| Sumario: | C4photosynthetic plants have evolved from C3ancestors and are characterized by differential expression of several hundred genes. Strict compartmentalization of key C4enzymes either to mesophyll (M) or bundle sheath cells is considered a crucial step towards the evolution of C4photosynthesis. In this study, we demonstrate that the 5′‐flanking sequences of the C4type phosphoenolpyruvate carboxylase (Ppc) gene from three C4grass species could drive M‐cell‐specific expression of a reporter gene in rice. In addition to that, we identified about 450 bp (upstream of their transcription start site) of the analyzedC4Ppcpromoters contain all the essential regulatory elements for driving M‐cell‐specific expression in rice leaves. Importantly, four motifs of conserved nucleotide sequences (CNSs) were also determined, which are essential for the activity of the promoter. A putative interaction between theCNSs and an unknown upstream element(s) is required for driving M‐cell‐specific expression. This work identifies the evolutionary conservation ofC4Ppcregulatory mechanisms of multiple closely related C4grass species.
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