Active hexose uptake in Lemna gibba G1 |
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Authors: | C I Ullrich-Eberius A Novacky U Lüttge |
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Institution: | (1) Institut für Botanik der Technischen Hochschule, Schnittspahnstr. 3-5, D-6100 Darmstadt, Federal Republic of Germany;(2) Department of Plant Pathology, University of Missouri, Waters Hall, 65201 Columbia, MO, USA |
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Abstract: | Growth of autotrophically growing duck-weeds (Lemna gibba L., G1) was stimulated by sucrose. The rate of respiration increased when plants had been grown on sucrose (8.7 mol O2 g-1 fresh weight (FW) h-1) and was reduced after growth without sucrose in the dark or under longday conditions (2.5 mol O2 g-1 FW h-1). Photosynthesis was induced already by low light intensities (0.1 klx).Short-time application of glucose or sucrose stimulated respiration in proportion to the hexose uptake rate. Sucrose is probably not taken up as the disaccharide. The transported sugar species after addition of sucrose are its hexose moieties produced by the high activity of the cell wall invertase. Fructose stimulated to a lesser extent; mannitol induced no enhancement; 2-deoxyglucose slightly inhibited O2 uptake. After mild carbon starvation of the plants the uptake of glucose and 3-O-methylglucose proceeded without any lag phase, with similar saturation kinetics in both cases. The initial uptake rate at substrate saturation was 2.6 mol glucose g-1 FW h-1 in the dark. Light stimulated hexose uptake by 2 to 3 times. The results show that Lemna gibba has an energy-dependent constitutive system for hexose uptake.Abbreviation FW
fresh weight
- LD
long day
- SD
short day |
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Keywords: | Hexose uptake Invertase Lemna Photosynthesis Respiration |
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