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ARS Home » Pacific West Area » Pullman, Washington » WHGQ » Research » Publications at this Location » Publication #339103
Title: Variability of the stripe rust pathogen

Author
item WAN, ANMIN - Washington State University
item WANG, XIAOJIE - Northwest Agriculture And Forestry University
item KANG, ZHENSHENG - Northwest Agriculture And Forestry University
item Chen, Xianming

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 4/14/2017
Publication Date: 7/11/2017
Citation: Wan, A., Wang, X., Kang, Z., Chen, X. 2017. Variability of the stripe rust pathogen. In: Chen, X., Kang, Z., editors. Stripe Rust. Dordrect, The Netherlands: Springer Science. p.35-154.

Interpretive Summary: The stripe rust pathogen is highly variable. The variation has been studied for about 100 years based on virulence, for about 30 years based on molecular markers, and for about 10 years based on genome sequencing and functional genomics. A large number of races have been identified using virulence tests. Such information is essential for developing cultivars with effective resistance to the disease. Molecular characterization of the pathogen has generated data useful in understanding mechanisms of pathogen variation. The high variability of the pathogen is due to its high reproducibility, capability of long-distance dissemination, and ability for adapting to various host species and environments. Among the genetic and evolutionary mechanisms for producing variation, mutation is most important in generating new races and genotypes that are under selection of host species, host cultivars and environments. The pathogen also produces new variants through somatic recombination. Sexual recombination has been recently demonstrated mainly under controlled conditions. Natural reproduction on alternate hosts has been found so far in China, but its role in generating spores and creating new races to attack crop cultivars is still unclear in this country, while ruled out in some other countries. Research on genome sequencing and functional genomics has generated huge data for understanding the pathogen variation and created useful resources for developing new tools for further studying and monitoring the pathogen variation.

Technical Abstract: The stripe rust pathogen, Puccinia striiformis, is highly variable. The variation has been studied for about 100 years based on virulence, for about 30 years based on molecular markers, and for about 10 years based on genome sequencing and functional genomics. Virulence characterization using host differential genotypes has identified a large number of races or pathotypes that overcome race-specific resistance genes in cultivars of wheat and barley crops. Such information is essential for developing cultivars with effective resistance to the disease. Molecular characterization of the pathogen using various marker techniques has generated data that are useful in determination of population structure, identification of pathogen introduction and dissemination and understanding of mechanisms of variation. Molecular characterization has conducted to support findings from virulence tests and/or obtain information that is unable to produce through virulence characterization. The high variability of the stripe rust pathogen is due to its high reproducibility, capability of long-distance dissemination, and ability for adapting to various host species and environments. Among the genetic and evolutionary mechanisms for producing variation, mutation is most important in generating new races and genotypes that are under selection of host species, host cultivars and environments. The pathogen also produces new races and genotypes through somatic recombination. Sexual recombination has been recently demonstrated mainly under controlled conditions in generating variation in races and phenotypes. Natural reproduction on alternate hosts, mainly Berberis spp., has been so far found in China, but its role in generating aeciospores to start stripe rust epidemics on cereal crops and creating new races to attack crop cultivars is still unclear in this country, while ruled out in some other countries. Compared to other fungal pathogens, research on genome sequencing and functional genomics has started relatively late, but recent studies have generated huge data that have helped in understanding the pathogen variation and created useful resources for developing new tools for further studying and monitoring the pathogen variation.