Fate of 13C in metabolic pathways and effects of high CO2 on the alteration of metabolites in Rumex obtusifolius L.

Abstract

In present study, in vivo turn-over of 13CO2 to organic acids such as oxalate and citrate in Rumex obtusifolius L. was explored. Conversion of fixed carbon to oxalate was studies using "new leaves", i. e., leaves removed from 2-month-old-plants grown under different environmental conditions. Collected new leaves and stems were subjected to metabolomic analyses using capillary electrophoresis mass spectrometry. The results showed the mobilization of metabolites from stems to new leaves, where active TCA cycle and oxalate pathways occurred. The 13C labeling experiments also indicated that these pathways are active in new leaves. Subsequently, we compared the effects of high carbon dioxide level (1000 ppm) and nutrients (Hoagland's formulation) on the metabolite accumulation in R. obtusifolius. Data analysed by both principal component and hierarchical clustering analyses revealed significant changes in metabolite accumulation. The accumulation of most abundant metabolite oxalate in leaves was affected by both high CO2 as the carbon source and nutrients. We suggest that the common weed R. obtusifolius may proliferate in cultivated lands under high CO2 level, a potential cause of global warming. © 2011 Springer Science+Business Media, LLC.