Riboflavin Nullification of Inhibitory Actions of 3-Amino-1,2,4-Triazole on Seedling Growth

Hilton, James L.

doi:10.1104/pp.37.2.238

Cited by 15 publications

(5 citation statements)

References 17 publications

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“…Heretofore, the molecule has been consid ered relatively stable under most conditions but readily susceptible to microbial degradation. Amitrole is known to decompose in the presence of riboflavin and light (6,11,12,17) with the ultimate evolution of C0 2 5 originat ing from the amitrole molecule. The amitrole nucleus also is readily disrupted by high energy processes involv ing free radical systems (5,17).…”

Section: Resultsmentioning

confidence: 99%

Chemical Versus Microbial Decomposition of Amitrole in Soil

Kaufman¹,

Plimmer²,

Kearney

et al. 1968

Weed sci.

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Degradation of 3-amino-l,2,4-triazole-5-C14 (amitrole-5-C14) in autoclaved, potassium azide, ethylene oxide, and dry-heat sterilized soil was compared with that observed in nonsterile soils by measuring evolved C14O2. Amitrole degradation occurred in azide and ethylene oxide-sterilized and nonsterile soils but not in autoclaved soils. Only slight degradation occurred in autoclaved soil re-inoculated with mixed cultures of soil microorganisms isolated from soil in which amitrole had been rapidly degraded. Addition of EDTA-Na to nonsterile and ethylene oxide sterilized soils reduced amitrole degradation. Addition of organic amendments to amitrole treated soil stimulated microbial activity but reduced amitrole degradation. Addition of specific metallic salts to certain soils increased the rate of amitrole degradation. Amitrole degradation occurred rapidly in several free radical generating chemical systems. These results and additional observations indicate that amitrole degradation, at least in three soils examined, was largely a chemical process, and that microbial involvement was only indirect.

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Section: Resultsmentioning

confidence: 99%

Chemical Versus Microbial Decomposition of Amitrole in Soil

Kaufman¹,

Plimmer²,

Kearney

et al. 1968

Weed sci.

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“…If it turns out that there is only one cyclase enzyme, the observation that flavins are able to nullify the inhibitory' action of amitrole on the growth and chlorosis of barky seedlings (Hilton 1962) offers an opportunity for further investigation. Lycopeoe cyclase of Synechococcus, Envinia species, as well as phytoene desaturase from Synechococcus contain in the N-terminal amino acid sequences a flavin binding motif {Cunninghan et al i994).…”

Section: Discussionmentioning

confidence: 99%

Expression of chloroplastic and cytosolic glutamine synthetase in barley leaves after cold-sensitive blocking of beta-carotene synthesis by amitrole or mutation

Zito¹,

Gough²,

Marcato³

et al. 1995

Physiol Plant

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G. 1995. Expression of chloroplastic and cytosolic glutamine synthetase in barley leaves after cold-sensitive blocking of |3-carotene synthesis by amitrole or mutation. -Physiol. Plant. 94: 535-544.3-Amino-l,2,4-triazole (amitrole) provided to germinating barley at 20°C in tbe light led to bleached seedling leaves and photodynamic destruction of chloroplast structure, whereas normal greening and chloroplast ultrastructure was obtained when the seedlings developed in the presence of amitrole in the light al 30°C. Mass spectrometric analysis of the extractable herbicide demonstrated the same content of amitrole in leaves developed at 20 and 30°C. A very similar temperature-sensitive syndrome is characteristic for tbe nucJear gene mutant ligrina-o^ in barley. Amitrole and the mutation were shown to inhibit the cycliration of lycopene, leading to severe deficiencies in j3-carotene and its xanthophyll derivative lutein. Besides accumulation of lycopene. also its precursors phytoene, phytofluene and f-carotene accumulated. Inhibition of carotenoid biosynthesis by amitrole and the mutation at 20°C in the light led to a strong reduction of bcth transcript and protein levels for chloroplastic glutamine synthetase (GS;) while transcript amount and protein of the cytosolic isoenzyme (GS|) were unaffected. At 30°C increased levels of mRNA for the chloroplastic isoform GS, were observed in wild type, mutant and amitrole-treated seedlings, but protein levels remained unchanged. Turnover rates of the GS2 protein were the same at 20 and 30°C. This extensive translational control of chloroplastic GSj synthesis was also observed in a heat shock experiment, which revealed transiently increased mRNA levels for chloroplastic GS2 but unchanged protein levels.Permissive synthesis of /3-carotene and chloroplastic glutamine synthetase (GS,) at 30°C in the presence of amitrole or the tigrina-o''' mutation might be due to two alternative pathways of ionone ring formation using either lycopene or neurosporene as substrates for cyclization.

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“…T h e y postulated an alkylation of the pro tein by amitrole based on free radical formation when riboflavin and light were present. Hilton (7) found that riboflavin deactivated amitrole i n both light and dark, suggesting the possibility that light may not be necessary to produce amitrole-free radical. Possibly, endogenous energy systems initiate a free radical of amitrole that i n turn alkylates bean protein i n the dark.…”

Section: Discussionmentioning

confidence: 99%

Influence of Amitrole Upon Protein Metabolism in Bean Plants

Brown

Carter

1968

Weed sci.

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No effect was shown of 3-amino-l,2,4-triazole (amitrole) upon the incorporation of alanine or histidine into soluble protein in bean (Phaseolus vulgaris L.) hypocotyls grown in darkness. The metabolic derivative of amitrole, β-(3-amino-1,2,4-triazolyl-l-)α-ala-nine (hereinafter referred to as 3-ATAL), also had no effect upon histidine incorporation. Serine incorporation was increased 56% in the presence of amitrole, but this may result from a reduction of endogenous serine pools. No evidence indicates a general disruption of protein synthesis. Activity from amitrole-5-14C was readily incorporated into bean protein, but hydrolysis revealed no 3-ATAL. Most of the activity was recovered as amitrole. Amitrole in the presence of riboflavin and light attacked bovine serum albumin, probably by free radical formation. Hydrolysis of bovine serum albumin revealed mainly amitrole. Apparently, the entry of amitrole into bean protein is by free radical formation.

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Riboflavin Nullification of Inhibitory Actions of 3-Amino-1,2,4-Triazole on Seedling Growth

Abstract: The phy.siological meclhanismls involved inl the toxic actions of 3-amino-1 ,2,4-triazole (aamitrole)

Cited by 15 publications

References 17 publications

Chemical Versus Microbial Decomposition of Amitrole in Soil

Chemical Versus Microbial Decomposition of Amitrole in Soil

Expression of chloroplastic and cytosolic glutamine synthetase in barley leaves after cold-sensitive blocking of beta-carotene synthesis by amitrole or mutation

Influence of Amitrole Upon Protein Metabolism in Bean Plants

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