1. In the present paper the hypothesis that P730 acts through the activation of “potentially active genes” has been tested. The phytochrome-induced anthocyanin synthesis of the mustard seedling, Sinapis alba L., has been used as a photoresponse (Bertsch and Mohr 1965). It has been shown that phytochrome-induced anthocyanin synthesis can be blocked by the application of actinomycin D, which is known to be a highly specific inhibitor of DNA-dependent RNA synthesis.

Wir verwenden die phytochromabhängige Anthocyansynthese des Senfkeimlings, eine typische „Photomorphose” dieser Art.—Durch Actinomycin D, einen spezifischen Inhibitor der Transcription, und Puromycin, einen spezifischen Inhibitor der Translation, kann die phytochrominduzierte Anthocyansynthese in genau der Weise beeinflußt werden, wie man es auf Grund der Hypothese zu erwarten hat.