Dr. Shahryar Kianian: Genomics Provides new Tools in the Battle Against Cereal Diseases
Dr. Shahryar Kianian, Research Leader at the Agricultural Research Service’s (ARS) Cereal Disease Laboratory in St. Paul, MN spoke at University of Maryland, College Park on March 2, 2017 about the lab’s ongoing work to reduce losses to cereal diseases. Leaf and stem rusts of wheat, oat, and barley and Fusarium head blight (FHB) of wheat and barley are serious fungal diseases that can reduce yields or make crops unusable. In years with major outbreaks, these diseases have caused crop losses of as much as 75% for the small grains they affect1. The Cereal Disease Lab studies the genetics of the pathogens, the crops they affect, and the alternate hosts (e.g. barberry for wheat rust). The Cereal Disease Lab also monitors the populations and severity of these diseases within the United States and internationally.
Current management methods include chemical fungicides and the use of genetically resistant crop varieties. Unfortunately, the pathogens adapt quickly (generally 2-5 years depending on the disease) to overcome widely used resistant genes. Past efforts to break disease cycles by eradicating alternate hosts only had limited success2, mainly because fungal spores arrive seasonally via air currents.
Genomic methods are the key to maintaining defenses against cereal diseases. ARS research has expanded the arsenal of naturally-occurring resistance genes against specific races of cereal diseases. Dr. Kianian and his colleagues also hope to enhance crop resistance by pyramiding resistance genes, and by making use of “slow rusting genes, ” which significantly reduce but do not entirely eliminate pathogens, for example, in oat, Dr. Kianian’s particular area of expertise. Threats to global food security, such as the African wheat rust strain Ug99, which has adapted to overcome most known resistance genes against wheat rust necessitate international cooperation on monitoring and research. The growing understanding of the genetics behind pathogen virulence and crop resistance could potentially lead to new forms of resistance to these diseases, but such approaches have challenges of their own, related to the regulation and marketing of transgenic crops.
2) Peterson, P. D., Leonard, K. J., Roelfs, A. P., and Sutton, T. B. 2005. Effect of barberry eradication on changes in populations of Puccinia graminis in Minnesota. Plant Dis. 89:935-940.
3) Chen, X., Faris, J.D., Hu, J. et al. Saturation and comparative mapping of a major Fusarium head blight resistance QTL in tetraploid wheat. Mol Breeding (2007) 19: 113. doi:10.1007/s11032-006-9049-7