Inhibition of Botrytis cinerea spore germination by immunoglobulins

Abstract

Lesion formation by spores of Botrytis cinerea on Vicia faba occurred within 15 h after inoculation. However, simultaneous application of various antisera delayed lesion formation until up to 65 h after inoculation. As the dilution of antiserum was increased, the length of the inhibitory period decreased and the fraction of the leaf surface that eventually became covered in lesions increased. Antisera of different antigen-binding specificity or different class of heavy chain (IgA, IgG, IgM) inhibited lesion formation, though IgM was the most effective. Antisera purified of other serum proteins were effective, but serum proteins such as albumins were not effective in causing inhibition of lesion formation. F(ab′)2 fragments of IgG molecules were as effective as the complete IgG molecule while Fc and light chain fragments were ineffective. Germination of B. cinerea spores on glass slides was inhibited by the same range of immunoglobulin molecules and fragments. We conclude that some constant portion of the antigen binding region of immunoglobulins inhibits lesion formation by inhibiting spore germination.