This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Web of Science (17) Citing Articles via Google Scholar Google Scholar Articles by Wielgat, B. Articles by Kahl, G. Search for Related Content PubMed PubMed Citation Articles by Wielgat, B. Articles by Kahl, G. Agricola Articles by Wielgat, B. Articles by Kahl, G.

Articles

Gibberellic Acid Activates Chromatin-bound DNA-dependent RNA Polymerase in Wounded Potato Tuber Tissue ¹

Günter Kahl^b

^a Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland, Department of Biology, University of Frankfurt am Main, Germany

Chromatin-bound DNA-dependent RNA polymerases react upon wounding of white potato tuber tissues with an increase in activity, which is additionally enhanced to 300% in the presence of 0.1 micromolar gibberellic acid (GA₃). 2,4-Dichlorophenoxyacetic acid is only weakly effective and indoleacetic acid not at all. Wounding and treatment with GA₃ affect template availability of chromatin only slightly. The hormone has no effect on chromatin-bound RNA polymerases, if added in vitro.

The enzymes from intact, wounded, and hormone-treated tissues possess similar characteristics: their activity is dependent on the presence of all four ribonucleotides and a divalent cation such as Mg²⁺ or Mn²⁺. However, the sensitivity of the enzymes from different preparations toward -amanitin differs. Total RNA polymerase activity of chromatin was inhibited by -amanitin to about 44% in intact, to about 22% in wounded, and only 15% in GA₃-treated tissues. The relative activities of polymerases I and II were estimated by varying the (NH₄)₂SO₄ and -amanitin concentrations in the assay system. It is evident that GA₃ preferentially stimulates polymerase I and hence ribosomal RNA synthesis. RNA polymerase II is but slightly affected by GA₃. Nearest neighbor frequency analysis revealed that the RNA synthesized by the enzymes from the intact tuber is different from that of wounded or GA₃-treated tissues.