Characterisation of the mycelial glycoproteins of the 'Ascochyta pea complex' (Ascochyta pisi Lib., Mycosphaerella pinodes (Berk. and Blox.) and Phoma medicaginis var. pinodella (Jones) Boerema)

Mycelial glycoproteins of the three phytopathogenic fungi causing Ascochyta blight on pea (Ascochyta pisi, Mycosphaerella pinodes (anamorph Ascochyta pinodes) and Phoma medicaginis var. pinodella) were investigated using affinity chromatography. Three types of functional structures were present in the three pathogens, N-glycosylated mannose structures, alpha-D-glucosyl residues and terminal alpha-D-galactosamine residues. The antigenic properties of the different glycoprotein fractions extracted from the three species were tested by ACP-ELISA using an antiserum produced against Mycosphaerella pinodes soluble mycelial extract. For all three fungi, the fraction containing a high mannose structure was preferentially recognised, whereas the fraction with glycosyl residues showed a weak reaction. The fraction containing alpha-D-galactosamine residues was not recognised. The most antigenic (mannose-rich) glycoprotein fraction of Mycosphaerella pinodes was used as immunogen to produce a polyclonal antiserum, in order to evaluate its specificity. The response (by ACP-ELISA) to this serum is similar for the three fungi. ((C) Inra/Elsevier, Paris.).