a Maximum likelihood phylogeny of KAI2 homologues in the Brassicaceae, based on nucleotide data. Node values represent bootstrap support from 100 replicates. A eu-KAI2 sequence from Gossypium raimondii (Malvaceae) serves as an outgroup. Tree shown is a subset of a larger phylogeny in Supplementary Fig. 2. b Transcript levels of the three BtKAI2 homologues in B. tournefortii seeds imbibed for 24 h (left) and 4-day-old seedlings (right) treated with 0.1% acetone (mock) or with 1 µM KAR1 for 24 h. c, d Seedling and rosette phenotypes of two independent transgenic lines of Arabidopsis homozygous for KAI2pro:GFP-BtKAI2 transgenes. Seedlings were 7 days old and rosettes 22 days old. Scale bars: 5 mm c; 50 mm d. e Immunoblots of soluble proteins challenged with antibodies against KAI2 (upper panel), GFP (middle panel) or actin as a loading control (lower panel). Anti-KAI2 detects both the native AtKAI2 protein (30 kDa) and the GFP-BtKAI2 fusion proteins (58 kDa) but detects BtKAI2b relatively poorly. Non-specific bands are marked with asterisks. Protein was isolated from pools of ∼50 7-day-old seedlings. Source data are provided as a Source Data file.