SARA FUCHS - Department of Chemical Immunology, Weizmann Institute of Science, Rehovot, Israel

Antibodies with specificity towards abscisie acid (ABA) were produced in rabbits. These antibodies were used for assaying ABA by the inhibition of inactivation of modified bacteriophage. For this assay conjugates of ABA with bacteriophage T 4 were prepared and characterized. Such chemically modified bacteriophages were completely inactivated by the specific anti-ABA serum and this inactivation was inhibited by free ABA. The identification and quantitative determination of ABA in plant extracts by this method are demonstrated and the method is compared with a common bioassay.