AUXIN-INDUCED GROWTH OP TUBER TISSUE OP JERUSALEM ARTICHOKE: III. EFFECT OF ACTINOMYCIN D ON AUXIN-INDUCED EXPANSION GROWTH AND RNA SYNTHESIS1

Abstract

The following results were obtained using tissue slices excised from cold-stored Jerusalem artichoke tubers. Actinomycin D at the concentration of 20 μg/ml given during the aging period did not affect the subsequent expansion growth caused by auxin or auxin plus kinetin. Actinomycin D given in the growth period, on the other hand, strongly inhibited the expansion growth of tissue slices aged in the absence of the antibiotic. In the growth period, auxin or auxin plus kinetin promoted the incorporation of uracil-2-¹⁴C into RNA fraction. Actinomycin D inhibited the incorporation of ³²P orthophosphate into ribosomal RNA during the aging period. In the growth period, the incorporation of ³²P into RNA was enhanced by auxin and was inhibited by actinomycin D, more remarkably in ribosomal RNA than in lighter RNA.