Transgenic canola lines expressing pea defense gene DRR206 have resistance to aggressive blackleg isolates and to Rhizoctonia solani

Abstract

We have previously demonstrated that transgenic Brassica napus plants expressing pea DRR206 constitutively are resistant to the hemibiotrophic blackleg fungus, Leptosphaeria maculans isolate PG2. The present work seeks to determine whether DRR206 is effective against a wider range of fungi. Transgenic plants expressing DRR206 exhibit decreased severity of stem canker in adult plants inoculated with aggressive L. maculans isolates PG3 and PG4. Decreased seedling mortality with the biotrophic root pathogen Rhizoctonia solani is also seen. Finally, leaves of DRR206 transgenic plants inoculated with the necrotroph Sclerotinia sclerotiorum show smaller lesions at 48 h after inoculation, leading to a delay, but not a prevention, of disease development. These results demonstrate the effectiveness of DRR206 against several fungal species with three distinct modes of pathogenicity. Although its precise function remains to be determined, a recent report shows that pea DRR206 shares strong amino acid sequence similarity with `dirigent proteins' which couple monolignol radicals to form the lignan (+) pinoresinol.