Pathways of infection of Brassica napus roots by Leptosphaeria maculans

Abstract

• Infection of Brassica napus cotyledons and leaves by germinating ascospores of Leptosphaeria maculans leads to production of leaf lesions followed by stem cankers (blackleg). Leptosphaeria maculans also causes root rot but the pathway of infection has not been described. • An L. maculans isolate expressing green fluorescent protein (GFP) was applied to the petiole of B. napus plants. Hyphal growth was followed by fluorescence microscopy and by culturing of sections of plant tissue on growth media. Leptosphaeria maculans grew within stem and hypocotyl tissue during the vegetative stages of plant growth, and proliferated into the roots within xylem vessels at the onset of flowering. Hyphae g..