Isolation of Proteins Related to the β-Lectin from Potato which Bind to Hyphal Wall Components of Phytophthora infestans

Proteins from potato cells which recognize fungal cell wall components of Phytophthora infestans were isolated after passage of a potato homogenate through an affinity column which contained bound fungal cell wall components. Bound potato proteins were eluted with NN′-diacetylchitobiose, and fractionated by SDS-polyaciylamide gel electrophoresis. Eluted proteins from cv. Yukijiro (R₁-gene) and cv. Irish Cobbler (r-gene) had similar profiles and the same apparent Mr, 66, 58 and 41.5 kD and other proteins with lower molecular weight. Only the 41.5 kD and lower molecular weight proteins reaeted with polyclonal antibodies against the β-lectin from the R₁ cultivar, Rishiri. The surfaces of protoplasts from cvs Yukijiro and Irish Cobbler also reacted with the antibodies to the lectin. Treatment of potato protoplasts with hyphal cell wall components of P. infestans caused cytoplasmic aggregation, a response characteristic of the hypersensitive reaction. Oligomers of N-acetyl glucosamine reduced the ability of fungal cell wall components to cause this cytoplasmic aggregation. These results suggest that binding between fungal cell wall eomponents and certain potato proteins is sensitive to N-acetylglucosamine, and may play a role in the hypersensitive reaction.