Analyzing the effect of decreasing cytosolic triosephosphate isomerase on Solanum tuberosum hairy root cells using a kinetic–metabolic model

A kinetic-metabolic model of Solanum tuberosum hairy roots is presented in the interest of understanding the effect on the plant cell metabolism of a 90% decrease in cytosolic triosephosphate isomerase (cTPI, EC 5.3.1.1) expression by antisense RNA. The model considers major metabolic pathways including glycolysis, pentose phosphate pathway, and TCA cycle, as well as anabolic reactions leading to lipids, nucleic acids, amino acids, and structural hexoses synthesis. Measurements were taken from shake flask cultures for six extracellular nutrients (sucrose, fructose, glucose, ammonia, nitrate, and inorganic phosphate) and 15 intracellular compounds including sugar phosphates (G6P, F6P, R5P, E4P) and organic acids (PYR, aKG, SUCC, FUM, MAL) and the six nutrients. From model simulations and experimental data it can be noted that plant cell metabolism redistributes metabolic fluxes to compensate for the cTPI decrease, leading to modifications in metabolites levels. Antisense roots showed increased exchanges between the pentose phosphate pathway and the glycolysis, an increased oxygen uptake and growth rate.