Browsing by Author "Zhang, Peng"

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Stem rust resistance in wheat is suppressedby a subunit of the mediator complex
(2020-02) Hiebert, Colin W.; Moscou, Matthew J.; Hewitt, Tim; Steuernagel, Burkhard; Hernandez-Pinzon, Inma; Green, Phon; Pujol, Vincent; Zhang, Peng; Rouse, Matthew N.; Jin, Yue; McIntosh, Robert A.; Upadhyaya, Narayana; Zhang, Jianping; Bhavani, Sridhar; Vrana, Jan; Karafiatova, Miroslava; Huang, Li; Fetch, Tom; Dolezel, Jaroslav; Wulff, Brande B. H.; Lagudah, Evans; Spielmeyer, Wolfgang
Stem rust is an important disease of wheat that can be controlled using resistance genes. The gene SuSr-D1 identified in cultivar ‘Canthatch’ suppresses stem rust resistance. SuSr-D1 mutants are resistant to several races of stem rust that are virulent on wild-type plants. Here we identify SuSr-D1 by sequencing flow-sorted chromosomes, mutagenesis, and map-based cloning. The gene encodes Med15, a subunit of the Mediator Complex, a conserved protein complex in eukaryotes that regulates expression of protein-coding genes. Nonsense mutations in Med15b.D result in expression of stem rust resistance. Time-course RNAseq analysis show a significant reduction or complete loss of differential gene expression at 24 h post inoculation in med15b.D mutants, suggesting that transcriptional reprogramming at this time point is not required for immunity to stem rust. Suppression is a common phenomenon and this study provides novel insight into suppression of rust resistance in wheat.
Wheat mutant MNR220 delays haustoria formation during leaf rust pathogenesis at the seedling stage
(2016-09) Talajoor, Mina R.; Wang, Xiaojing; Zhang, Hongtao; Zhang, Peng; Bhavani, Sridhar; Tabe, Linda; Lagudah, Evans; Huang, Li
This study reports further characterization of the defence mechanism of an EMS-induced mutant (MNR220) that displays enhanced resistance to leaf rust, stem rust, stripe rust and powdery mildew diseases. The broad-spectrum resistance of the mutant was characterized by a microscopy study and additional race screenings of two rust pathogens. The mutant displayed less disease severity in response to all the races tested, when compared with the wild-type. The microscopy study of the pathogenesis of a leaf rust race PBJJG on the mutant revealed that the resistance was first evident at the pre-haustorial stage; formation of haustoria was significantly delayed or inhibited in the mutant compared with the wild-type. The mutant displayed microscopic level of cell death even in the absence of any pathogens. These findings suggest that MNR220 mediates a spontaneous cell death that delays the infection process by delaying haustoria formation of the pathogen.