In hypocotyl segments of mung bean (Phaseolus mungo L.) seedlings, exogenously supplied indoleacetic acid was rapidly conjugated mainly into indoleacetylaspartic acid, which was inactive in inducing ethylene production. Kinetin is known to stimulate indoleacetic acid-induced ethylene production. The mechanism of kinetin action on indoleacetic acid-induced ethylene production by hypocotyl segmen...

Auxin-induced ethylene production by mung bean (Phaseolus mungo L.) hypocotyl segments was markedly inhibited by 2,4-dinitrophenol regardless of whether or not kinetin was present. Uptake of indoleacetic acid-2-(14)C was also inhibited in the presence of 2,4-dinitrophenol. Segments treated only with indoleacetic acid rapidly converted indoleacetic acid into indole-3-acetylaspartic acid with tim...

Indoleacetic acid at 0.017 millimolar inhibited the formation of three peroxidase isoenzymes in both soluble and wall-bound enzyme fractions of wheat coleoptile (Triticum vulgare) tissue. Hydroxyproline at 1 millimolar prevented the indoleacetic acid-induced inhibition. Indoleacetic acid oxidase activity in the soluble fraction was decreased by indoleacetic acid and was restored by hydroxyproli...

Pea (Pisum sativum var. Alaska) and bean (Phaseolus vulgaris var. Red Kidney) stem sections treated with indoleacetic acid-1-(14)C, indoleacetic acid-2-(14)C, and indoleacetic acid-5-(3)H were homogenized, extracted with phenol, and the water-soluble, ethanol-insoluble material subjected to further fractionation. Following an 18-hour incubation period in indoleacetic acid-1-(14)C, most of the l...

Indoleacetic acid oxidase in tobacco callus cultures (Nicotiana tabacum L., cv. White Gold) was composed of at least two groups of isoenzymes, which were distinctly different in electrophoretic mobilities and in responses to growth substances. Indoleacetic acid had dual effects; at low concentrations it promoted the development of two fast-migrating indoleacetic acid oxidase isoenzymes, but at ...

Cycloheximide inhibited ethylene production in excised pea root tips treated with high levels of indoleacetic acid (100 mum and 10 mum). In contrast, cycloheximide did not inhibit ethylene production induced by a lower concentration (1 mum) of indoleacetic acid unless it was added 2 hours before the indoleacetic acid treatment. These observations suggest that indoleacetic acid has two effects o...

The uptake and accumulation of exogenous indoleacetic acid-(14)C by intact rice coleoptiles were examined. The absorption of exogenous indoleacetic acid was controlled by phytochrome, while the subsequent accumulation of this indoleacetic acid in various portions of the coleoptile was complex, and the effect of red light in this system was small compared to the alteration of the uptake of indol...

Activity of indoleacetic acid oxidase was shown to increase following a period of water stress. Two fractions of indoleacetic acid oxidase were extracted from plant extracts. Similarly, two protein peaks (determined by ultraviolet absorption) were isolated. One peak, associated with an indoleacetic acid oxidase peak, increased following water stress. The second peak, not associated with extract...

Indoleethanol-(14)C was applied to intact cucumber seedlings and to hypocotyl segments. The presence of indoleacetic acid-(14)C in tissue extracts was demonstrated by thin layer radiochromatography. There was no evidence of conversion of indoleacetic acid to indoleethanol. It is suggested that the growth-promoting activity of indoleethanol is due to its conversion to indoleacetic acid.

The effects of gibberellic acid on the longevity and elongation of variously aged, debladed petioles of Coleus blumei were studied, with particular reference to the hypotheses 1) that auxin increases longevity by increasing growth, and 2) that gibberellic acid acts by increasing the endogenous levels of auxin.Gibberellic acid, substituted for the leaf blades, significantly decreased longevity o...