The GH18 chitinase family. The tree includes GH18 proteins from 23 species: Arabidopsis (AT), rice, Brachypodium (Bradi), sorghum, and poplar, as well as sequences from 13 other eudicots (sugar beet, longleaf ironwood, jelly fig, strawberry, soybean, white lupine, Medicago, a legume, winged bean, ginseng, adzuki bean, cowpea, and grape) and 5 other monocots (bamboo, bread wheat, wild tulip, durum wheat, and maize). The tree was constructed using the Neighbor-Joining method and 1,000 bootstrap replicates. The percent of bootstrap replicates supporting each major branch is indicated. Distances are proportional to the number of amino-acid substitutions per site. Sequences from eudicots are indicated in blue (Arabidopsis with filled triangles, other eudicots with open triangles); sequences from monocots are indicated in red (Brachypodium with filled circles, other monocots with open circles). For clarity, gene names or accession numbers are shown only for Arabidopsis and Brachypodium. Chitinase class designations are listed by each clade and specific XIPs are labeled. For complete branch labels and bootstrap values, see additional file 10.