Abstract: The objective of this study was to investigate the effect of postharvest treatment with the plant resistance inducer benzo(1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester (BTH) on the activity of l-deoxy-D-xylulose-5-phosphate reductoisomerase (DXR) and aroma-active monoterpenes in muskmelon (Cucumis melo L. cv. Yujinxiang) and to analyze the correlation between DXR activity and the release of aroma-active monoterpenes. Changes in DXR activity, involved in the metabolic pathway of aroma-active monoterpenes and monoterpene composition were monitored during postharvest storage at room temperature. The results showed that a total of nine aroma-active monoterpene components were detected in the samples during the storage period. Eight of these compounds were positively correlated with DXR activity. Upon postharvest BTH treatment, DXR activity and the release of monoterpenes were inhibited accompanied by delayed peak time of DXR activity as well as altered release pattern of aroma-active monoterpenes and correlation with DXR activity. Compared with the CC group (distilled water immersion), DXR activity in the rind and pulp of BTH-treated melon was reduced by 19.48% and 25.49%, respectively. The effect of distilled water immersion on DXR activity and the release of aroma-active monoterpenes was irregular although it increased the peak of DXR activity. From these findings, it is clear that postharvest BTH treatment can inhibit DXR activity, delay the peak time of DXR activity and affect the release of aromaactive monoterpenes and its correlation with DXR activity.

Key words: benzo(1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester, l-deoxy-D-xylulose-5-phosphate reductoisomerase, aroma-active monoterpenes