Emergent Growth: An Auxin-Mediated Response

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RESUMO

Restoration of oxygenated conditions following 15 minutes to 2 hours of anoxia causes light-grown pea (Pisum sativum L. var. Alaska) stem segments to elongate 100 to 200% more than continuously aerated segments. This “emergent growth” response takes place in the presence of 5 mm F−, an inhibitor of anaerobic respiration; therefore, a build-up of glycolytic products does not appear to be the mechanism underlying emergent growth. “Acid growth” does not appear to account directly for the hyperelongation, as extracellular pH does not drop following a return to aerobic conditions. Studies with 14C-indoleacetic acid indicate that auxin is freed from some previously unavailable pool during O2-limited treatments. We suggest, therefore, that emergent growth is a response to auxin which is released during anaerobiosis: the newly mobile or diffusible auxin promoting growth when O2 is no longer limiting.

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