Effect of light on growth and metabolic activities in pea pisum sativum cultivar alaska seedlings 2. changes in the iaa content and activities of enzymes involved in the iaa biosynthesis during growth
Suzuki, Y.; Kamisaka, S.; Yanagisawa, H.; Miyata, S.; Masuda, Y.
Biochemie und Physiologie der Pflanzen (BPP) 176(1): 35-43
The effect of light and dark conditions on the IAA content and the activities of tryptophan aminotransferase, indolepyruvic acid decarboxylase, indoleacetaldehyde oxidase and amine oxidase in pea (P. sativum L., cv. Alaska) seedlings were studied. The endogenous IAA content was higher in shoots of dark-grown pea seedlings than in those of light-grown ones. When seedlings grown in the dark were transferred to light, the endogenous IAA content decreased. The light-grown seedlings were transferred to darkness, the IAA content increased. No significant difference in the effect of the light and dark conditions occurred on the activities of tryptophan aminotransferase, indolepyruvic acid decarboxylase and indoleacetaldehyde oxidase in the epicotyl. The activity in the apical part of amine oxidase, which catalyzes the conversion of tryptamine to indoleacetaldehyde, was inhibited considerably under light conditions. The increased IAA content in the dark conditions is not likely to depend on specific regulatory mechanisms at the enzyme level. Although the amine oxidase activity was high in the dark-grown pea seedlings, the function of this enzyme in IAA biosynthesis remains unsolved.