Abstract
Suspension-cultured cells of azuki bean utilize sucrose and glucose but neither galactose nor mannose. Galactose inhibits sucrose synthesis in cells but mannose appears lacking this effect (Inouhe and Kato 2003). In this study, we compared the possible effects of mannose on growth and sucrose concentration of cells in the liquid and solid cultures. We also determined the phosphomannose isomerase (PMI) activity as a candidate enzyme converting mannose to sucrose via sugar phosphates. Azuki bean cells in liquid medium containing 1% mannose had very slow growth rate and decreased sucrose level. By contrast, the cells inoculated on agar medium containing mannose proliferated actively after a month of nascent period and increased the intracellular sucrose level. We found that the PMI activity in the mannose-adapted cells increased as a function of culture period. However, similar activities were detected in cells grown in sucrose medium. Mannose-adaptation appeared to involve the other enzymatic pathway(s).
