[Studies on the effect of auxin and hydroxyproline on incorporation of proline into proteins of wheat coleoptile segments].

Wheat coleoptile segments were pulse labeled with C-14-proline (pro) for different 2-hour periods within a total incubation of 8 hours. The effect of auxin naphthalene-1-acetic acid (NAA) and hydroxyproline (hypro) on the pro incorporation into cell wall fraction and soluble proteins was measured. 1. NAA causes a reduced incorporation of C-14-pro into soluble proteins and into the cell wall fraction within the first 2-hour period. Pulse labeling at later periods results in a marked increase of C-14-pro incorporation into the cell wall fraction due to NAA without change in the incorporation rate into soluble proteins. 2. There is no influence of NAA or hypro on the hydroxylation of pro to hypro. 3. From the second to the sixth hour of incubation the increase of pro incorporation into the cell wall fraction effected by auxin is closely correlated with the stimulation of cell expansion growth. 4. Hypro in growth inhibiting concentration (10(-2)M) does not show a clear influence upon pro hydroxylation, but it does have a remarkable effect in reducing auxin stimulated pro incorporation into the cell wall fraction From the data given it can be assumed that auxin may exert a direct function in regulating cell wall protein synthesis.