The interplay of pathogens, microRNAs, and regulation of resistance gene transcript abundance in tomatoes
L. ROSE (1), S. de Vries (1), T. Kloesges (1), J. von Dahlen (1), A. Kukuk (1) (1) University of Duesseldorf, Germany

Plant genomes typically contain hundreds of R-genes, most of which are under some form of negative regulation. The recent discovery of a group of miRNAs that specifically target R-genes has opened the door to discovering which set of R-genes are targeted by these miRNAs and how this form of regulation is modified during pathogen infection. We have investigated the evolutionary history of members of the miR482 gene family in the Solanaceae, with a special focus on the group of wild tomatoes and their close relatives within the genus Solanum. The genomes of the tomato species typically contain seven different, but evolutionarily related, miR482 genes. These genes are predicted to target approximately 20% of the tomato R-gene repertoire. To determine how the abundance of miRNA and their predicted R-gene targets is affected during pathogen infection, we used qPCR to quantify miRNA and R-gene transcript abundance on three different tomato species, S. lycopersicum, S. pimpinellifolium and S. arcanum at six different time points during infection by the oomycete pathogen, Phytophthora infestans. The use of multiple host and pathogen genotypes allowed us to evaluate the effect of genotype on miRNA and R-gene abundance. Pathogen isolates showed variation in their ability to spread and transition from biotrophy to necrotrophy on the different host species. As a consequence, the dynamic of miRNA transcript abundance also differed between hosts depending upon pathogen isolate. Experiments are currently underway to investigate how differences in miRNA abundance correlate with the transcript abundance of the predicted R-gene targets and how modification of miRNA abundance during pathogen infection affects the outcome of this host-parasite interaction.


Abstract Number: C8-1
Session Type: Concurrent