Article

Molecular and General Genetics MGG

, Volume 236, Issue 2, pp 203-208

First online:

Cloning and expression of distinct nitrite reductases in tobacco leaves and roots

  • Jocelyne KronenbergerAffiliated withLaboratoire de Biologie Cellulaire, INRA
  • , Andrée LepingleAffiliated withLaboratoire de Biologie Cellulaire, INRA
  • , Michel CabocheAffiliated withLaboratoire de Biologie Cellulaire, INRA
  • , Hervé VaucheretAffiliated withLaboratoire de Biologie Cellulaire, INRA

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Summary

Three tobacco nitrite reductase (NiR) cDNA clones were isolated using spinach NiR cDNA as a probe. Sequence analysis and Southern blot hybridization revealed four genes in tobacco. Two of these genes presumably derived from the ancestral species Nicotiana tomentosiformis, the other two from the ancestor N. sylvestris. Northern blot analysis showed that one gene from each ancestral genome was expressed predominantly in leaves, whilst RNA from the other was detected mostly in roots. The accumulation of both leaf and root NiR mRNAs was induced by nitrate and repressed by nitrate- or ammonium-derived metabolites. In addition, the expression of the root NiR gene was detectable in leaves of a tobacco nitrate reductase (NR)-deficient mutant. Thus, the regulation of expression of tobacco NiR genes is comparable to the regulation of expression of barley NR genes.

Key words

Tobacco Nitrate reductase Nitrite reductase Regulation Mutants