Abstract
Plant cells live and grow in a manner totally dependent upon sugars. Externally applied sugars support the long-term growth of cells in the tissue and/or cell cultures of various plant species. However, mannose (Man) is not usable as external carbon source by many plants. We compared soluble sugar compositions and metabolisms in various types of azuki-bean cells cultivated in the presence or absence of Man. We found that the heterotrophic cells commonly required Suc and wall polysaccharide syntheses via sugar-phosphates and sugar-nucleotides pathways for their growth activities. Also the levels of sugar-phosphates and the isomerase activities appeared important for cell ability to use uncommon sugars as external carbon sources. Callus cells can utilize Man as a sole carbon-source on agar media but not in liquid cell-suspension culture, suggesting an important timing or balance between induction of PMI enzyme and temporal accumulation of M-6-P in cells.
