The genus Flaveria – our model to study the evolution of C4 photosynthesis

The genus Flaveria belongs to the Asteracean family, more widely known as composite plants. The English common name for Flaveria is yellowtop, referring to their small yellow flowers (see figure A). In nature they can be found, depending on the species, in North and South America, Australia, Asia and Africa.

Why is this genus now interesting for our studies, what makes it special?

C4 photosynthesis is a special and very efficient form of photosynthesis. C4 photosynthesis occurred in at least 66 lineages among the plant kingdom independently (Sage et al., 2012). One can therefore assume that the evolution from C3 to C4 photosynthesis was rather easy in biological terms. To study these changes the plant genus Flaveria functions as one of our favourite models. One of the major benefits of this genus is that it not only contains C3 and C4 species, but also a range of species that exhibit an intermediate type of photosynthesis. One example for a species of each type of photosynthesis can be seen in figure B. This allows us to analyze the changes a plant has to undergo in the transition from C3 to C4 photosynthesis.

Physiological analyses were conducted already many years ago and led to the characterization of the photosynthesis type of the different species. The phylogeny of the Flaveria species was molecularly analyzed in detail (McKown et al., 2005). Recently the transcriptomes of nine Flaveria species were published (Mallmann et al., 2014) thereby providing us with the information of all transcribed genes at a given time. In addition one of the C4 species, Flaveria bidentis, is transformable with the soil bacterium Agrobacterium tumefaciens, i.e. we can implant new genes in these plants and thus the molecular tools are becoming more numerous.