PARENT SESSION
Plenary Lectures 5
Friday September 3rd, 2004 3:30 PM Room 210A

Altering plant photosynthesis through Rubisco engineering. Spencer Whitney^*,1, T Andrews¹, ¹ Molecular Plant Physiology group, Research School of Biological Sciences, Canberra, Australia

ABSTRACT- Over the last decade, efforts to manipulate the photosynthetic CO₂-fixing enzyme, Rubisco, in planta by plastome-transformation technology have advanced considerably¹. Rubisco's catalytic properties have a profound impact on the efficiency of the photosynthetic process making it an obvious target for manipulation. Its properties have a central role in determining how much light energy plants must harvest to acquire a given amount of carbon, how much fertiliser nutrient must be invested in the photosynthetic machinery, and how much water vapour must be lost in exchange for CO₂. The surgical precision of the homologous-recombination mechanism that enables plastome manipulation provides an excellent tool for testing our knowledge, and our predictions, about Rubisco biology. Already, site-specific mutagenesis² and total replacement^3,4 of the plastid-encoded Rubisco catalytic large subunit are routine. These manipulations in planta are advantageous as they enable detailed assessment of the effects of the mutation on the protein (that is produced in large abundance) and the physiological consequences for the plant as a whole. Our ongoing plastome-transformation projects seek to address different aspects of Rubisco biology - its catalytic process, ways to control the expression of Rubisco transgenes, the folding and assembly of Rubisco subunits in the chloroplast, and the regulation of the introduced enzyme. An overview of the research will be presented. 1) Andrews, T. J. and S. M. Whitney, Arch. of Biochem. and Biophys. 414 (2003) 159-169. 2) S. M. Whitney, S. von Caemmerer, G. S. Hudson, T. J. Andrews, Plant Physiol. 121 (1999) 579-588. 3) I. Kanevski, P. Maliga, D. F. Rhoades, S. Gutteridge, Plant Physiol. 119 (1999) 133-141. 4) S. M. Whitney, T. J. Andrews, Proc. Natl Acad. Sci. USA 98 (2001) 14738-14743.

KEY WORDS: rubisco