TITLE	Sugar uptake by photomixotrophic soybean suspension cultures1
AUTHOR	H. Emilie Yen Department of Botany, National Chung-Hsing University, Taichung 402, Taiwan, Republic of China Yu-Chi Chen Department of Botany, National Chung-Hsing University, Taichung 402, Taiwan, Republic of China Shi-Kae Yen Department of Botany, National Chung-Hsing University, Taichung 402, Taiwan, Republic of China Jeng-Horng Lin Department of Botany, National Chung-Hsing University, Taichung 402, Taiwan, Republic of China
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ABSTRACT	A photomixotrophic soybean (Glycine max) culture with substantial chlorophyll content was used to study the ability of cells to grow on different carbon sources. With the exception of sorbitol, these photomixotrophic cells were able to grow on media containing 3% starch, or 2% sucrose, maltose, glucose and fructose; and the growth curves and biomass production of hexose- or disaccharide-grown cells were all fairly similar. The highest biomass production was found in the sucrose-grown cells. Levels of soluble protein and total chlorophyll and the Chl a/b ratio were highest in the starch-grown cells. Although the growth curves of sucrose-, glucose-, or fructose-grown cells were quite similar, the abilities of cells grown on one source to utilize various carbon sources were quite distinct. 14C-labelling experiments showed that the highest incorporation rates for sucrose and hexoses all occurred during the logarithmic phase with sucrose-grown cells preferentially taking up sucrose and hexose-grown cells preferentially taking up hexoses. Cells maintained on 3% starch showed an ability to take up both sucrose and hexoses with the highest uptake rate when fed with 14C-glucose. The rate of uptake of sucrose was decreased more than twofold as cells entered the stationary phase, while there was a twofold increase in the activity of extracellular acid invertase (EC 3.2.1.26). The clear correlation between low acid invertase activity and high levels of incorporated radioactivity from 14C-sucrose strongly suggested that intact sucrose is being taken up in sucrose-fed soybean cells during the vigorous growth stage, a stage similar to developing soybean pods.
KEYWORD	Acid invertase; Glycine max; Photomixotrophic suspension culture; Sugar uptake;
ARTICLE INFO	Botanical Bulletin of Academia Sinica, Volume 40 Number 2 April 1999, page 147-152, 6 pages
PUBLISHER	Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan, Republic of China