13 thaxtomin A-resistant mutants were isolated from a screen of 10⁷ mutants.

A: Wild type spores from a cross between Tak-1 and Tak-2 grown for 14 days on solid medium supplemented with 0.1% DMSO or 5 μM thaxtomin A (TXTA), and UV-B mutagenesis selection plates supplemented with 5 μM thaxtomin A showing 14-day old thaxtomin A-resistant mutants Mpthar1 and Mpthar2 surrounded by dead mutagenized thaxtomin A-sensitive spores. Images were taken with a Leica DFC310 FX stereomicroscope. Scale bars represent 2 mm and were added in Inkscape v1.0.1. B: Wild type (Tak-1 and Tak-2) and Mpthar gemmalings grown for 12 days on solid medium supplemented with 0.1% DMSO or 5 μM thaxtomin A. Images were taken with a Keyence VHX-7000 and the maximum pixel value was adjusted to 188 in ImageJ. Scale bars represent 2 mm and were added in Inkscape v1.0.1. C: Gemmae from wild type lines (Tak-1 and Tak-2) and from Mpthar lines were plated on solid medium supplemented with DMSO (blue bars) or 5 μM thaxtomin A (orange bars) and grown for 21 days (n = 3–13) (Tab E in S1 Table). Error bars represent ± standard deviation. Stars represent the level of significance (as determined by Student’s t-tests) of the difference between mutant and control lines subjected to the same treatment (comparison to Tak-1 in red and Tak-2 in green), or between individuals of the same genotype subjected to different treatments (black): * = p < 0.05, ** = p < 0.01, *** = p < 0.001.