Transcription of T-DNA in octopine and nopaline crown gall tumours is inhibited by low concentrations of alpha-amanitin.

Highly purified and physiologically active nuclei were isolated from four different octopine and nopaline crown gall lines. These nuclei exhibited a high endogenous RNA synthesizing activity involving all three RNA-polymerases I, II and III. Isolated nuclei were shown by Southern blotting to synthesize T-DNA specific RNA. This synthesis was shown to be sensitive to actinomycin D and therefore to be DNA-dependent. The transcription of the T-DNA was also inhibited for more than 90% by low concentrations of alpha-amanitin (0.7 micrograms/ml) indicating that the T-DNA, although from bacterial origin, is transcribed by the host RNA polymerase II.