed to be a key responder to low temperature stress in plant. Jasmonates (JAs), the endogenous signal molecules in plant, participate in plant defense against (a)biotic stresses; however, the mechanism has not been fully clarified so far. With the progress made in JAs biopathway, signal transduction, and their relationship with CBF-dependent signaling pathway, our knowledge of the roles of the CBF-dependent signaling pathway in JAs-mediated improvement of chilling tolerance accumulates. In this review, we firstly briefly review the chilling injury (CI) characteristics of postharvest horticultural commodities, then introduce the biopathway and signal transduction of JAs, subsequently summarize the roles of the CBF-dependent signaling pathway under low temperature stress, and finally describe the linkage between JAs signal transduction and the CBF-dependent signaling pathway.

Influence of methyl jasmonate on inducing chilling tolerance in pomegranate fruits (Malas Save)

Susceptibility to chilling injury in pomegranate is the main limiting factors for storage fruits in low temperature. Inducing chilling tolerance make possible to storage fruits in low temperature for long time. In this study effect of different concentrations of methyl jasmonate (8, 16 and 24 microL L(-1)) as comparison with control on inducing chilling tolerance of pomegranate fruits (Malas Save) was investigated. Qualitative attributes of treated fruits was investigated in different times during low temperature storage and also after transferring that to high temperature as a shelf life. The results showed that methyl jasmonate suppressed chilling injury and water loss and preserved external appearance in pomegranate fruits without abnormal effects on internal fruits quality. In general, with increasing methyl jasmonate concentration, fruits chilling injury reduced significantly. The highest chilling injury index was found in control fruits and the lowest one was for 24 microL L(-1) during storage in low temperature and also after placing in high temperature. Furthermore, no significant differences was found between treated and control fruits for internal fruit characteristics at end of storage.

Methyl jasmonate treatments reduce chilling injury and activate the defense response of guava fruits

Tropical fruits cannot be stored at low temperatures due to the chilling injury phenomena. With the goal of reducing the chilling injury, we tested 10(-4) and 10(-5) M of methyl jasmonate (MJ) treatment before the storage of red and white cultivars of guava fruits at 5 degrees C for up to 15 days plus two days at 20 degrees C. Every five days, we evaluated chilling injury index, ion leakage percentage, vitamin C, sugars, total phenols, and the activity of the enzymes lipoxygenase (LOX) and phenylalanine-ammonia lyase (PAL). We found that methyl jasmonate treatments reduce the chilling injury index and the ion leakage percentage. Furthermore, MJ did not affect vitamin C, chlorophyll, and total phenols. MJ increased sugar content, PAL, and LOX activities. We concluded that MJ reduces chilling injury and activates the fruit defense response as indicated by the behavior of total phenols and the increase in sugar content, PAL, and LOX activities.