Reduction of chilling injury in stored avocado, grapefruit, and bell pepper by methyl jasmonate

Subjecting some chilling-sensitive commodities to various moderate stresses can cause them to acquire resistance to chilling injury. Jasmonates have been implicated in playing an integral role in the signal transduction cascade that operates in plants to induce responses to stress. Therefore, it was hypothesized that exogenous application of jasmonic acid or methyl jasmonate to chilling-sensitive commodities might replace the moderate stress treatment and reduce their chilling symptoms. To test this hypothesis, three chilling-susceptible fruits, avocado (Persea americana Mill., cvs. Hass, Etinger, and Fuerte), grapefruit (Citrus paradisi cv. Marsh seedless), and red bell pepper (Capsicum annum cv. Maor), were treated with various concentrations of methyl jasmonate prior to 4–10 weeks of storage at 2 °C. Results show that methyl jasmonate dipping (for 30 s) of avocado 'Fuerte' and 'Hass' (2.5 μM), avocado 'Etinger' or grapefruit (10 μM), and red bell pepper fruits (25 μM) significantly reduced both the severity of their chilling injury symptoms and the percentage of injured fruits. Application of methyl jasmonate by gassing for 24 h was similarly effective. In avocado 'Etinger', methyl jasmonate dipping was effective in alleviating chilling injury either after immediate storage at 2 °C or after the fruits had been held for 1 day at 20 °C prior to their storage at 2 °C. The results suggest that methyl jasmonate, which is receiving renewed biological interest as a potentially important signaling molecule in plants, might mediate the plant's natural response to chilling stress, and by its application might provide a simple means to reduce chilling injuries in chilling-susceptible commodities. Keywords: chilling injury, methyl jasmonate, postharvest treatment, stored fruits.