Metabolism of α-Ketoglutarate by Roots of Woody Plants

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Abstract
The uptake and metabolismof a-ketoglutarate-5-C14 by peach [Prunus persica], apple [Pyrus malus], and privet [Ligustrum vulgare] root tissues were studied over vartaus time intervals. As much as 80% of the absorbed C14 appeared as C14O2 in 320 min. in peach roots. Apple and privet roots were less effective in this conversion with the bulk of the Cl4 found in the organic acid fraction. This indicates differences in organic acid metabolism among species of woody plants. The C14 accumulated in malate earlier and in larger quantities than in citrate. Both glutamate and aspartate were labeled in 10 min. and glutamate was labeled as early as 3 min. The labeling pattern does not clearly distinguish between the synthesis of glutamate by glutamic dehydrogenase or bytransaminationwithoxaloacetate. The rapid metabolism of [alpha]-ketoglutarate to glutamate by the 3 species studied indicates the presence of enzyme systems important in amino acid synthesis in the roots of woody plants.[long dash]Authors.