Sirodesmin PL levels in culture filtrates of in wild type (wt) and a cpcA -silenced (cpcA-sil) isolate of Leptosphaeria maculans. Cultures were grown for eight days in Tinline media (8d) and the culture filtrate isolated and sirodesmin PL levels were quantified by HPLC. Mycelia were washed then transferred to fresh Tinline medium with water (+H2O) or 5 mM 3AT (+3AT), or Tinline medium with no carbon or nitrogen sources (-C/N) for a further eight days. Culture filtrates from the three treatments (+H2O, +3AT, -C/N) were extracted and sirodesmin PL levels were quantified by HPLC. Values are means ± SE of three independent biological samples. Asterisks mark values that have a significant increase or decrease (p < 0.05) in sirodesmin PL production compared to water controls (+H2O).