Analysis of expressed sequence tags derived from pea leaves infected by Peronospora viciae f. sp. pisi.

A cDNA library was constructed from field pea leaves infected by the downy mildew pathogen, Peronospora viciae f. sp. pisi, using a suppression subtractive hybridisation approach. The library consists of 399 expressed sequence tags, from which 207 unisequences were obtained after sequence assembly. Of the unisequences, six were shown to be of Peronospora viciae f. sp. pisi origin. The remaining unisequences were subjected to gene ontology analysis and their functions were predicted in silico. Eleven of these unisequences (representing 24 clones) shared significant sequence similarities with Arabidopsis genes known to be involved in downy mildew resistance, including the well-characterised genes RPP5, RPP6 and RPP27. Expression analysis of five selected unisequences by real-time PCR indicated that all five were up-regulated during downy mildew pathogenesis, suggesting a significant role for these genes in the host response to downy mildew infection. [ABSTRACT FROM AUTHOR]