Atriplex spongiosa

Storey, R., Pitman, M.G., Stelzer, R. Carter, C. (1983). X-ray microanalysis of cells and cell compartments of Atriplex spongiosa. I. Leaves. Journal of Experimental Botany, 34, 778-94. 

Two other types of C4 pathways are recognized. In type-2 plants, Atriplex spongiosa) and type-3 Panicum maximum) plants, malate is replaced by aspartate as the major C4 acid transported to the bundle sheath cells. After transport, aspartate is converted to OAA by transamination. In type-2 plants, OAA is reduced to malate, which in turn is decarboxylated by NAD-malic enzyme in the bundle sheath cell mitochondria to give NADH, CO2 and pyruvate. In type-3 plants, OAA is decarboxylated in the cytosol by PEP carboxykinase in the presence of ATP, yielding PEP, CO2 and ADP. The return of carbon to the mesophyll cells for regeneration of the CO2 acceptor occurs as pyruvate (or alanine to maintain nitrogen balance) in type-2 and as PEP (or again perhaps as alanine) in type-3. These variations in the C4 pathway are summarized in Table I (see also Ref. 14). 

PEP carboxylase purified from Atriplex spongiosa. Reaction run at saturating PEP concentration and Km for Mg. Chelators at 1 mM. 

Table 4.5. Effect of NaCl on PEP carboxylases of Atriplex hastata and Atriplex spongiosa. V ax values were estimated from double reciprocal plots and expressed relative to 0 mM NaCl. The interaction coefficients n were determined from log-log graphs of the Hill equation ...

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