| Autor: |
He JZ; Institut de Recherche en Biologie Végétale, Université de Montréal, 4101 Rue Sherbrooke Est, Montréal, QC H1X 2B2, Canada., Dorion S; Institut de Recherche en Biologie Végétale, Université de Montréal, 4101 Rue Sherbrooke Est, Montréal, QC H1X 2B2, Canada., Carmona-Rojas LM; Institut de Recherche en Biologie Végétale, Université de Montréal, 4101 Rue Sherbrooke Est, Montréal, QC H1X 2B2, Canada.; Grupo de Biotecnologiía, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia, Medelliín 050010, Colombia., Rivoal J; Institut de Recherche en Biologie Végétale, Université de Montréal, 4101 Rue Sherbrooke Est, Montréal, QC H1X 2B2, Canada. |
| Abstrakt: |
Nutritional phosphate deficiency is a major limitation to plant growth. Here, we monitored fluxes in pathways supporting respiratory metabolism in potato ( Solanum tuberosum ) cell cultures growing in control or limiting phosphate conditions. Sugar uptake was quantified using [U- 14 C]sucrose as precursor. Carbohydrate degradation through glycolysis and respiratory pathways was estimated using the catabolism of [U- 14 C]sucrose to 14 CO 2 . Anaplerotic carbon flux was assessed by labeling with NaH 14 CO 3 . The data showed that these metabolic fluxes displayed distinct patterns over culture time. However, phosphate depletion had relatively little impact on the various fluxes. Sucrose uptake was higher during the first six days of culture, followed by a decline, which was steeper in Pi-sufficient cells. Anaplerotic pathway flux was more important at day three and decreased thereafter. In contrast, the flux between sucrose and CO 2 was at a maximum in the mid-log phase of the culture, with a peak at Day 6. Metabolization of [U- 14 C]sucrose into neutral, basic and acidic fractions was also unaffected by phosphate nutrition. Hence, the well-documented changes in central metabolism enzymes activities in response to Pi deficiency do not drastically modify metabolic fluxes, but rather result in the maintenance of the carbon fluxes that support respiration. |
