Changes in the sugar content and sucrose metabolizing enzymatic activities of stored green peas were studied.Green pea seeds were removed from their pods, and the pods without seeds or whole peas were stored at 1'C or 20'C.Their sucrose content significantly decreased, especially in seeds without pods stored at 20'C, but the stachyose and verbascose contents increased. Glucose and sucrose were the major components in the pods. The pod sucrose content significantly decreased, especially in pods with seeds stored at 20'C. Sucrose synthase (sucrose synthesis, sucrose cleavage) and invertase activities in the seeds decreased during storage, but sucrose phosphate synthase activity increased after I or 2 days of storage and then decreased. According to these results, we suggest that sucrose might be utilized not only in the synthesis of starch, but also in the synthesis of the raffinose family of oligosaccharides such as stachyose and verbascose.Keywords: oligosaccharide, storage, pea, sucrose phosphate synthase, sucrose synthase, invertaseIn Japan, immature peas and soybeans are used as vegetables. The quality of these green peas and green soybeans immediately changes after harvest. A decrease in sweetness, increase in hardness and decrease in sugar, amino acids and ascorbate content occur. Ito et al ( 1972) demonstrated that sucrose is utilized in starch biosynthesis during storage. Saravitz et a/ ( 1 987) reported that rafnnose and stachyose levels increased during the development of soybean seeds. Matsushita (1968) showed a decrease in sucrose content and increase in starch content during pea seed development.Changes in the sugar and starch content of stored green peas (Ito et al., 1972;Shono et al, 1990Shono et al, , 1996 and stored green soybeans (Iwata & Shirahata, 1979;Shono, 1987;Masuda et al., 1988;Terai et a/., 1995) were also reported, but little is known of the changes in the activities of sucrose metabolizing enzymes and oligosaccharide content during storage.In thls paper, we examined the changes in sugar content and the activities of sucrose metabolizing enzymes in order to elucidate the sucrose metabolism of stored green peas.
Materials and Methods