Abstract
(Benzamidooxy)acetic acid (common name benzadox) which has herbicidal properties was evaluated as a potential inhibitor of photosynthesis in C4 plants. Among enzymes of the C4 pathway, it was a relatively strong inhibitor of alanine aminotransferase in in vitro experiments at concentrations of 5mM. In benzadox treated leaves of Panicum miliaceum, a NAD-malic enzyme type C4 species, there was strong inhibition of both alanine and aspartate aminotransferase and of photosynthetic O2 evolution within one hour. Consistent with the inhibition of these enzymes of the C4 cycle, the pool sizes of metabolites of the cycle was altered: the aspartate level was increased two fold, while the levels of other metabolites such as pyruvate, alanine, oxalacetate and malate were decreased. Kinetic studies with partially purified alanine aminotransferase showed that benzadox is a competitive inhibitor with respect to alanine and a noncompetitive inhibitor with respect to 2-oxoglutarate. Comparisons between the structures and inhibitory actions of benzadox and (aminooxy)acetic acid, the latter a potent inhibitor of alanine and aspartate aminotransferases, suggest that in vivo, benzadox may exert its effect through metabolism to (aminooxy)acetic acid.
Similar content being viewed by others
Abbreviations
- benzadox:
-
(benzamidooxy)acetic acid
- DTE:
-
dithioerythritol
References
Edwards GE and Huber SC (1979) C4 metabolism in isolated cells and protoplasts. In M Gibbs and E Latzko, eds, Encyclopedia of Plant Physiology, New Series, Vol. 6, Springer-Verlag, Berlin, pp. 102–112
Edwards GE and Huber SC (1981) The C4 pathway. In MD Hatch and NK Boardman, eds, The Biochemistry of Plants, Photosynthesis, Vol. 8. Academic Press, New York, pp. 237–281
Edwards GE, Kanai R and Black CC (1971) Phosphoenolpyruvate carboxykinase in leaves of certain plants which fix CO2 by the C4-dicarboxylic acid pathway of photosynthesis. Biochem Biophys Res Commun 45:278–285
Hatch MD (1973) Separation and properties of leaf aspartate aminotransferase and alanine aminotransferase isoenzymes operative in the C4 pathway of photosynthesis. Arch Biochem Biophys 156:207–214
Hatch MD (1979) Mechanism of C4 photosynthesis in Chloris gayana: Pool sizes and kinetics of 14CO2 incorporation into 4-carbon and 3-carbon intermediates. Arch Biochem Biophys 194:117–127
Hatch MD and Kagawa T (1974) NAD malic enzyme in leaves with C4-pathway photosynthesis and its role in C4 acid decarboxylation. Arch Biochem Biophys 160: 346–349
Hatch MD and Mau S (1973) Activity, location, and role of aspartate aminotransferase and alanine aminotransferase isoenzymes in leaves with C4 pathway photosynthesis. Arch Biochem Biophys 156:195–201
Helmerhorst E and Stokes GB (1980) Microcentrifuge desalting: A rapid, quantitative method for desalting small amounts of protein. Anal Biochem 104:130–135
Hopper S and Segal HL (1962) Kinetic studies of rat liver glutamic-alanine transaminase. J Biol Chem 237:3189–3195
John RA and Charteris A (1978) The reaction of amino-oxyacetate with pyridoxal phosphate-dependent enzymes. Biochem J 171:771–779
Kanai R and Edwards GE (1973) Separation of mesophyll protoplasts and bundle sheath cells from maize leaves for photosynthetic studies. Plant Physiol 51:1133–1137
Ku SB and Edwards GE (1975) Photosynthesis in mesophyll protoplasts and bundle sheath cells of various types of C4 plants. IV. Enzymes of respiratory metabolism and energy utilizing enzymes of photosynthetic pathways. Z Pflanzenphysiol 77: 16–32
Lorimer GH, Badger MR and Andrews TJ (1977) D-ribulose-1,5-bisphosphate carboxylase-oxygenase. Improved method for the activation and assay of catalytical activities. Anal Biochem 78:66–75
Lowry OH, Rosebrough NJ, Farr AL and Randall RJ (1951) Protein measurement with the Folin phenol reagent. J Biol Chem 193:265–275
Schmitt MR and Edwards GE (1981) Photosynthetic capacity and nitrogen use efficiency of maize, wheat and rice: A comparison between C3 and C4 photosynthesis. J Exp Bot 32:459–466
Sugiyama T (1973) Purification, molecular, and catalytic properties of pyruvate phosphate dikinase from the maize leaf. Biochemistry 12:2862–2868
Uedan K and Sugiyama T (1976) Purification and characterization of phosphoenol-pyruvate carboxylase from maize leaves. Plant Physiol 7:906–910
Wintermans JFGM and De Mots A (1965) Spectrophotometric characteristics of chlorophylls and their pheophytins in ethanol. Biochim Biophys Acta 109:448–453
Author information
Authors and Affiliations
Additional information
This research was supported in part by gift funds from Monsanto Agricultural Products Company. St. Louis, Missouri, and by NSF Grant PCM-8107953.
Rights and permissions
About this article
Cite this article
Nakamoto, H., Ku, M.S.B. & Edwards, G.E. Inhibition of C4 photosynthesis by (benzamidooxy)acetic acid. Photosynth Res 3, 293–305 (1982). https://doi.org/10.1007/BF00034110
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00034110