Carbon dioxide fixation by auxin treated tissues

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Abstract
Indoleacetic acid (IAA) or naphthalene acetic acid in growth promoting concentrations stimulated C14O2 fixation from NaHCl4O3 by Avena coleop-tiles. The IAA-induced stimulation was maximal at a concentration of 10-5[image] and was detectable within a short period. After fixation for a few hours the bulk of the C14 fixed could be located in citric-isocitric acid and aspartic acid; in the presence of low concentrations of IAA, fixation into malic acid and asparagine was stimulated remarkably with an accompanying decrease in tagged aspartic acid. IAA also promoted C14 -fixation into polyuronide hemicelluloses, polysaccharides and [alpha]-cellulose with relatively long incubation periods; it had a distinct inhibitory effect on fixation into protopectin. Of the various co-factors tried DPNH alone gave results which had some resemblance to the effects of IAA. IAA in concentrations which inhibit root growth also stimulated C14-incorporation by Avena roots in a manner largely similar to that observed with coleoptile tissues.