Abstract
Maize liquid endosperm extracts contain the enzymes necessary for all of the steps of the plant IAA biosynthetic pathway from tryptophan, and provide a means to assay the pathway in vitro. We have analyzed the reactions in the presence of a series of indole and indole-like analogues in order to evaluate the potential of these compounds to act as inhibitors of IAA biosynthesis. Such inhibitors will be useful to investigate the tryptophan to IAA pathway, to determine the precursors and intermediates involved, and to select for mutants in this process. A number of such compounds were tested using in vitro enzyme assays for both the tryptophan dependent IAA biosynthesis pathway and for tryptophan synthase β activity. Some compounds showed strong inhibition of IAA biosynthesis while having only a slight effect on the reaction rate of tryptophan synthase β. These results: (1) show that IAA biosynthesis can be selectively inhibited relative to tryptophan biosynthesis; (2) suggest potential ways to screen for IAA biosynthetic pathway mutations in plants; and (3) provide additional tools for studies of IAA biosynthesis in plants.
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References
Chauhan YS, Rathore VS, Garg GK and Bhargava (1978) Detection of an indole oxidizing system in maize leaves. Biochem Biophys Res Commun 83: 1237–1245
Epstein E, Cohen JD and Bandurski RS (1980) Concentration and metabolic turnover of indoles in germinating kernels of Zea mays L. Plant Physiol 65: 415–421
Ilic N, Normanly J and Cohen JD (1996) Quantification of free plus conjugated indole-3-acetic acid in Arabidopsis requires correction for the non-enzymatic conversion of indolic nitriles. Plant Physiol 111: 781–788
Jensen PJ and Bandurski RS (1994) Metabolism and synthesis of indole-3-acetic acid (IAA) in Zea mays. Levels of IAA during kernel development and the use of in vitro endosperm systems for studying IAA biosynthesis. Plant Physiol 106: 343–351
Michalczuk L, Ribnicky DM, Cooke TJ and Cohen JD (1992) Regulation of indole-3-acetic acid biosynthesis in carrot cell cultures. Plant Physiol 100: 1346–1353
Muir RM and Lantican BP (1968) Purification and properties of the enzyme system forming indoleacetic acid. In:Wightman F and Setterfield G (eds) Biochemistry and Physiology of Plant Growth Substances. Ottawa: Runge, pp 259–272
Normanly J, Cohen JD and Fink GR (1993) Arabidopsis thaliana auxotrophs reveal a tryptophan-independent biosynthetic pathway for indole-3-acetic acid. Proc Natl Acad Sci USA 90: 10355–10359
Rekoslavskaya NI (1995) Pathways of indoleacetic acid and tryptophan synthesis in developing maize endosperm: studies in vitro. Russian J Plant Physiol 42: 143–151
Rekoslavskaya NI and Bandurski RS (1994) Indole as a precursor of indole-3-acetic acid in Zea mays. Phytochemistry 35: 905–909
Widholm JM (1971) Control of tryptophan biosynthesis in plant tissue cultures: lack of repression of anthranilate and tryptophan synthetases by tryptophan. Physiol Plant 25: 75–79
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Ilić, N., Östin, A. & Cohen, J.D. Differential inhibition of indole-3-acetic acid and tryptophan biosynthesis by indole analogues. I. Tryptophan dependent IAA biosynthesis. Plant Growth Regulation 27, 57–62 (1999). https://doi.org/10.1023/A:1006103902155
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DOI: https://doi.org/10.1023/A:1006103902155