Whole-genome protein sequences from Arabidopsis, Populus, Vitis, Glycine, Oryza, Brachypodium, Sorghum and Zea were merged and searched against themselves for homology using BLASTP with an E-value cutoff of 10−5. Default parameters of OrthoMCL (50 (link)) were used. The combination of OrthoMCL intermediate files ‘orthologs.txt’ and ‘coorthologs.txt’ (generated by orthomclDumpPairsFiles) was used as the whole set of ortholog pairs.