Highlights - Mapping and Cloning Disease Resistance Genes in Barley and Wheat

Principal Investigator: Shaobin Zhong (Plant Pathology, North Dakota State University)

Dr. Zhong’s research program focuses on genetic and molecular mechanisms of plant-pathogen interactions in barley and wheat. His lab uses genetic mapping and genome sequencing approaches to identify and clone genes related to resistance to spot blotch in barley and Fusarium head blight in wheat. These diseases significantly reduce yield and grain quality of the two crops. Use of resistance is the most effective and environmentally sound approach to manage the diseases.

Zhong, Fig. 1

The group has mapped one gene (Scs6) conferring susceptibility to spot blotch to the powdery mildew resistance locus (Mla) on chromosome 1H in barley cultivar Bowman. To clone the Scs6 gene, mutants with loss of function in Scs6 were generated. The 1H chromosomes from Bowman and the mutants were isolated by chromosome sorting technology and were sequenced. The candidate gene controlling the disease susceptibility has been identified and confirmed by gene transformation and functional characterization. Another gene (Rbs7) controlling resistance to spot blotch was mapped on chromosome 6H in a barley line. This gene will be isolated using the same approach as used for isolating Scs6. 

The group is also finely mapping and isolating a Fusarium head blight resistance gene located on chromosome 5A in the wheat line PI 277012. Having a whole genome sequence is essential for cloning the target gene. However, sequencing a whole wheat genome is a huge task and very challenging because wheat genome has a very large genome size (tens of gigabytes) and contains over 80% repetitive sequences. To reduce the complexity, the 5A chromosome from PI 277012 and a susceptible wheat line has been isolated and sequenced in a collaboration with a research team in Czech Republic. Genome sequence analysis and comparison will allow for identification of the candidate genes responsible for resistance to the FHB disease.  

CCAST’s compute clusters and data storage systems are essential for the group to accomplish the research goal and objectives for gene isolation and functional characterization. Members of the group use a number of bioinformatics tools for gene mapping, genome sequence assembly, gene annotation, genome structure comparison and analysis.

The group’s current projects are funded by the U.S. Wheat and Barley Scab Initiative sponsored by USDA-ARS and North Dakota Wheat Commission.

References
[1] Wang, R., Leng, Y., Zhao, M., and Zhong, S. 2019. Fine mapping of a single dominant gene for resistance to spot blotch caused by a new pathotype of Bipolaris sorokinianan in barley. Theor. Applied. Genet. 132:41–51.
[2] Zhao, M., Leng, Y., Chao, S., Xu, S. S., and Zhong, S. 2018. Molecular mapping of QTL for FHB resistance introgressed into durum wheat. Theor. Applied. Genet. 131:1939-195.
[3] Leng, Y., Zhao, M., Wang, R., Steffenson, B. J., Bruggeman, R. S., and Zhong, S. 2018. The gene conferring susceptibility to spot blotch caused by Cochliobolus sativus is located at the Mla locus in barley cultivar Bowman. Theor. Applied. Genet. 131:1531-1539.
[4] Zhao, M., Wang, G., Leng, Y., Wanjugi, H., Xi, P., Grosz, M. D., Pitkin, J., Mergoum, M., and Zhong, S. 2018. Molecular mapping of Fusarium head blight resistance in ND2710. Phytopathology 108:972-979.

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