Comparative Genomics, Development, Physiology and Systematics of the Brassicaceae and Cleomaceae
Hibberd, Julian M .
Using Cleome to understand C4 photosynthesis.
C4 photosynthesis demands alterations to leaf development, cell biology and biochemistry. Together, these modifications concentrate CO2 around RuBisCO and increase the efficiency of photosynthesis. Different lineages of C4 plants use varying mechanisms to generate the C4 pathway. Although the biochemistry of C4 photosynthesis was described around 20 years ago, phylogenetic distance between Arabidopsis and the traditional C4 models has not facilitated the transfer of knowledge from Arabidopsis research to understanding C4 systems. We show that Cleome, a genus closely related to Arabidopsis, contains species spanning a developmental progression from C3 to C4 photosynthesis. The majority of species we assessed are C3 plants but have increased venation in leaves. Some C3 species have both increased venation and enlarged BS cells, and there is also a tendency to accumulate proteins and transcripts needed for C4 photosynthesis. Cleome gynandra shows all the characteristics needed for efficient C4 photosynthesis including alterations to leaf biochemistry, cell biology and development, and belongs to the NAD-ME sub-type. We have cloned a number of genes important for the C4 pathway from C. gynandra, and are placing these in Arabidopsis to determine the extent to which they are recognised by trans-factors in the C3 species. We are also developing tissue culture procedures to allow transformation of C. gynandra. Combined with the phylogenetic proximity of C. gynandra to Arabidopsis, the developmental progression from C3 to C4 photosynthesis within the genus identifies a potentially excellent new model to increase our understanding of C4 photosynthesis, and provide insights into its evolution.
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1 - University of Cambridge, Department of Plant Sciences, Downing Street, Downing Street, Cambridge, Cambs, CB2 3EA, United Kingdom
Presentation Type: Symposium or Colloquium Presentation
Location: Stevens 2/Hilton
Date: Monday, July 9th, 2007
Time: 4:30 PM