Aspartate-dependent alanine production by leaf discs of Amaranthus paniculatus, an aspartate utilizing NAD-malic enzyme type C₄ plant

Abstract

Illuminated leaf discs of Amaranthus paniculatus formed alanine rapidly after infiltration with aspartate. a-oxoglutarate and glutamate accelerated aspartate-dependent alanine production. Alanine was also formed by A. paniculatus leaf discs infiltrated with oxalacetate; this production was stimulated only by glutamate. Our results confirm that alanine can be formed rapidly from aspartate in C₄ plants. Aspartate-dependent alanine production was stimulated greatly by light. The stimulatory effect of light could almost be replaced by ATP in presence of sodium ions. These findings are discussed in relation to a possible light-dependent active transport of amino acids into the bundle sheath, mediated by Na⁺-dependent ATPase activity.