Induction of putative pathogenicity-related genes in Verticillium dahliae in response to elicitation with potato root extracts

Verticillium dahliae is the main pathogen causing Verticillium wilt in potato. Management of this vascular disease is very challenging due to the soilborne nature of the pathogen. A better understanding of the molecular host–pathogen interactions is important for the development of novel strategies to control Verticillium wilt. In this pathosystem, the disease cycle starts with stimulation and germination of the V. dahliae microsclerotia through host root exudates. The present study reports on the use of potato root extracts derived from a susceptible (Kennebec) and a moderately resistant (Ranger Russet) cultivar to elicit pathogenicity-related genes in highly and weakly aggressive isolates of V. dahliae. Using a combined approach of subtractive hybridization and cDNA-AFLP, 573 transcripts differentially accumulated in one or the other isolate in response to root extracts were detected. Sixteen primer combinations representing EcoRI/MseI AFLP primers + A, T, C, or G were used to provide a complete coverage of the subtractive hybridization products. The detected differentially expressed transcripts in the highly and weakly aggressive isolates were 301 and 272, respectively. Among the amplified transcripts, 185 were recovered from the PAGE gel then re-amplified by PCR and further sequenced. BLAST search against the NCBI, the Broad Institute V. dahliae genome, and V. dahliae ESTs collection COGEME databases showed that some of the differentially expressed transcripts matched with known sequences, with assigned functions in V. dahliae such as polygalacturonases or with conserved hypothetical proteins. The remaining sequences had no match in these databases. The results are discussed based on the potential involvement of these genes in V. dahliae's pathogenesis.

► Root extracts from potato elicited pathogenicity-related genes in V. dahliae.
► Differentially induced transcripts based on subtractive hybridization/cDNA-AFLP.
► Full coverage of differentially expressed transcripts identified 301 and 272 induced transcripts in highly and weakly aggressive V. dahliae isolates, respectively.
► Some transcripts with putative pathogenicity-related functions in V. dahliae were detected.