Senescence metabolomics of <i>Nicotiana tabacum</i> L. VBI-0 heterotrophic suspension cultures

Abstract

BACKGROUND: Heterotrophic cell cultures are widely used as a model in plant biology. During a culture cycle the composition of the medium changes: the sucrose and other substrates are depleted, metabolism products are accumulated and the density increases. Finally, arrest of a growth is followed by cell death in a short time. These processes are accompanied with physiological alterations, corresponding to senescence. AIM: To resolve metabolic features of tobacco cells in growing and stationary senescent suspension cultures VBI-0. MATERIALS AND METHODS: Nicotiana tabacum VBI-0 cells were cultured in suspension MS medium supplied with 3% sucrose. Cells were sampled at 7th day, during intensive growth, and at 28th day, when the culture was in the stationary phase. The GC-MS method was used to profile the metabolites. RESULTS: Sucrose depletion in media caused starvation of heterotrophic tobacco cell culture and was associated with a decrease in the accumulation of free amino acids. At the same time, the level of pentoses and complex sugars, including sucrose, increased, while the levels of glucose and fructose were not changed significantly and levels of hexose phosphates decreased. During culture senescence cells showed higher levels of accumulation of malate, pyruvate and some other carboxylates. CONCLUSIONS: The metabolomic data indicate that culture senescence was associated with a drop in amino acids metabolism, a decrease in the activity of the upper part of glycolysis, and the accumulation of complex sugars, pentoses and carboxylates.