量研学術機関リポジトリ「QST-Repository」は、国立研究開発法人 量子科学技術研究開発機構に所属する職員等が生み出した学術成果（学会誌発表論文、学会発表、研究開発報告書、特許等）を集積しインターネット上で広く公開するサービスです。 Welcome to QST-Repository where we accumulates and discloses the academic research results(Journal Publications, Conference presentation, Research and Development Report, Patent, etc.) of the members of National Institutes for Quantum Science and Technology.
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Rumex plants (Polygonaceae) are widespread in the world. Some Rumex species such as sorrel (R. acetosa) are edible as baby leaf salad greens. R. obtusifolius L. (broad-leaved dock) is a perennial weed, which grows well in agricultural lands. It contains higher vitamin C (ascorbate) and amino acids and shows stress tolerance than many other Rumex species, whereas soluble oxalate is accumulated in leaves. Excess intake of Rumex leaves leads to mineral insufficiency, hypocalcaemia or kidney stones for human and livestock. Thus, the reduction of oxalate content in leaves is an important agricultural issue. In plant oxalate synthesis, three pathways (the isocitrate, glycolate, and ascorbate pathway) have been reported. However, it remains unknown which pathway or metabolite contributes the oxalate accumulation. In the present study, to clarify the mechanisms of oxalate synthesis, we focused on the metabolic alteration by ion beam-irradiation and performed metabolome analysis of the leaves of R. obtusifolius, which is one of the most oxalate rich-plant in Rumex plants, obtained from the seeds irradiated with ion beams. The results showed that oxalate contents in R. obtusifolius leaves were increased by seed irradiation of carbon ion beams. Correlation analysis of oxalate and other primary metabolite data set obtained by CE-MS (Capillary Electrophoresis-Mass Spectrometry) revealed that contents of oxalate precursors (citrate, isocitrate and ascorbate) had positive correlations with oxalate accumulation, whereas negative correlations were observed between oxalate and amino acids such as serine, glutamine, asparagine, arginine, and branched-chain amino acids. Principal component and hierarchical analyses suggested that the irradiation of ion beams affected carbon flow to the isocitrate pathway. These observations indicated that modulation of carbon flow to the isocitrate pathway is important to regulate oxalate levels in crops such as spinach and rice straw.
Impact of ion beam-irradiation on metabolisms in oxalate rich plant
