Biotransformation of the Brassica Phytoalexin Brassicanal A by the Blackleg Fungus

Abstract

The biotransformation of the brassica phytoalexin brassicanal A by the blackleg fungus [ Leptosphaeria maculans (Desm.) Ces. et de Not., asexual stage Phoma lingam (Tode ex Fr.) Desm] was investigated. Three main biotransformation products were detected and isolated; their chemical structures were determined by spectroscopic methods and concomitant synthesis. Additionally, the antifungal activities of brassicanal A and its biotransformation products were compared. Overall, the biotransformation pathway suggests that the blackleg fungus has enzymes to carry out this biotransformation different from those involved in the biotransformation of the brassica phytoalexin brassinin. Keywords: Blackleg fungus; brassicanal A; brassinin; canola; Leptosphaeria maculans; Phoma lingam; phytoalexin; rapeseed