Two monoclonal antibodies (MAbs) were produced against soluble antigen
s from the 'Ascochyta complex' fungi. Specificity of MAbs was tested b
y ELISA using antigen-coated wells. MAbs secreted by the monoclonal hy
bridoma cell line JIM 44 recognized epitopes present in the antigen pr
eparations from Mycosphaerella pinodes and Phoma medicaginis var. pino
della, but not those present in preparations from Ascochyta pisi. At h
igh tissue culture supernatant concentration, MAbs produced by the mon
oclonal line JIM 45 recognized epitopes from all three fungi, however,
on dilution of MAb the antigens from A. pisi recognized preferentiall
y to those from M. pinodes and P. medicaginis var. pinodella. On the b
asis of hear and periodate treatment of the antigens from the three fu
ngi it can be concluded that the epitope recognized by JIM 44 is carbo
hydrate in nature, whereas that recognized by JIM 45 is proteinaceous
in nature, carried on a glycoprotein antigen. Antigen preparations fro
m other fungi, including other pea pathogens, non-pathogens associated
with pea and other fungi closely related to the 'Ascochyta complex',
were not detected with either of the two MAbs. Antigen preparations fr
om peas could be used to differentiate healthy and infected seeds in a
dot-blot assay, therefore indicating the potential of using the MAbs
in the development of a diagnostic test for infection of Pisum seeds b
y the 'Ascochyta complex' fungi.