Effects of dikegulac, a new growth regulator, on RNA syntheses in Spirodela

The effects of dikegulac sodium on plastid RNA syntheses werestudied, as dikegulac induces the formation of yellow misshapenleaves. It depressed uridine incorporation into both plastidand cytoplasmic ribosomal RNAs of axenically cultured Spirodela(duckweed). With short labeling time (1 hr) dikegulac specificallysuppressed the synthesis of a plastid 1.2 ? 10⁶ MW RNA species,as well as nonspecifically depressing incorporation. With longerlabeling time (24 hr), the incorporation into mature plastidrRNAs was suppressed to a greater extent than that into cytoplasmicrRNAs. The inhibitions of uridine incorporation caused by dikegulacare probably indirect and a reflection of its effect on othergrowth parameters. (Received September 25, 1976; )