Studies on Tobacco Alkaloids. I. Changes in Nicotine and Nornicotine Content in Nicotiana.

Tso, T. C.; Jeffrey, R. N.

doi:10.1104/pp.31.6.433

Cited by 25 publications

(14 citation statements)

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“…Results presented here, which were obtained by employing N'5, tend to confirm and extend those reported in Part I of this paper (11). These results indicate that the synthesis of nicotine alkaloids follows a stepwise course involving a number of reactions and possibly alternate pathways.…”

Section: Resultssupporting

confidence: 80%

“…The present experiments confirm previous observations that nicotine can be converted to nornicotine in the leaf. However, since nornicotine was detected in the root at an early stage of seedling growth, as described in the previous paper (11), and was found in the work reported here to contain a higher percentage excess N15 than the nicotine in plants shifted into N15-containing nutrient culture during their later growth, it appears that nornicotine can be formed independently either in root or in leaf of tobacco plants.…”

Section: Resultsmentioning

confidence: 67%

“…The preceding paper (11) reports the changes in nicotine and nornicotine content as related to growth conditions of two selections of Nicotiana plants which contain principally nornicotine. Certain results obtained proved difficult to explain on the basis of current theories which state that nicotine synthesis is conducted predominantly in the root (4) and subsequient conversion to nornicotine takes place only in the leaf (5).…”

mentioning

confidence: 99%

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Studies on Tobacco Alkaloids. II. The Formation of Nicotine and Nornicotine in Tobacco Supplied with N¹⁵.

Tso¹,

Jeffrey²

1957

Plant Physiol.

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Section: Resultssupporting

confidence: 80%

Section: Resultsmentioning

confidence: 67%

mentioning

confidence: 99%

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Studies on Tobacco Alkaloids. II. The Formation of Nicotine and Nornicotine in Tobacco Supplied with N¹⁵.

Tso¹,

Jeffrey²

1957

Plant Physiol.

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“…No difference was observed between enzymic oxidation of putrescine and N-methylputrescine by leaf and root extracts of Burley 21 (a high nicotine, low nornicotine genotype) and a high nornicotine cultivar, "Robinson Medium Broadleaf." Putrescine was utilized as a substrate to a greater extent than N-methylputrescine by leaf extracts compared with root extracts of both cultivars.…”

mentioning

confidence: 99%

“…Nornicotine is synthesized primarily by demethylation of nicotine in the leaf. This conclusion is based on nornicotine levels rising "at the expense of" nicotine levels in both green and cured leaf (3,4,21,23), and isotopic labeling studies (10,19). Other studies have indicated that nornicotine may be synthesized independently of nicotine (8,9,22).…”

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confidence: 99%

Nicotine Biosynthetic Enzyme Activities in Nicotiana tabacum L. Genotypes with Different Alkaloid Levels

Saunders¹,

Bush²

1979

Plant Physiol.

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Young plants of five Nicotiana tabacum L. genotypes were examined for activity of nicotine biosynthetic enzymes. Genotypes near isogenic except at two loci each with two alleles controlling nicotine level were used in a comparison of the four homozygous allelic combinations producing high, high intermediate, low intermediate, and low nicotine levels in a 'Burley 21" background. Putrescine N-methyltransferase (EC 2.1.1.53) and quinolinic acid phosphoribosyltransferase (EC 2.4.2.19) activities in root tissue of these four genotypes were proportional to leaf nicotine level, whereas N-methylputrescine oxidase activity in root tissue differed in proportion and ranking. Quinolinic acid phosphoribosyltransferase activities in leaf tissue were lower than in roots, but no differences were found among the four genotypes. The homozygous recessive alleles at either locus affect levels of all three enzyme activities examined in roots. Each locus seems to be involved in regulation of nicotine metabolism, but whether directly as a regulatory locus or indirectly through the metabolic product of a structural locus is not known.No difference was observed between enzymic oxidation of putrescine and N-methylputrescine by leaf and root extracts of Burley 21 (a high nicotine, low nornicotine genotype) and a high nornicotine cultivar, "Robinson Medium Broadleaf." Putrescine was utilized as a substrate to a greater extent than N-methylputrescine by leaf extracts compared with root extracts of both cultivars. It was concluded that genetic differences in levels of nicotine and nornicotine were not due to differences in enzymic oxidation of these two precursors during alkaloid biosynthesis.Nicotine is the predominant alkaloid in commercial tobacco cultivars, where it is found in concentrations of 2 to 5% of dry weight. Nicotine level as influenced by cultural practices of nitrogen fertilization, plant decapitation, water regime, and axillary bud control has been reviewed recently (2). Low total alkaloid levels are associated with homozygous recessive alleles at both the A and B genetic loci, and intermediate alkaloid levels are found when the homozygous recessive alleles are present at only one of the two loci (I 1).Nicotine, composed of single pyridine and N-methylpyrrolidine rings linked together, is synthesized primarily in the root (1,5). Support for the role of ornithine decarboxylase putrescine Nmethyltransferase (EC 2.1

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Nachweis der Nornicotin‐Bildung in isolierten Tabakwurzeln

Schröter¹,

Engelbrecht²

1957

Archiv der Pharmazie

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Studies on Tobacco Alkaloids. I. Changes in Nicotine and Nornicotine Content in Nicotiana.

Cited by 25 publications

References 11 publications

Studies on Tobacco Alkaloids. II. The Formation of Nicotine and Nornicotine in Tobacco Supplied with N¹⁵.

Studies on Tobacco Alkaloids. II. The Formation of Nicotine and Nornicotine in Tobacco Supplied with N¹⁵.

Nicotine Biosynthetic Enzyme Activities in Nicotiana tabacum L. Genotypes with Different Alkaloid Levels

Nachweis der Nornicotin‐Bildung in isolierten Tabakwurzeln

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Studies on Tobacco Alkaloids. I. Changes in Nicotine and Nornicotine Content in Nicotiana.

Cited by 25 publications

References 11 publications

Studies on Tobacco Alkaloids. II. The Formation of Nicotine and Nornicotine in Tobacco Supplied with N15.

Studies on Tobacco Alkaloids. II. The Formation of Nicotine and Nornicotine in Tobacco Supplied with N15.

Nicotine Biosynthetic Enzyme Activities in Nicotiana tabacum L. Genotypes with Different Alkaloid Levels

Nachweis der Nornicotin‐Bildung in isolierten Tabakwurzeln

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Studies on Tobacco Alkaloids. II. The Formation of Nicotine and Nornicotine in Tobacco Supplied with N¹⁵.

Studies on Tobacco Alkaloids. II. The Formation of Nicotine and Nornicotine in Tobacco Supplied with N¹⁵.