BTH treatment caused physiological, biochemical and proteomic changes of muskmelon (Cucumis melo L.) fruit during ripening.

Benzo-(1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester (BTH) is a chemical plant elicitor capable of inducing disease resistance in many crops. In this study, the climacteric fruit muskmelon (cv. Yujinxiang) was treated with BTH at 0.1g/L for assaying the changes in physiology, biochemistry and protein profile during ripening. The results showed that BTH treatment enhanced respiration rate, while reduced titratable acid content and retarded the decline of fruit firmness and ascorbic acid content. Ethylene production increased after BTH treatment at early stages of ripening, but decreased after 6days of treatment. Of the detected protein spots separated by means of 2-DE, 69 spots changed in abundance significantly after BTH treatment. Fifty-two spots out of 69 were identified using MALDI-TOF/TOF by blasting against NCBInr database. Functional classification revealed that the protein species identified were related to defense and stress responses, protein synthesis, destination and storage, energy metabolism, primary metabolism, cell structure, secondary metabolism, signal transduction and transporters. This study demonstrates an overview of major physiological, biochemical and proteomic changes in muskmelon fruit during ripening after BTH treatment and provides potentially useful information for maintaining fruit quality and delaying the ripening and senescence process. BIOLOGICAL SIGNIFICANCE: The study offers new proteomic evidences for elucidating the regulatory mechanism of muskmelon fruit ripening by BTH treatment at proteomic level, and provides a valuable reference for further research on the relationship between fruit quality and induction disease resistance in BTH-treated fruits.