LYM1 and LYM3 mediate PGN sensitivity and immunity to bacterial infection. (A and B) Analysis of global gene expression induced by PGN treatment in wild type and lym1-1 (A) and lym3-1 (B) mutants. Leaves of adult plants were treated with water or 100 μg/mL of PGN for 6 h, and extracted RNA was used for microarray analyses. Significantly induced or suppressed genes by either treatment were selected (750 genes; Storey's q value < 0.1), and the log2 ratios of transcript levels in PGN-treated plants versus water controls were plotted. Linear regression lines indicate gene expression levels in Col-0 (red) or mutants (black). (C) lym3 lym1 double mutants are as supersusceptible to bacterial infection as lym1-1 and lym3-1 single mutants. Growth of Pto DC3000 in lym1-1 and lym3-1 plants and two independent lym3 lym1 double-mutant lines (a, b) after infiltration of 104 colony-forming units/mL. Data represent means ± SD of six replicate measurements per genotype per data point. Statistical significance compared with wild type is indicated by asterisks (*P ≤ 0.1, **P ≤ 0.05, Student's t test). One of three independent experiments is shown.