ANTIBODIES AGAINST FUNGAL CONIDIA AND ANTIBIOTICS INHIBIT PHENYLALANINE AMMONIA-LYASE ACTIVATION IN CITRUS

Antibodies raised against Trichoderma harzianum conidia prevented accu mulation of Phenylalanine ammonia-lyase (PAL, E.C. 4.3.1.5.) in Citrus . The observed effect of the antibodies is produced by a delay in the formation of the fungal germination tube. An increase of PAL activity of ca. 7 fold in C. limon and C sinensis seedlings, and of ca. 2 fold in C. paradisii seedlings was found, as an hypersensitive response to inoculation with T. harzianum conidia. This increase in activity was d ue to <<de novo>> synthesis of the enzyme as demonstrated by the effec t of protein-synthesis inhibitors and by immunotitration.