Plants have evolved different versions of photosynthesis to maintain efficiency under diverse environmental conditions. While the vast majority of plants use C3 photosynthesis, some plants evolved a turbo-charged form of photosynthesis called C4, which is used by our most productive food and bioenergy crops. The C4 system evolved from the ancestral C3 type via a series of modifications to leaf biochemistry and anatomy, which inevitably created intermediate states along these evolutionary trajectories. These C3-C4 intermediates use a rare physiology called C2 photosynthesis. Thus, C2 plants tend to occur in lineages that evolved C4 photosynthesis, and are key to understanding the evolutionary paths to C4 emergence.
One genus of sedges (Eleocharis) seems to include particularly diverse photosynthetic types. In addition to some C3 Eleocharis species, preliminary work suggests that C2 and C4 photosynthesis may have evolved multiple times independently in this genus. Moreover, some wetland Eleocharis species have facultative C4 photosynthesis, which means that they can turn this special mode of photosynthesis on and off under different environmental triggers. Facultative C4 photosynthesis is extremely rare, but may be important for these plants to tolerate the particularly variable environmental conditions expected under climate change.
This PhD studentship will investigate the evolution of both facultative and constitutive C2 and C4 photosynthesis in Eleocharis sedges by characterizing the photosynthetic diversity and evolutionary relationships in Eleocharis specimens and the capacity to induce C2 and C4 physiology across the phylogeny. The student will do this through a combination of glasshouse experiments with physiology, leaf anatomy, and stable carbon isotope measurements at Lancaster University, fieldwork in the United States in collaboration with Washington State University, and phylogenomic analyses undertaken during a 6-week placement at the laboratories of the Royal Botanic Gardens, Kew.
First-class or 2.1 (Hons) degree or Masters degree (or equivalent) in biology, ecology or plant sciences is required.