Figure 5.

Selected Enzyme Activities and Metabolite Contents along a Maize Leaf.

(A) Enzyme activities. Error bars indicate sd of four biological replicates.

(B) Expression pattern of the major isoform for each enzyme.

(C) Normalized abundance of four C₄ cycle metabolites, with absolute values in slice three: malate, 13.5 mmol/mg DW; Asp,4 mmol/mg DW; Ala, 4 mmol/mg DW.

(D) Model of the C₄ cycle in maize. Arrow widths equal approximate flows, bold arrows represent enzyme activities, open arrowheads indicate transport between the cells, and green stars denote plastid-localized steps. pyr, pyruvate; 3-PGA, 3-phosphoglycerate; MDH, malate dehydrogenase; GAP-DH, glycerinaldehyde-3-phosphate dehydrogenase.