Effects of Postharvest Ethanol Treatment on the Gene Expression of Ethylene Biosynthetic Enzymes and Ripening-Related Transcription Factors in Banana Fruit

Postharvest ethanol treatment affects the ripening and senescence of horticultural crops. In banana fruit, some reports have found it to inhibit while another report found it to promote. The effects of ethanol treatment on fruit ripening seem to depend on a number of factors, including the mode of application and the duration of exposure. We treated mature green fruit with ethanol vapor by placing the fruit, along with ethanol pads, in a perforated polyethylene bag. The ethanol treatment promoted ripening in this way. To clarify the promotion mechanism, we investigated the effects of ethanol treatment on gene expression of ethylene biosynthetic enzymes, including MaACO1, MaACO2, MaACS1, and MaACS2, and ripening-related transcription factors, including MaMADS1, MaMADS2, and MaMADS7, in the pulp and peel of banana fruit. Overall, the color score was promoted by ethanol treatment, and changes in the gene expression in ethanol-treated fruit in each color score were similar to those in the control fruit, except for MaACS1 in the pulp. These results might support the hypothesis that ethanol essentially could induce the gene expression of ripening-related transcription factors acting upstream of the ethylene-mediated ripening control, resulting in ripened fruit.