Abstract
Banana (Musa AAA group) is one of the most consumed fruits in the world due to its flavor and nutritional value. As a typical climacteric fruit, banana responds to ethylene treatment, which induces rapid changes of color, flavor (aroma and taste), sweetness and nutritional composition. It has also been reported that ripening bananas at temperatures above 24 °C inhibits chlorophyll breakdown and color formation but increases the rate of senescence. To gain fundamental knowledge about the effects of high temperature and ethylene on banana ripening, a quantitative proteomic study employing multiplex peptide stable isotope dimethyl labeling was conducted. In this study, green (immature) untreated banana fruit were subjected to treatment with 10 μL L−1 of ethylene for 24 h. After ethylene treatment, treated and untreated fruit were stored at 20 or 30 °C for 24 h. Fruit peel tissues were then sampled after 0 and 1 day of storage, and peel color and chlorophyll fluorescence were evaluated. Quantitative proteomic analysis was conducted on the fruit peels after 1 day of storage. In total, 413 common proteins were identified and quantified from two biological replicates. Among these proteins, 91 changed significantly in response to ethylene and high-temperature treatments. Cluster analysis on these 91 proteins identified 7 groups of changed proteins. Ethylene treatment and storage at 20 °C induced 40 proteins that are correlated with pathogen resistance, cell wall metabolism, ethylene biosynthesis, allergens and ribosomal proteins, and it repressed 36 proteins that are associated with fatty acid and lipid metabolism, redox–oxidative responses, and protein biosynthesis and modification. Ethylene treatment and storage at 30 °C induced 32 proteins, which were mainly similar to those in group 1 but also included 8 proteins in group 3 (identified as chitinase, cinnamyl alcohol dehydrogenase 1, cysteine synthase, villin-2, leucine-transfer RNA ligase, CP47 protein and calmodulin) and repressed 43 proteins in 4 groups (groups 4–7), of which 6 were associated with photosynthesis II oxygen-evolving protein, the photosynthesis I reaction center, sugar metabolism, the redox–oxidative system and fatty acid metabolism. Differences in the response to ethylene and holding temperature at 30 °C were also revealed and have been discussed. The identities and quantities of the proteins found were linked with quality changes. This study demonstrates that ethylene and high temperature influence banana fruit ripening and senescence at the proteomic level and reveals the mechanisms by which high temperature accelerates banana fruit ripening.
Highlights
Banana (Musa acuminate, AAA group) is among the most popular fruits worldwide due to its attractive color, flavor, sweetness and texture
Banana fruit are typically harvested at the green mature stage and shipped to wholesale markets, where they are treated with ethylene to stimulate fruit ripening; this treatment results in a rapid color change from green to yellow and the development of a ‘fruity’ flavor when stored at 16–24 °C.2
Was observed 4 days after ethylene treatment and hightemperature storage at 30 °C; the hue angle remained 4105° compared with o 96° for fruit stored at 20 °C
Summary
Banana (Musa acuminate, AAA group) is among the most popular fruits worldwide due to its attractive color, flavor, sweetness and texture. The banana is a typical climacteric fruit that produces a significant burst of autocatalytic ethylene and respiration at the onset of ripening, followed by changes in color, firmness and flavor.[1] Banana fruit are typically harvested at the green mature stage and shipped to wholesale markets, where they are treated with ethylene to stimulate fruit ripening; this treatment results in a rapid color change from green to yellow and the development of a ‘fruity’ flavor when stored at 16–24 °C.2. The normal de-greening process can be interrupted if the fruit are stored at temperatures above 24 °C. Under this condition, fruit soften normally but remain green, yielding ‘green ripe’ bananas.[3,4,5] This response of banana fruit to high postharvest temperatures, which results in the failure of proper peel color to develop, causes significant economic loss for the banana industry
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