Enhanced resistance to gray mold (Botrytis cinerea) in transgenic potato plants expressing thionin genes isolated from Brassicaceae species

Abstract

Five novel thionin genes have been isolated from three Brassicaceae species, Brassica oleracea var. acephala, Nasturtium officinale, and Barbarea vulgaris. Comparison of the deduced amino acid sequences shows that these thionin proteins share seven highly conserved cysteine residues. These five thionin genes were, respectively, inserted between cauliflower mosaic virus 35S promoter and nopaline synthase terminator in a binary vector pEKH2. Transgenic potato plants were generated through Agrobacterium-mediated transformation methods. Southern blot analysis of transgenic potato plants indicated successful integration with varying copy number of the thionin genes into the plant genomes. Expressions of thionin transgenes in the transgenic plants were confirmed by RT-PCR and their protein products were immunologically detected by western blot analyses. Antifungal assay using detached leaves from transgenic lines expressing either of the thionin genes showed similar levels of enhanced resistance to Botrytis cinerea as compared to those of non-transformed control plants. Novel thionin genes isolated in this study are probably useful tools to produce transgenic plants resistant to various phytopathogens. © 2012 The Japanese Society for Plant Cell and Molecular Biology.