FIG 2.

Generation of ascochitine-negative mutants. (A) The pksAC coding sequence of A. fabae isolate AF1 (WT) was replaced with a hygromycin phosphotransferase gene cassette (hph). Gene replacement was confirmed by PCR; the primer pair is indicated by arrows. (B) A front view of the WT and ΔpksAC (KO) strains after 10 days of hyphal growth on potato dextrose agar is shown in the top panel; reverse views of hyphal growth after 20 days are shown in the middle and bottom panels. (C) UV-visible light (UV-Vis) chromatograms (left panels) and selected ion mass chromatograms (right panels) of WT (upper panels) and KO (bottom panels) culture extract. Peaks characteristic of ascochitine and its derivative ascochital are indicated with arrows where present. Denoted is the ascochitine observed m/z; for reference, the m/z calculated for C₁₅H₁₆NaO₅ [M+Na]⁺ is 299.0895.