Molecular Characterization of the Broad-Spectrum Resistance to Powdery Mildew Conferred by the Stpk-V Gene from the Wild Species Haynaldia villosa
L. XING (1), C. qian (2), A. cao (1), J. xiao (1), X. wang (1), P. chen (1) (1) National Key Laboratory of Crop Genetics and Germplasm Enhancement , Nanjing Agricultural University/JCIC-MCP, China; (2) Laboratory of Forage Breeding, Institute of Animal Science, Jiangsu Academy of Agricultural Sciences, China

A key member of the Pm21 resistance gene locus derived from Haynaldia villosa was shown to confer high level and broad-spectrum resistance to wheat powdery mildew. In this study, to further investigate the mechanism of Stpk-V in regulating powdery mildew resistance at the molecular level, transcriptome analysis using digital gene expression was performed to profile gene expression patterns in Stpk-V transgenic plants and its recipient Yangmai158 upon Bgt infection. The detailed histochemical observations of the Bgt infected cells were also conducted in both materials. The ROS pathway, JA pathway and some PR proteins associated with SA pathway were activated at early stage after Bgt infection in both the resistant Stpk-V transgenic plants and susceptible recipient plants Yangmai158, however, the continuously activation of them were retained in transgenic plants, which indicated that the sustained activation of these pathways mediated by Stpk-V were critical for the regulation of hypersensitive response leading to the Pm resistance in the Stpk-V transgenic plants. We also studied the evolution of Stpk-V in the grass family and its function in resistance to barley and Arabidopsis powdery mildew. The evolutionary study showed that Stpk-V orthologous genes in the representative grass species are all located on homologous group six chromosomes, which indicated that Stpk-V is a highly conserved and ancient gene in the grasses. Transient over-expression of Stpk-V in barley could dramatically decrease the haustorium index of the barley powdery mildew pathogen Bgh, however, transgenic Arabidopsis plants expressing Stpk-V did not show enhanced resistance to Arabidopsis powdery powdery mildew disease. Our results enabled a better understanding of the resistance mechanism mediated by Stpk-V, and established a solid foundation for its use in cereal breeding.

Abstract Number: P18-695
Session Type: Poster