The researchers studied how genes related to responding to pathogens are organized in the genome of Arabidopsis thaliana. They used computer analysis to identify clusters of non-responsive genes scattered throughout the plant's chromosomes. By analyzing the expression levels of two clusters during infection with cucumber mosaic virus, they found that these genes were significantly activated in the resistant ecotype of the plant. Additionally, they discovered a link between a specific histone modification and the regulation of genes within these clusters. Overall, the study shows that pathogen response genes in Arabidopsis thaliana can be clustered and co-regulated.