PINEAPPLE SUGAR METABOLISM AND ACCUMULATION DURING FRUIT DEVELOPMENT

Developmental changes in pineapple fruit sugar accumulation were determined for the cultivars ‘Yellow Mauritius’ and ‘Tainung 11’. The concentrations of sucrose, glucose, fructose and the activity of sucrose-metabolizing enzymes, including acid invertase (AI), neutral invertase (NI), sucrose synthase (SS) and sucrose phosphate synthase (SPS) during fruit development were measured and the correlation between sugar accumulation and enzyme activity was systematically analysed. Results showed that the patterns of sugar accumulation for ‘Yellow Mauritius’ and ‘Tainung 11’ were similar with sugar accumulation in both cultivars being very slow during the first stage of fruit development. Sucrose accumulated sharply during the ripe stage, while the concentrations of fructose and glucose reduced slightly. The correlations between the sucrose concentration and the activities of SS and SPS were significant or highly significant in both cultivars while the concentration of sucrose presented a highly significant negative correlation with NI activities in both cultivars. The correlation between sucrose concentration and AI activity was significantly different between the two cultivars.