Effect of Methyl Jasmonate on Pericarp Browning of Postharvest Lychees

Abstract

The application of methyl jasmonate (MJ) for the control of pericarp browning of harvested lychees in relation to the levels of anthocyanins and (–)‐epicatechin was investigated. Lychees were dipped for 3 min in 0.6 µg/L MJ + 0.05% Sportak, 1 µg/L MJ + 0.05% Sportak, 5 µg/L MJ + 0.05% Sportak, 25 µg/L MJ + 0.05% Sportak or 0.05% Sportak (control). In this study, contents of anthocyanins (–)‐epicatechin and lipofuscin‐like substance, and browning index of harvested lychees during storage were determined. The activities of phenylalanine ammonia lyase (PAL), polyphenol oxidase and peroxidase were also measured. The treatment with MJ significantly maintained the contents of anthocyanins and (–)‐epicatechin, delayed the accumulation of lipofuscin‐like substance and extended the shelf life of lychees. Furthermore, MJ treatment increased PAL activity, which can account for the maintenance of anthocyanin or (–)‐epicatechin content. After these treatments, 1 µg/L MJ was effective in inhibiting pericarp browning and in maintaining the contents of anthocyanins and (–)‐epicatechin of lychees. Thus, it is suggested that maintenance of anthocyanin or (–)‐epicatechin contents could be an important factor for controlling pericarp browning of lychees during storage. PRACTICAL APPLICATIONS Lychees are highly perishable after harvest because of rapid skin browning as a result of anthocyanin degradation and (–)‐epicatechin oxidation by polyphenol oxidase or peroxidase in the presence of peroxides, and the subsequent accumulation of lipofuscin‐like substance, a final product of the autooxidation of lipid hydroperoxides, malondialdehydes and proteins of cells. This study exhibited that treatment with 1 µg/L methyl jasmonate (MJ) inhibited significantly the degradation of anthocyanins and the oxidation of (–)‐epicatechin, and delayed significantly the accumulation of lipofuscin‐like substance and pericarp browning of lychees. Therefore, application of MJ could be an important strategy to extend storage life and maintain the quality of harvested lychees based on the maintenance of anthocyanin or (–)‐epicatechin content.

Time of methyl jasmonate application influences the development of ‘Cripps Pink’ apple fruit colour

“…The MJ application resulted in increased synthesis of co‐pigments in the apple fruit skin which ultimately enhanced the development of red blush on the surface of apple fruit at commercial harvest. Recently, inhibition of pericarp browning by maintaining the endogenous level of anthocyanins and epicatechin has been found in MJ‐treated lychee fruit, which also supports our hypothesis. However, the exact mechanism through which MJ regulates the synthesis of anthocyanins and other co‐pigments warrants to be investigated.…”

“…Jasmonic acid (JA) and its methyl ester, methyl jasmonate (MJ) (both are collectively known as jasmonates), are well known to regulate chlorophyll degradation in a variety of fruits such as mango, papaya, lychee and apple . Earlier, exogenous application of MJ has been reported to accelerate de‐greening in apple fruit in a concentration and developmental‐stage‐dependent fashion , .…”

Elicitors: A Tool for Improving Fruit Phenolic Content

“…It has similar activity to JA in plants and so is able to activate the enzymes responsible for the biosynthesis of polyphenols, such as the PAL enzyme (see Figure 1). The activation of PAL following postharvest application of the elicitor has been confirmed in many studies in fruits such as lychees [72], peaches [73], apples, plums, table grapes, strawberries [74] with a subsequent increase of total phenols. The activation of CHS, STS, UDP glucose: flavonoid-O-transferase (UPGT), proteinase inhibitors and chitinase gene expression has also been reported in pre-harvest treatments of grapevine with MeJ.…”

Methyl jasmonate affects phenolic metabolism and gene expression in blueberry (Vaccinium corymbosum)

“…The lower level of catechin is a possible effect of the substrate competition between leucoanthocyanidin reductase (LAR), which catalyzes catechin biosynthesis, and ANS, responsible for the production of anthocyanins which are the immediate precursors for epicatechin synthesis. Epicatechin levels were reported to be positively affected by MeJa in lychees pericarp during post‐harvest (Yang et al ), whereas no effect was recorded in apple fruit (Rudell and Mattheis ). Epicatechin is the monomeric unit forming procyanidin B2, which was particularly abundant in our blueberry samples.…”