Phylogeny of Flaveria (Asteraceae) and inference of C₄ photosynthesis evolution

Abstract

A well-resolved phylogeny of Flaveria is used to infer evolutionary relationships among species, biogeographical distributions, and C(4) photosynthetic evolution. Data on morphology, life history, and DNA sequences (chloroplastic trnL-F, nuclear ITS and ETS) for 21 of 23 known species were collected. Each data set was analyzed separately and in combination using maximum parsimony and Bayesian analyses. The phylogeny of Flaveria is based on the combined analysis of all data. Our phylogenetic evidence indicates that C(3) Flaveria are all basal to intermediate (C(3)-C(4) and C(4)-like) and fully expressed C(4) Flaveria species. Two strongly supported clades (A and B) are present. Using this phylogeny, we evaluate the current systematics of the genus and suggest the removal and reevaluation of certain taxa. We also infer the center of origin and dispersal of Flaveria species. Multiple origins of photosynthetic pathway intermediacy in Flaveria are recognized. C(3)-C(4) intermediacy has evolved twice in the genus and is found to be evolutionarily intermediate in clade A, but not necessarily in clade B. C(4)-like photosynthesis is also derived once in each clade. In addition, fully expressed C(4) photosynthesis may have evolved up to three times within clade A.

Evolution and Function of acis-Regulatory Module for Mesophyll-Specific Gene Expression in the C4 DicotFlaveria trinervia

“…A phylogenetic tree based on the sequences of these eight promoters is in agreement with the phylogeny of the genus Flaveria as proposed by McKown et al (2005) (Figure 6A). The ppcA promoter tree indicates that the ppcA genes of clade A and clade B evolved separately from the ancestral ppcA genes, which resemble the ppcA genes of the present basal C 3 Flaveria species.…”

“…According to the recently published phylogeny of the genus Flaveria, which was based on both morphological and molecular characteristics, all C 4 and C 4 -like species form a distinct clade (clade A), while the C 3 species F. pringlei and F. cronquistii are basal (McKown et al, 2005). The C 3 -C 4 intermediate species of the genus are contained within clade B (McKown et al, 2005).…”

“…The C 3 -C 4 intermediate species of the genus are contained within clade B (McKown et al, 2005). We were interested in whether a MEM1 sequence is also found in the ppcA genes of C 3 -C 4 intermediate Flaveria species and which states of MEM1 submodules are present.…”

“…This genus contains closely related C 3 , C 4 , and numerous C 3 -C 4 intermediate species (Ku et al, 1991;McKown et al, 2005). These C 3 -C 4 species differ quantitatively in the expression of C 4 photosynthetic traits and are considered, at least partly, evolutionary intermediates (Monson and Moore, 1989).…”

Loss of the Transit Peptide and an Increase in Gene Expression of an Ancestral Chloroplastic Carbonic Anhydrase Were Instrumental in the Evolution of the Cytosolic C4 Carbonic Anhydrase in Flaveria

“…Many of these studies (Hermans and Westhoff, 1990;Rajeevan et al, 1991;Rosche et al, 1994;Marshall et al, 1996;Drincovich et al, 1998;Lai et al, 2002) used members of the genus Flaveria as model organisms for understanding the steps involved in the evolution of C 4 photosynthesis, because this group of closely related plants contains individual species demonstrating C 3 , C 4 , or intermediate C 3 -C 4 photosynthesis, indicating that the evolution toward C 4 photosynthesis is ongoing in this genus (McKown et al, 2005). The results from several of these studies demonstrated that the genes encoding the enzymes important in C 4 photosynthesis evolved through the duplication of ancestral C 3 genes followed by the neofunctionalization of one copy, which involved increased gene expression in specific organs and cell types (for review, see Monson, 2003).…”