Transformation Of Sheath Blight Resistance Genes Into Maize And Characterization Of Its Progenies

Sheath blight is one of the maize common fungal diseases caused by Rhizoctonia solani and threatens maize production in China.There is no known germplasm that are resistant to sheath blight that can be used for classic breeding.In this study,three exogenous defense-related genes including tomato?Lycopersicum esculentum?transcription factor Pti4 gene,tobacco?Nicotiana tabacum??-1,3-glucanase gene NtGlu and radish?Raphanus sativus L?antifungal peptide gene Rs-AFP2 were transformed into maize.The transgenic maize plants and its progenies were characterized for the transgene integration,expression,transmission and the disease resistance.Immature embryos of maize HiII or A188 are used for maize transformation.Both gene particle bombardment and agrobacterium-mediated transformation method were applied in our research.The NtGlu expression vector and Pti4-Rs-AFP2 co-expression vector with Bar gene serves as a selection marker were successfully transformed into maize.Four NtGlu transgenic lines and two co-expression Pti4 and Rs-AFP2 transgenic lines were obtained using gene particle bombardment transformation with HiII.Every generation of transgenic plants were backcrossed to Zheng58 and T₄ generation plants were evaluated for its blight sheath disease resistance.Two NtGlu transgenic lines were obtained using agrobacterium-mediated transformation method with A188.T₀ plants were backcrossed to Zheng58 and T₂ generation were harvested.Molecular characterization of the T₄ lines demonstrated that the foreign genes have been successfully transmitted to the forth generation and stably expressed.The T₄ plants were evaluated for the herbicide basta resistance by staining with 0.02%Basta.The results showed that the ratio of resistance plants to non-resistance plants is about 1:1.The detached leaves of basta resistance plants and WT plants were inoculated with Rhizoctonia solani and the relative lesion area and electric conductivity were measured.The results showed that both NtGlu expressing plants and co-expressing Pti4 and Rs-AFP2 plants had significantly higher resistance to maize sheath blight compared with WT control.Furthermore,the relative activity of?-1,3-glucanase in NtGlu transgenic lines is significantly increased than wild type.