Increased fructose 1,6-bisphosphate aldolase in plastids enhances growth and photosynthesis of tobacco plants

• Published in: Journal of experimental botany 2012-05, Vol.63 (8), p.3001-3009
• Main Authors: Uematsu, Kimio, Suzuki, Nobuaki, Iwamae, Tomoko, Inui, Masayuki, Yukawa, Hideaki
• Format: Article
• Language: English
• Subjects: Arabidopsis - drug effects; Arabidopsis - enzymology; Arabidopsis Proteins - metabolism; Biological and medical sciences; Biomass; Calvin cycle; Carbon dioxide; Carbon Dioxide - pharmacology; Chloroplasts; Enzymes; Fructose-Bisphosphate Aldolase - metabolism; Fundamental and applied biological sciences. Psychology; Leaves; Nicotiana - drug effects; Nicotiana - genetics; Nicotiana - growth & development; Nicotiana - physiology; Photosynthesis; Photosynthesis - drug effects; Photosynthesis - physiology; Plant growth; Plant physiology and development; Plants; Plants, Genetically Modified; Plastids; Plastids - drug effects; Plastids - enzymology; RESEARCH PAPER; Transformation, Genetic - drug effects; Transgenic plants
• ISSN: 0022-0957; 1460-2431
• DOI: 10.1093/jxb/ers004

The Calvin cycle is the initial pathway of photosynthetic carbon fixation, and several of its reaction steps are suggested to exert rate-limiting influence on the growth of higher plants. Plastid fructose 1,6-bisphosphate aldolase (aldolase, EC 4.1.2.13) is one of the nonregulated enzymes comprising the Calvin cycle and is predicted to have the potential to control photosynthetic carbon flux through the cycle. In order to investigate the effect of overexpression of aldolase, this study generated transgenic tobacco (Nicotiana tabacumL. cv Xanthi) expressingArabidopsisplastid aldolase. Resultant transgenic plants with 1.4–1.9-fold higher aldolase activities than those of wild-type plants showed enhanced growth, culminating in increased biomass, particularly under high CO₂ concentration (700 ppm) where the increase reached 2.2-fold relative to wild-type plants. This increase was associated with a 1.5-fold elevation of photosynthetic CO₂ fixation in the transgenic plants. The increased plastid aldolase resulted in a decrease in 3-phosphoglycerate and an increase in ribulose 1,5-bisphosphate and its immediate precursors in the Calvin cycle, but no significant changes in the activities of ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) or other major enzymes of carbon assimilation. Taken together, these results suggest that aldolase overexpression stimulates ribulose 1,5-bisphosphate regeneration and promotes CO₂ fixation. It was concluded that increased photosynthetic rate was responsible for enhanced growth and biomass yields of aldolase-overexpressing plants.