Expression of a deregulated tobacco nitrate reductase gene in potato increases biomass production and decreases nitrate concentration in all organs.
We investigated the physiological consequences for nitrogen metabolism and growth of the deregulated expression of an N-terminal-deleted tobacco nitrate reductase in two lines of potato (Solanum tuberosum L. cv Safrane). The transgenic plants showed a higher biomass accumulation, especially in tubers, but a constant nitrogen content per plant. This implies that the transformed lines had a reduced nitrogen concentration per unit of dry weight. A severe reduction in nitrate concentrations was also observed in all organs, but was more apparent in tubers where nitrate was almost undetectable in the transgenic lines. In leaves and roots, but not tubers, this nitrate decrease was accompanied by a statistically significant increase in the level of malate, which acts as a counter-anion for nitrate reduction. Apart from glutamine in tubers, no major changes in amino acid concentration were seen in leaves, roots or tubers. We conclude that enhancement of nitrate reduction rate leads to higher biomass production, probably by allowing a better allocation of N-resources to photosynthesis and C-metabolism.
Djennane
Samia
S
Station d'Amélioration de la Pomme de Terre et des Plantes à Bulbes, INRA, Domaine de Kéraïber, 29260, Ploudaniel, France.
Quilleré
Isabelle
I
Leydecker
Marie-Thérèse
MT
Meyer
Christian
C
Chauvin
Jean-Eric
JE
D018533:Biomass; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D050901:Nitrate Reductase; D009565:Nitrate Reductases / Q000235:genetics*; D030821:Plants, Genetically Modified / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D011198:Solanum tuberosum / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development; D014026:Nicotiana / Q000201:enzymology*
D009565:Nitrate Reductases; D050901:Nitrate Reductase