Production of the toxin sirodesmin PL by Leptosphaeria maculans during infection of Brassica napus

Abstract

Sirodesmin PL is a non-host-selective phytotoxin produced by Leptosphaeria maculans, which causes blackleg disease of canola (Brassica napus). Previous studies have shown that sirodesmin PL biosynthesis involves a cluster of 18 co-regulated genes and that disruption of the two-module non-ribosomal peptide synthetase gene (sirP) in this cluster prevents the production of sirodesmin PL. Loss of sirodesmin PL did not affect the growth or fertility of the sirP mutant in vitro, but this mutant had less antibacterial and antifungal activity than the wild-type. When the sirP mutant was inoculated on to cotyledons of B. napus, it caused similar-sized lesions on cotyledons as the wild-type isolate, b..