Light indoleacetic acid

Indoleacetic acid is degraded in plants by a specific indoleacetic acid oxidase. This is a light-activatable flavoprotein enzyme coupled through hydrogen peroxide to a peroxidase (285 but cf. 463a, 805b). It apparently uses phenols as cofactors (296) but can be inhibited by polyphenols (305). The product of the reaction is still unidentified (836). 

A number of factors have been studied for their influence on nicotine production. Of these the negative effect of auxins, and in particular 2,4-D, on alkaloid production is worth mentioning (202-204,211,220, 225,226,229,255). In root cultures the addition of indoleacetic acid (lAA) also reduces alkaloid production (196). Light was reported to inhibit nicotine formation (50,255). In a green cell suspension, however, increased nicotine levels were found on illumination (229). Ikemeyer and Barz (243) reported that a photoautotrophic cell line of N. tabacum did not produce nicotine, whereas a heterotrophic cell line did accumulate this alkaloid. Elicitation with a preparation of the fungus Phytophthora megasperma did not affect the nicotine levels of these cell lines. Addition of organic acids to the medium resulted in increased alkaloid formation in callus cultures (up to 3.25%) (230). For a review of the various cultural factors which influence secondary metabolism, the reader is referred to Mantell and Smith (255). 

Serotonin S-hydroxytryptamine, M, 176.2, a plant and animal hormone. It is produced by hydroxylation of L-tryptophan to 5-hydroxytryptophan, followed by decarboxylation. The synthesis occurs in the central nervous system, lung, spleen and argentaffine light cells of the intestinal mucosa. S. is stored in thrombocytes and mast cells of the blood. It acts as a Neuro-transmitter (see), stimulates peristalsis of the intestine, and causes a dose-dependent constriction of smooth muscle. It stimulates the release from arterial endothelium of a dilator substance which counteracts its primary constricting effect [T.M. Cocks X A. Angus Nature 305 (1983) 627-630]. S. is a precursor of the hormone Melatonin (see). It is inactivated and degraded by monoamine oxidases and aldehyde oxidases to 5-hydroxy-indoleacetic acid. 

It is similarly well established that the removal of indoleacetic acid from metabolic availability may also follow more than one pathway. These include both oxidation by light and by enzymes, and con j ugation to other compounds. 

Fletcher RA, Zalik S (1964) Effect of light quality on growth and free indoleacetic acid content in Phaseolus vulgaris. Plant Physiol 39 328-333 Fonnesbech M (1972) Growth hormones and propagation of Cymbidium in vitro. Physiol Plant 27 310-316... 

Hemberg T, Larsson U (1972) Interaction of kinetin and indoleacetic acid in the Avena straight-growth test. Physiol Plant 26 104-107 Henson IE, Wareing PF (1974) Cytokinins in Xanthium strumarium A rapid response to short-day treatment. Physiol Plant 32 185-187 Hewett EW, Wareing PF (1973) Cytokinins in Populus x robusta (Schneid) Light effects on endogenous levels. Planta 114 119-129... 

Kohler K-H, Dorfler M, Goring H (1980) The influence of light on the cytokinin content of Amaranthus seedlings. Biol Plant 22 128-134 Kondo K, Watanable A, Imaseki H (1975) Relationships in actions of indoleacetic acid, benzyladenine and abscisic acid in ethylene production. Plant Cell Physiol 16 1001-1007... 

Morris DA, Briant RE, Thomson PG (1969) The transport and metabolism of relabelled indoleacetic acid in intact pea seedlings. Planta 89 178-197 Muir RM, Chang KD (1974) Effect of red light on coleoptile growth. Plant Physiol 54 286-288... 

I. In excised tissues and intact dwarf and normal plants. Plant Physiol 55 620-625 Davies PJ (1973) The uptake and fractional distribution of differentially labeled indoleacetic acid in light grown stems. Physiol Plant 28 95-100 Davies PJ (1974) The uptake and elution of indoleacetic acid by pea stem sections in relation to auxin induced growth. In Plant growth substances 1973. Hirokawa, Tokyo, pp 767-779... 

Koevenig JL (1973) Nonpolar movement of N6-benzyladenine- C in coleoptile, stem, petiole and floral organ sections. Can J Bot 51. 2079-2083 Koevenig JL, Jacobs WP (1972) Effect of light on basipetal movement of indoleacetic acid in green stem sections of Coleus. Plant Physiol 49 866-867 Koevenig JL, Sillix D (1973) Movement of lAA in sections from spider flower (Cleome hassleriana) stamen filaments. Am J Bot 60 231-235... 

Naqvi SM (1963) Transport studies with C -indoleacetic acid and C " -2,4-dichlorophen-oxyacetic acid in Coleus stems. Ph D Thesis, Princeton Univ, Princeton Naqvi SM (1974) The effect of sugar supplement on the kinetics of indoleacetic acid-2-transport in Zea mays L. coleoptile. Z Pflanzenphysiol 71 1-5 Naqvi SM (1975) Kinetics of auxin transport in light- and in dark-grown Zea mays L. coleoptile segments. Z Pflanzenphysiol 76 379-383 Naqvi SM (1976) Auxin in Zea mays L. coleoptile segments saturation of absorption and transport at various concentrations. Pak J Bot 8 47-52 Naqvi SM, Gordon SA (1964) Auxin transport in corn coleoptile sections. I. The effect of carbohydrate supplement on transport polarity, velocity, and capacity. Argonne Nat Lab Report 6971 190-193... 

Thimann KV, Wardlaw IF (1963) The effect of light on the uptake and transport of indoleacetic acid in the green stem of the pea. Physiol Plant 16 368-377 Thomson KSt, Leopold AC (1974) In vitro binding of morphactins and 1-N-naphthyl-phthalamic acid in corn coleoptiles and their effects on auxin transport. Planta 115 259-270... 

Thomson KSt, Hertel R, Muller S, Tavares JE (1973) 1-N-naphthylphthalamic acid and 2,3,5-triiodobenzoic acid In vitro binding to particulate cell fractions and action on auxin transport in corn coleoptiles. Planta 109 337-352 Thornton RM, Thimann KV (1967) Transient effects of light on auxin transport in the Avena coleoptile. Plant Physiol 42 247-257 Tsurumi S, Ohwaki Y (1978) Transport of " C-labeled indoleacetic acid in Vicia root segments. Plant Cell Physiol 19 1195-1206... 

Indoleacetic acid (lAA), a plant growth hormone, was known to be oxidized in vivo by a light-activated oxidase (Galston and Baker, 1949). It was subsequently postulated that this comprised a light-sensitive flavoprotein and a peroxidase, the two enzymes acting sequentially (Galston et al., 1953). The peroxidase requirement accounted for the sensitivity of the oxidation to catalase and cyanide. 

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