Analysis of genes expressed in second stage juveniles of the potato cyst nematodes Globodera rostochiensis and G-pallida using the expressed sequence tag approach

Expressed sequence tag (EST) projects offer a rapid route to the discovery of novel genes. Genes expressed in a wide range of parasitic nematodes of medical or veterinary importance have been investigated using EST analysis but these techniques have not yet been applied to plant parasitic nematodes. We describe a small scale EST project using cDNA libraries made from the two species of potato cyst nematode, Globodera rostochiensis and G. pallida, and assess the utility of this approach to identify mRNAs encoding abundantly expressed secreted proteins and other proteins present in the nematode at the onset of parasitism. Approximately 1000 sequences were obtained from G. rostochiensis and 100 from G. pallida. A variety of genes was characterised and approximately 11% of the cDNAs sequenced were apparently PCN specific. Secreted proteins identified included a novel PCN homologue of chorismate mutase, a cDNA recently cloned from the gland cells of Meloidogyne javanica. The results obtained justify a much larger scale application of this technology to these parasites.