Diversity in Puccinia graminis f. sp. avenae and its impact on oat cultivar response in South Africa
Puccinia graminis f. sp. avenae (Pga) samples were collected from cultivated oat (Avena sativa L.) in trial plots and commercial fields and from wild oat (Avena spp.) during the 2016 and 2017 seasons. Field samples were purified through selection of single pustule isolates and subsequent urediniospore increases using the susceptible cultivar Swan. For race phenotyping, a set of 12 international differential lines was used that resulted in the identification of races RSJ, RJS and RJJ. Race RSJ was the most prevalent (60% of isolates) followed by races RJS (34%) and RJJ (6%). These races varied in virulence for Pg6 and Pg12, with no avirulence recorded for Pg1, 2, 4, 8, 9, 13 and Pg15 and no virulence for Pg3, 10 and Pg16. Seedling infection types of 32 oat cultivars to the three described races showed compatible phenotypes for all cultivars towards at least one of the races. Moderate levels of adult plant resistance against races RJS and RSJ were recorded for seven cultivars during field tests in 2017 and 2018. Thirteen microsatellite markers used to assess genetic variability amongst twenty four field isolates revealed three sub-populations of which only one correlated with the race phenotype. The results contributed to our understanding of the diversity of the Pga population in South Africa, including useful resistance sources and cultivar responses.
KeywordsPuccinia graminis f. sp. avenae Oat stem rust Pathogenic variation Cultivar response
Producers and dealers of oat seed in SA (Agricultural Research Council – Small Grain, Agricol, Barenbrug, Capstone, K2, Pannar Seed and Sensako) are acknowledged for making seed of their cultivars available. Pannar Seed is thanked for the maintenance of field trials. Dr. Tom Fetch (Agriculture and Agri-Food Canada) and Prof Robert Park (Plant Breeding Institute, The University of Sydney) are thanked for providing seed of differential lines.
The National Research Foundation (SARChI chair UID 8464) is thanked for funding.
Compliance with ethical standards
We hereby declare that our submission is in compliance with the ethical responsibilities and standards of the EJPP as well as those of the University of the Free State.
Conflict of interest
The authors declare that they have no conflict of interest.
- DAFF. (2017). A profile of the south African oats market value chain. Forestry and Fisheries, Pretoria, South Africa: Department of Agriculture https://www.nda.agric.za/doaDev/sideMenu/Marketing/Annual%20Publications/Commodity%20Profiles/field%20crops/Oats%20Market%20Value%20Chain%20Profile%202017.pdf. Accessed 9 April 2017
- Excoffier, L., Laval, G., & Schneider, S. (2005). Arlequin ver 3.0: An integrated software package of population genetics data analysis. Evolutionary Bioinformatics Online, 1, 47–50.Google Scholar
- Meldrum, S., & Oates, J. D. (1997). Oat stem rust. Annual report, Cereal Rust Survey 1996–97 (pp. 11–13). Cobbity, University of Sydney, Camden: Plant Breeding Institute.Google Scholar
- Neethling, J. H. (1932). Wheat varieties in South Africa - their history and development until 1912. Science bulletin no. 108, Department of Agriculture, Union of South Africa, p 1-40.Google Scholar
- Perrier, X., Flori, A., & Bonnot, F. (2003). Data analysis methods. In P. Hamon, M. Seguin, X. Perrier, & J. C. Glazmann (Eds.), Genetic diversity of cultural tropical plants (pp. 43–76). Enfield, UK: Science Publishers.Google Scholar
- Roelfs, A. P., Singh, R. P., & Saari, E. E. (1992). Rust diseases of wheat: Concepts and methods of disease management. Mexico: CIMMYT.Google Scholar
- Saghai-Maroof, M. A., Soliman, K. M., Jorgensen, R. A., & Allard, R. W. (1984). Ribosomal DNA spacer-length polymorphisms in barley: Mendelian inheritance, chromosomal location and population dynamics. Proceedings National Academy Science USA, 81, 8014–8018.Google Scholar
- Sambrook, J., Fritsch, E. F., & Maniatis, T. (1989). Molecular cloning, a laboratory manual (2nd ed.). New York: Cold Spring Harbor Laboratory Press.Google Scholar
- Sihlobo, W. (2017). Global view on oat production. Agricultural business chamber e-newsletter 17–03, Pretoria, South Africa. https://myemail.constantcontact.com/Agbiz-eNewsletter%2D%2D27-January-2017.html?soid=1102135630669&aid=_Bx5NEO49vc (accessed 9 April 2019).
- Visser, B., Meyer, M., Park, R. F., Gilligan, C. A., Burgin, L. E., Hort, M. C., Hodson, D. P., & Pretorius, Z. A. (2019). Microsatellite analysis and urediniospore dispersal simulations support the movement of Puccinia graminis f. sp. tritici from southern Africa to Australia. Phytopathology, 109, 133–144.CrossRefGoogle Scholar