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Plant Physiology 73:347-352 (1983) © 1983 American Society of Plant Biologists Phytohormones, Rhizobium Mutants, and Nodulation in Legumes 1III. Auxin Metabolism in Effective and Ineffective Pea Root NodulesResearch School of Biological Sciences, Australian National University, Canberra, A.C.T. 2601, Australia
High specific activity [3H]indole-3-acetic acid (IAA) was applied to the apical bud of intact pea (Pisum sativum L. cv Greenfeast) plants. Radioactivity was detected in all tissues after 24 hours. More radioactivity accumulated in the nodules than in the parent root on a fresh weight basis and more in effective (nitrogen-fixing) nodules than in ineffective nodules (which do not fix nitrogen). For most samples, thin layer chromatography revealed major peaks of radioactivity at the RF values of IAA and indole-3-acetylaspartic acid (IAAsp) and further evidence of the identity of these compounds was obtained by chromatography in other systems. Disintegrations per minute due to IAA per unit fresh weight were significantly greater for root than for nodule tissue, but were not significantly different for effective and ineffective nodules. Radioactivity due to IAAsp, expressed both on a percentage basis and per unit fresh weight, was significantly greater for nodule than for root tissue and significantly greater for the effective nodules than for the ineffective nodules. When [3H]IAA was applied to effective nodules, IAAsp was the dominant metabolite in the nodule. The data suggest that metabolism of auxins may be important for the persistence of a functional root nodule.
2 Supported by a Postdoctoral Fellowship from the Australian National University and by Public Health Service Grant GM28027 from the National Institutes of Health. 1 Part II of this series is J. Badenoch-Jones, R. E. Summons, B. Entsch, B. G. Rolfe, C. W. Parker, and D. S. Letham 1982 Biomed Mass Spectrom 9: 429-437. Part I is Reference 1. This article has been cited by other articles:
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