Figure 2: The P. infestans genome shows an unusual distribution of intergenic region lengths.
From: Genome sequence and analysis of the Irish potato famine pathogen Phytophthora infestans
The flanking distance between neighbouring genes provides a measurement of local gene density. P. infestans genes were sorted into two dimensional bins on the basis of the lengths of flanking intergenic distances to neighbouring genes at their 5′ and 3′ ends. a–h, The number of genes in each bin is shown as a colour-coded heat map on orthogonal projection. P. infestans whole-genome analysis (a) shows most genes with intergenic regions between 20-bp and 3-kb long, as well as sets of genes flanked by one or two intergenic region(s) between 5 kb and 36 kb. Comparison with other Phytophthora genomes (b, c) indicates that this separation is observed in P. infestans but not the other two sequenced genomes. Genes in collinear blocks (d) and the core orthologue clusters (e) have primarily shorter intergenic distances, whereas genes outside of collinear blocks (f) reside mostly in gene sparse regions. Genes belonging to the RXLR (g) and Crinkler (CRN) (genes and pseudogenes) (h) effector families have flanking intergenic distances among the longest. Genes found at the ends of scaffolds and hence lacking neighbouring genes were necessarily excluded.
