The composition of Erysiphe pisi haustorial complexes with special reference to the neckbands

Abstract

Haustorial complexes of Erysiphe pisi were isolated from the Pisum sativum, mutant line Argenteum, and their composition studied using fluorescent stains and enzymic digestions. Special attention was paid to the composition of the neckbands. Both A and B neckbands were stained with dyes specific for β-glucans, lipidic substances, protein and sulphydryl groups. The A band seemed to be richer in β-1,3-glucans than the B band, which more often contained β-1,4-glucans. The B band also contained proteinaceous compounds more often than the A band. Both neckbands were rich in lipidic substances. However, the organization of lipidic compounds and their attachment to other wall components differed in the A and B bands as indicated by digestion with lipase, esterase, zymolase, cellulase and Novozym 234, chitinase, ligninase, laccase and combinations of these enzymes. In the A band, lipidic components appeared to be more highly esterified than those in the B band, and bound to β-1,3-glucans and chitin. In the B band, attachment of the lipidic substances to a proteinaceous component was indicated, with masking of the lipids by wall polysaccharides. The junction between the extrahaustorial membrane and the haustorial neck at the neckbands was never seen to be completely degraded.