Phylogenetic tree of NLR genes in wheat. Cloned R genes were added to the tree. Specific clades are marked according to certain characteristics discussed in the main text: members of clades Intron1, Intron2, and Intron3 share characteristic intron/exon structure. Clades ID1 to ID5 are enriched for members with integrated domains. Members of clade NB-ARC have a truncated NB-ARC domain preceding a complete NB-ARC domain. Clade Helper is enriched for NLRs being hypothesized to be helpers. An interactive version of this figure is available at https://itol.embl.de/shared/steuernb.