Microarray analysis of Cryphonectria parasitica Ga- and Gbc-signalling pathways reveals extensive modulation by hypovirus infection

Received 18 May 2004 Revised 3 September 2004 Accepted 7 September 2004 Using an established spotted cDNAmicroarray platform, the nature of changes in the transcriptional profiles of 2200 unique genes from the chestnut blight fungusCryphonectria parasitica in response to the absence of either the Ga subunit CPG-1 or the Gb subunit CPGB-1 has been explored. It is reported that 216 transcripts were altered in accumulation in the Dcpg-1 strain and 163 in the Dcpgb-1 strain, with a considerable overlap (100 genes) that were changed in both cases. Of note, these commonly altered transcripts were changed in the same direction in every instance, thus suggesting a considerable redundancy in pathway control or extensive crosstalk. To further knowledge of the potential impact on G-protein-signalling of infection by hypovirus CHV1-EP713, the accumulation of CPG-1 and CPGB-1 was also investigated by Western analysis. It was demonstrated that both signalling components were reduced in abundance to approximately 25% of wild-type levels, while their transcripts were slightly elevated. Comparison of a list of genes with altered expression in the presence of CHV1-EP713 to the data obtained in the absence of either G-protein subunit showed that more than one-half of all the transcripts changed by hypovirus infection were also changed in at least oneG-protein mutant strain, with one-third being changed in both. Significantly, 95% of the co-changed genes were altered in the same direction. These data provide the first evidence for modulation of Gb protein levels as well as the Gbc-signalling pathways by hypovirus infection, and support the hypothesis that modification of G-protein-signalling via both Ga and Gbc provides for a significant contribution to hypovirus-mediated phenotype.