“…The enzymes catalyzing the steps in the C 4 pathway are also present in C 3 plants, and several, including PEPC (Hermans and Westhoff, 1990;Kawamura et al, 1992;Gowik et al, 2006), NADP-malic enzyme (Rajeevan et al, 1991;Marshall et al, 1996;Drincovich et al, 1998;Lai et al, 2002;Tausta et al, 2002), and pyruvate orthophosphate dikinase (Rosche et al, 1994;Imaizumi et al, 1997), have been examined in the context of C 4 evolution. 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).…”