Systemic accumulation of novel proteins in the apoplast of the leaves of potato plants following root invasion by the cyst-nematode Globodera rostochiensis

Systemic changes in gene expression have been analysed in potato plants following root infection with the cyst nematode Globodera rostochiensis. Root invasion by the pathogen induced major changes to occur in the composition of proteins extracted in intercellular fluid from the leaf apoplastic space. The changes involved the disappearance of innate leaf proteins and the accumulation of novel gene products. Analysis by SDS-PAGE indicated that the leaf polypeptides induced on nematode invasion are not cultivar or nematode pathotype-specific. Aspirin treatment of leaves induced a similar pattern to that induced systemically by nematodes, but several gene products were specific for the latter method of induction. In particular, two abundant [¹²⁵I]-Con A binding polypeptides of high M_r accumulated in intercellular fluid only on aspirin treatment. The results are discussed in the context of the role of the extracellular leaf proteins and their modulation by systemic signals.