Plant Physiol, November 1999, Vol. 121, pp. 957-964
The Effect of Elevated Concentrations of Fructose
2,6-Bisphosphate on Carbon Metabolism during Deacidification
in the Crassulacean Acid Metabolism Plant Kalanchöe
daigremontiana 1
Mark R.
Truesdale,
Otto
Toldi,2 and
Peter
Scott*
School of Biological Sciences, University of Sussex, Falmer,
Brighton BN1 9QG, United Kingdom
In
C3 plants, the metabolite fructose 2,6-bisphosphate (Fru
2,6-P2) has an important role in the regulation of carbon
partitioning during photosynthesis. To investigate the impact of Fru
2,6-P2 on carbon metabolism during Crassulacean acid
metabolism (CAM), we have developed an Agrobacterium
tumefaciens-mediated transformation system in order to alter
genetically the obligate CAM plant Kalanchöe daigremontiana. To our knowledge, this is the first report to use genetic manipulation of a CAM species to increase our understanding of this important form of plant metabolism. Transgenic plants were
generated containing a modified rat liver 6-phosphofructo-2-kinase gene. In the plants analyzed the activity of 6-phosphofructo-2-kinase ranged from 175% to 198% of that observed in wild-type plants, resulting in Fru 2,6-P2 concentrations that were 228% to
350% of wild-type plants after 2 h of illumination. A range of
metabolic measurements were made on these transgenic plants to
investigate the possible roles of Fru 2,6-P2 during Suc,
starch, and malic acid metabolism across the deacidification period of
CAM. The results suggest that Fru 2,6-P2 plays a major role
in regulating partitioning between Suc and starch synthesis during
photosynthesis. However, alterations in Fru 2,6-P2 levels
had little effect on malate mobilization during CAM fluxes.
1
This work was supported by funding from the
Biotechnology and Biological Science Research Council and The Royal Society.
2
Present address: Agricultural Biotechnology
Centre, P.O. Box 411, H-2101 Gödöllö, Hungary.
*
Corresponding author; e-mail P.B.Scott{at}sussex.ac.uk; fax
44-1273-678433.
© 1999 American Society of Plant Physiologists
