The tomato nia gene complements a Nicotiana plumbaginifolia nitrate reductase-deficient mutant and is properly regulated.
A nitrate reductase (NR) deficient mutant of Nicotiana plumbaginifolia totally impaired in the production of functional nia transcript and protein was restored for NR activity by transformation with a cloned tomato nia gene. The transgenic plants expressed from undetectable to 17% of the control NR activity in their leaves. Restoration of growth rates comparable to the wild type was obtained for transgenic plants expressing as little as 10% of the wild-type activity showing that nitrate reduction is not a growth-limiting factor in the wild-type plant. The analysis of the transgene expression showed that the tomato nia gene transcription was regulated by light, nitrate and a circadian rhythm as in tomato plants. These results suggest that all the cis-acting sequences involved in these regulations are contained in the 3 kb upstream region of the tomato nia gene and are still functional in transgenic N. plumbaginifolia plants. The amount of NR transcript synthesized from the tomato nia gene was reduced when a functional N. plumbaginifolia nia locus was introduced by sexual crosses. These data support the hypothesis that nitrate reduction is regulated by nitrate-derived metabolites as demonstrated in fungi.
Dorbe
M F
MF
Laboratoire de Biologie Cellulaire, INRA, Versailles, France.
Caboche
M
M
Daniel-Vedele
F
F
D000641:Ammonia / Q000494:pharmacology; D015152:Blotting, Northern; D015139:Blotting, Southern; D002940:Circadian Rhythm / Q000502:physiology; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects / Q000502:physiology*; D005816:Genetic Complementation Test; D008027:Light; D009154:Mutation / Q000235:genetics; D050901:Nitrate Reductase; D009565:Nitrate Reductases / Q000235:genetics*; D009566:Nitrates / Q000494:pharmacology; D030821:Plants, Genetically Modified / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D010947:Plants, Toxic; D014026:Nicotiana / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D014170:Transformation, Genetic / Q000235:genetics
D009566:Nitrates; D000641:Ammonia; D009565:Nitrate Reductases; D050901:Nitrate Reductase