Polyamines and flowering. Spermidine biosynthesis in the different whorls of developing flowers of nicotiana tabacum L

Sonia Scaramagli, Marina Franceschetti, Anthony J. Michael, Patrizia Torrigiani, Nello Bagni

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16 Scopus citations

Abstract

The regulation of S-adenosylmethionine decarboxylase (SAMDC; EC 4.1.1.1), a key enzyme of polyamine biosynthesis, was analysed at the level of transcript accumulation, enzyme activity, and free and conjugated polyamine accumulation during floral development in tobacco (Nicotiana tabacum L., cv. Samsun). SAMDC was investigated at five different stages of flower development and in each floral whorl. Using a PCR-derived homologous SAMDC probe, a transcript of approximately 2.0 kb was detected. In floral whorls, transcript accumulation was lower in anthers than in ovaries. In the latter, SAMDC activity did not parallel transcript accumulation. Although the SAMDC transcript was relatively abundant in pollen, no enzyme activity could be detected. Hybridisation with a spermidine synthase (SPDsyn; EC 2.5.1.16) cDNA probe from the closely related species Datura stramonium indicated that the pattern of accumulation of the 1.4 lib tobacco spermidine synthase mRNA was similar, to that of SAMDC. The levels of free polyamines and their conjugates were measured in flowers, and spermidine was the predominant polyamine in both the free and conjugated forms; the class of perchloric acid- soluble conjugates was the most represented (90% of the total spermidine pool). In pollen, tne level of free spermidine was half that of the insoluble spermidine conjugates, whereas soluble conjugates were undetectable. The pattern of SAMDC activity paralleled spermidine conjugate accumulation and consequently the size of the spermidine pool, in fertile floral whorls.

Original languageEnglish (US)
Pages (from-to)229-237
Number of pages9
JournalPlant Biosystems
Volume133
Issue number3
DOIs
Publication statusPublished - Nov 1 1999

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Keywords

  • Flower development
  • Gene expression
  • Nicotiana tabacum
  • S- adenosylmethionine decarboxylase
  • Spermidine
  • Spermidine synthase

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Plant Science

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