Changes in sugar metabolism enzyme activities in cultivars of two pumpkin species (Cucurbita maxima and C. moschata) during fruit development
2004
Tateishi, A. (Nihon Univ., Tokyo (Japan)) | Nakayama, T. | Isobe, K. | Nomura, K. | Watanabe, K. | Inoue, H.
Summary Sugar accumulation and sugar metabolism enzyme activities were measured in two distinct pumpkin cultivars, 'Miyako' (C. maxima) and 'Hayato' (C. moschata) during fruit development. Sugar accumulation levels in the fruits were different between these cultivars. At the harvesting stage, more glucose and fructose were accumulated in 'Hayato' than in 'Miyako'. Sucrose content was low in young fruit when its catabolic enzyme activities were highest. The accumulation of sucrose with fruit development in both cultivars coincided with increasing sucrose phosphate synthase (SPS) activity and decreasing catabolic enzyme activities. The amount of sucrose content was indistinguishable in both cultivars, whereas, higher SPS activity was observed in 'Hayato'. SPS contributes to sucrose accumulation in the late stage of pumpkin fruit development, but the amount of accumulated sucrose could not be explained solely on SPS activity.
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