Figure 2.

Genes associated with C₄ photosynthesis are coordinated in the ancestral C₃ state. (a) The enzymes PPDK and PCK (red) both act during gluconeogenesis in germinating Arabidopsis seedlings [60]. Both genes have been co-opted into the C₄ pathway (b) where PPDK regenerates PEP from pyruvate in the M and PCK acts as a C₄ acid decarboxylase releasing CO₂ around RuBisCO in the BS cells. Abbreviations as for figure 1.