Nitrate acts as a signal to induce organic acid metabolism and repress starch metabolism in tobacco
Scheible WR, Gonzales-Fontes A, Lauerer M, Muller-Rober B, Caboche M, Stitt M: Nitrate acts as a signal to induce organic acid metabolism and repress starch metabolism in tobacco. Plant Cell 1997, 9:1-17. These authors have investigated the effects of nitrate on carbon and nitrogen metabolism in wild-type tobacco plants and low nitrate reductase expressing transformants. These experiments allowed the distinction between events triggered by nitrate itself and changes produced more indirectly as a result of nitrate assimilation. Nitrate initiates an extensive program of gene expression, resulting in co-ordinate alterations in the activities of enzymes in several metabolic pathways.
Accumulation of nitrate in the shoot acts as a signal to regulate shoot-root allocation in tobacco
Scheible WR, Lauerer M, Schulze ED, Caboche M, Stitt M: Accumulation of nitrate in the shoot acts as a signal to regulate shoot-root allocation in tobacco. Plant J 1997, 11:671 - 691. Tobacco genotypes with low expression of nitrate reductase resemble a nitrate-deficient wild-type with respect to their growth rates and content of organic nitrogenous compounds, but accumulate high levels of nitrate. Nitrate accumulation in the shoots is accompanied by inhibition of root growth and an increase in the shoot:root ratio.
