Next, Brown et al. have a fairly comprehensive report on the origin of C4 photosynthesis, a topic I've been interested in since my undergrad days. Check out the abstract:
C4 photosynthesis allows increased photosynthetic efficiency because carbon dioxide (CO2) is concentrated around the key enzyme RuBisCO. Leaves of C4 plants exhibit modified biochemistry, cell biology, and leaf development, but despite this complexity, C4 photosynthesis has evolved independently in at least 45 lineages of plants. We found that two independent lineages of C4 plant, whose last common ancestor predates the divergence of monocotyledons and dicotyledons about 180 million years ago, show conserved mechanisms controlling the expression of genes important for release of CO2 around RuBisCO in bundle sheath (BS) cells. Orthologous genes from monocotyledonous and dicotyledonous C3 species also contained conserved regulatory elements that conferred BS specificity when placed into C4 species. We conclude that these conserved functional genetic elements likely facilitated the repeated evolution of C4 photosynthesis.
Here's my take on the origin of C4 photosynthesis:
A baraminological analysis of subtribe Flaveriinae (Asteraceae: Helenieae) and the origin of biological complexity
Woods et al. 2011. Second-Order Selection for Evolvability in a Large Escherichia coli Population. Science 331:1433-1436.
Brown et al. 2011. Independent and Parallel Recruitment of Preexisting Mechanisms Underlying C4 Photosynthesis. Science 331:1436-1439.
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