Soluble Sugar Accumulation and Activity of Related Enzymes During Muskmelon Fruit Development

Abstract Changes in soluble sugar composition of muskmelon ( Cucumis melo L. var. reticulatus Naud.) mesocarp were followed throughout fruit development. Glucose and fructose, in nearly equal amounts, were the predominant sugars detected during the first 24 days after anthesis. Sucrose began to accumulate 24 days after anthesis and was the predominant sugar present in the ripe fruit. A soluble acid invertase (pH optimum 4.0 to 5.0) was detected in mesocarp extracts. Activity of acid invertase was highest in the young fruit and declined with development. Sucrose synthase activity was also detected in mesocarp extracts. Sucrose synthase activity increased between 18 and 24 days after anthesis and thereafter remained constant. Acid invertase and sucrose synthase appeared to be involved in the metabolism of sucrose during muskmelon fruit development.