Free Auxins and Free Tryptophane in the Strawberry.

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Abstract
The quantitative evaluation (standard Avena test) of free auxins in ether extracts (2-4 hrs. at 0[degree]C in the dark) of strawberry achenes (var. Marshall) collected 3-30 days after pollination showed the existence of a sharp peak in the auxin concentration (on a dry weight basis) at 12 days after pollination. From the 9th to the 12th day after pollination, the auxin level increased 5 fold, reaching a maximum equivalent to 5 [mu]g of indoleacetic acid per gm dry weight. The concentration of free tryptophane (extracted with hot water after the precipitation of proteins with boiling ethanol) was found to be 2-3 times higher in the receptacles than in the achenes throughout the growth period, with a peak reaching 168 [mu]g of L-tryptophane per gm dry weight at the 12th day after pollination. Chromatographic separation of the substances present in the ether extracts indicated the absence of any strong auxin or inhibitor in the receptacles. On the contrary, the paper chromatograms of the achene extracts (12 days after pollination) showed the presence of at least 7 different growth-promoting substances. The extracts were purified from interfering fatty material and colored products bv shaking with hexane and acetonitrile. The acetonitrile fraction, which was found to contain most of the auxins, was chromatographed using either isopropanol-28% ammonia-water (8:1:1, v/v) or pure water. When the solvent front had reached 20 cm, the chromatograms were dried and cut into 1 cm sections, each of which was incubated at 25 [degree]C in the dark with 0.5 ml of a citrate-phosphate M/100 buffer (pH 5.0) containing 3% sucrose and with ten 4 mm sections of oat coleoptiles, var. Brighton. The elongation of the coleoptile sections after 20 hours was measured. Growth peaks appeared at Rfs 0.1, 0.23, 0.35, 0.5, 0.7, 0.83, and 0.95 in the isopropanol solvent and at Rfs 0.15, 0.30, 0.45, 0.70 and 0.95 in the water solvent. The most prominent of the auxins was identified as indoleacetic acid by its Rf, biological activity and color reactions with the (modified) Salkowski and Ehrlich reagents.