PARENT SESSION

Symposium S7D Chloroplast factories and transformation
Thursday September 2nd, 2004 2:40 PM-4:40 PM Room 510A
Chair: Dick Sayre
Co-Chair: Pal Maliga

Engineering foreign RUBISCOS in higher plant plastids. Spencer Whitney^*,, John Andrews,

ABSTRACT- The ease by which modified or foreign forms of the CO₂-fixing enzyme, Rubisco, can be transplanted into the tobacco chloroplast genome provides us with a powerful tool to study ways of manipulating this enzyme in higher plants. We have shown that replacing plant Rubisco with the simple large-subunit dimer version from the bacterium Rhodospirillum rubrum produces fully autotrophic and reproductive plants whose CO₂ response of photosynthesis is consistent with the content and kinetic properties of the transplanted Rubisco. We have continued using the R. rubrum Rubisco gene (rbcM) to extend our knowledge of gene regulation and protein expression in plastids in ways practically useful to the objective of controlling the expression of Rubisco transgenes in the chloroplasts of higher plants. Analyses will be presented of homoplasmic transformants that have been generated to allow us to examine how operon structure and codon bias influence the stability, abundance and translation of foreign Rubisco mRNA in higher plants plastids, and the physiological consequences for the plant as a whole. Where necessary the aadA-selectable marker gene, that confers resistance to spectinomycin, has been removed from transformed lines making the plastome of these plants amenable to additional genetic manipulation using spectinomycin selection. An outline of how these marker-free transformants were created and their future use in Rubisco manipulation studies will be presented.

KEY WORDS: Rubisco, Transgenic plants, Chloroplast transformation, Biotechnology