The effect of plant growth regulators on DNA

Abstract

Purified DNA from pea seedlings was incubated at low ionic strength with each of the following plant growth regulators: Indole-3-acetic acid (IAA); Gibberellic acid (GA); 2,4-Dichlorophenoxy acetic acid (2,4-D); 2,4,5-Trichlorophenoxy acetic acid (2,4,5-T); Indole-3-propionic acid (IPA); Indole-3-butyric acid (IBA); 6-Benzylaminopurine (BAP) and 6-Furfurylaminopurine (KIN). Alterations in the thermal denaturation transition profiles and the melting temperature (Tm) were used to evaluate the effect of these substances on the conformation of the treated DNA. At concentrations of 10 −4 M to 10 −3 M, IAA, GA, 2,4-D and 2,4,5-T caused a decrease of the Tm. BAP and KIN at a concentration of 10 −4 M prevented the hyperchromicity resulting from denaturation of DNA. At 10 −4 M, IBA and IPA caused an upward shift of the Tm, but at higher concentrations both compounds caused a downward shift of the Tm.