Abstract
Rumex obtusifolius L. (Polygonaceae) is one of the most formidable weeds in infesting fields, arable lands and pastures through the world. In the early 20 century, the occurrence of R. obtusifolius in Japan was first reported in the northern island, whereas today it can be found in almost all areas.
Rumex plants contain high concentrations of oxalate. Excess uptake of this substance is toxic to animals. In plants, oxalate plays an important role as a source of hydrogen peroxide, which may act as defense molecules. Furthermore, some plants secrete oxalate to the rhizosphere, which could detoxify metallic ions.
In this investigation, we analyzed the oxalate metabolism in R. obtusifolius. Metabolite analysis by CE-MS showed that higher level of oxalate and amino acids were accumulated in R. obtusifolius. The analysis of R. obtusifolius grown in the dark indicated that citrate in stems play an important role in oxalate accumulation in leaves.
