Differential induction of two potato genes, Stprx2 and StNAC, in response to infection by Phytophthora infestans and to wounding

To find out more about the interaction between potato and Phytophthora infestans at the molecular level, we screened for genes induced early after infection using mRNA differential display. Among the twenty cDNA clones recovered in the screen, two were found to represent plant genes whose transcript levels increased during infection of intact plants. These two genes differed strikingly in their response to wounding. Stprx2, a putative peroxidase, responded slowly and transiently to wounding, and its expression pattern was similar to that of gst1, a well-described pathogen-induced gene of potato. The second gene, StNAC, was induced rapidly and strongly after wounding but not systemically. Transcript levels reached a maximum after around 1 h and returned to basal levels after ca. 24 h. StNAC has strong similarity to the ATAF subfamily of NAC domain proteins, a large family of putative transcriptional activators. Arabidopsis ATAF1 and ATAF2 were also shown to be induced by wounding. This implies that the ATAF genes are not merely structurally similar but also share a conserved role in stress responses.