Molecular Ecology and Evolution
Christin, Pascal-Antoine , Edwards, Erika , Sage, Rowan .
Phylogenetics of Molluginaceae and evolution of C4 photosynthesis.
C4 photosynthesis is an adaptation that consists in multiple modifications over the ancestral C3 state. Several C3-C4 intermediates have been reported, which can help reconstructing the evolutionary paths from C3 to C4 photosynthesis. The first described C3-C4 plant belongs to Molluginaceae, a family that contains C3 and C4 plants as well as various C3-C4 intermediates, but accurate phylogenies for this family are lacking. Here, we reconstructed phylogenies for Molluginaceae and related clades using plastid and nuclear markers and determined the photosynthetic type of each accession. Plastid and nuclear phylogenies were congruent but showed strong discrepancies with classical taxonomy. The Mollugo genus was highly polyphyletic and several Mollugo species were not resolved as monophyletic, suggesting the existence of cryptic species. C4 accessions formed two closely related groups separated by a C3 species. Analyses of genes involved in the C4 pathway and morphological characters showed that these two groups evolved their C4 trait independently, from a common ancestor with some C4-like properties. The C3-C4 intermediates were nested in different clusters of C3 species, which suggests that Mollugo species departed from C3 photosynthesis several times independently, questioning the potential drivers of frequent photosynthetic transitions in this family.
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1 - Brown University, Ecology and Evolutionary Biology, 80 Waterman St, Box G-W, Providence, RI, 02912, USA
2 - Brown University, Department of Ecology and Evolutionary Biology, 80 Waterman St., Providence, RI, 02912, USA
3 - University of Toronto, Department of Botany, 25 Willcocks Street, Toronto, Ontario, M5S 3B2, Canada
Presentation Type: Oral Paper:Papers for Topics
Location: 552A/Convention Center
Date: Wednesday, August 4th, 2010
Time: 8:45 AM