Effect of Btl19-13 on R. microsporus cell membrane stress tolerance and global gene expression. (A and B) Colony diameter of R. microsporus infected with wild-type Mycetohabitans sp. B13 (WT), B13∆btl19-13 (mutant), or the mutant strain carrying btl19-13 on a plasmid (pBtl19-13). Fungi were grown at 28 °C on half-strength potato dextrose agar without (A) or with (B) 0.005% SDS for 3 and 6 d, respectively. Data shown represent 10 biological replicates for each bacterial genotype and were analyzed by ANOVA with a post hoc Tukey’s test to determine significance as indicated by lowercase letters (P < 0.001). The experiment was repeated twice and yielded similar results. (C) Venn diagram of the genes that were differentially expressed between R. microsporus infected with wild-type B13 or the complement, B13∆btl19-13(pBtl19-13), and the mutant B13∆btl19-13. Differential expression was determined by RNA sequencing. Data were analyzed with DESeq2 (37) using an adjusted P value < 0.05 as the threshold for significance. Three biological replicates were sequenced, each containing tissue from three plates.