Immunological Studies of Plant Hormones.

Specific antibodies to two plant, hormones, namely indole-3-acetic acid and gibberellic acid, were produced in rabbits which were immunized with conjugates of either hormone to hemocyanin. The specific antibodies obtained were used for assaying the hormones by several immunological assays. The most sensitive assay reported in this paper, for the determination of indole-3-acetic acid and gibberellic acid, is the inhibition of inactivation of modified bacteriophage. For this assay conjugates of either hormone with bacteriophage T4 were prepared and characterized. Such chemically modified bacteriophages were completely inactivated by the respective specific antiserum and this inactivation was inhibited by the free hormone. The specificity of the antibodies produced was tested by a series of cross-reactions. There was no immunological cross-reaction between the two hormones which can, therefore, be determined independently. However, antibodies to indole-3-acetic acid cross-reacted with chemically related compounds such as indole-acetyl-ε-amino caproic acid, tryptamine and tryptophan. The immunological specificity of different gibberellins tested was found to be in good correlation with the biological specificity. [ABSTRACT FROM AUTHOR]