ARS | Publication request: An antagonist treatment in combination with tracer experiments revealed isocitrate pathway dominant to oxalate biosynthesis in Rumex obtusifolius L

Submitted to: Metabolomics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 21, 2012
Publication Date: May 13, 2013
Citation: Miyagi, A., Uchimiya, M., Kawai-Yamada, M., Uchimiya, H. 2013. An antagonist treatment in combination with tracer experiments revealed isocitrate pathway dominant to oxalate biosynthesis in Rumex obtusifolius L. Metabolomics. 9(3):590-598.

Interpretive Summary: Certain class of plants accumulate oxalate in leaves as a defense mechanism and to detoxify aluminum. However, biosynthetic pathways have not been fully elucidated for oxalate accumulation in leaves of polygonaceous plants. This study employed rigorous metabolite analysis using capillary electrophoresis mass spectrometry techniques as well as statistical analysis to understand how itaconate (antagonist to isocitrate) plays a role in oxalate accumulation. The results suggested that excess oxalate in leaves originated from isocitrate pathway that utilized citrate formed in stems of the plant.

Technical Abstract: Oxalate accumulates in leaves of certain plants such as Rumex species (Polygonaceae). Oxalate plays important roles in defense to predator, detoxification of metallic ions, and in hydroxyl peroxide formation upon wounding/senescence. However, biosynthetic pathways of soluble oxalate are largely unknown. In the present study we analysed Rumex obtusifolius L. treated with itaconate (an antagonist to isocitrate). Comprehensive metabolome analysis using capillary electrophoresis-mass spectrometry showed that oxalate content of “new leaves” was notably down-regulated by itaconate, as opposed to the accumulation of citrate. The 13CO2 feeding experiment revealed that oxalate accumulation in new leaves was affected by citrate translocation from stems. The results suggested that excess oxalate in new leaves of R. obtusifolius was synthesized primarily via the isocitrate pathway utilizing citrate delivered from stems.