Biology:Puccinia coronata f. sp. avenae
Template:Infraspeciesbox special
Puccinia coronata f. sp. avenae is the variation (forma specialis, f. sp.) of the crown rust fungus (Puccinia coronata) which infects oat plants (Avena sativa).[1] Almost every growing region of oat has been affected by this pathogen at one point or another.[2] During particularly bad epidemics, the worldwide crop yields have been reduced by up to 40%.[2] One reason why Pca has such a prominent effect is that the conditions which favor oat production also favor the growth and inoculation of the rusts: Meaning that years in which the highest yields of crops are expected are the same years in which losses are the highest as well.[2] Pca urediniospores germinate the best at temperature between 10–30 °C (50–86 °F) with germ-tube growth optimized at 20 °C (68 °F).[3]
The virulence of Pca and the resistance of wild oat plants is a highly studied topic. It seems that the resistance level of the oat plant is dependent upon which race of Pca is acting on it; the virulence of the fungal pathogen also seems to depend upon which strain the strain of oat being attacked.[4] There are most likely multiple traits that control both virulence and resistance which suggests a very interactive host-parasite coevolution.[4] A few specific loci have been found to confer resistance such as Pca which conferred a dominant, resistant phenotype to nine different isolates of P. coronata.[5] An additional isolate of P. coronata was also resisted, although another, un-linked gene may be involved which correlates the theory that resistance and virulence in A. sativa are controlled by multiple genes.[5] Some studies suggest that the responses are dependent upon the physiological race of the rust involved due to mutations that arise in separate races.[6]
One way in which the expression of certain genes has been found to combat Pca is through the production of avenalumins.[1] Avenalumins are antimicrobial compounds which inhibit hyphal growth, thus preventing P. coronata from spreading.[1] Avenalumins are only found in infected areas of plants and nowhere else.[1] The production of avenalumins is regulated by some of the same genes that have been found to confer resistance in certain lines of oats, thus indicating their importance in resistance.[1] In addition to total resistance to specific races, in such cases as the production avenalumins, partial or horizontal resistance provides a way to reduce the effect of P. coronata.[7]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 Mayama, S.; Matasuura, Y; Iida, H; Tani, T (March 1982). "The role of avenalumin in the resistance of oat to crown rust, Puccinia coronoata f. sp. avenae". Physiological Plant Pathology 20 (2): 189–199. doi:10.1016/0048-4059(82)90084-4.
- ↑ 2.0 2.1 2.2 "Oat crown rust". United States Department of Agriculture | Agricultural Research Service. http://www.ars.usda.gov/Main/docs.htm?docid=9919. Retrieved 19 October 2015.
- ↑ Kochman, J.K.; Brown, J.F. (March 1976). "Effect of temperature, light and host on prepenetration development of Puccinia graminis avenae and Puccinia coronata avenae". Annals of Applied Biology 82 (2): 241–249. doi:10.1111/j.1744-7348.1976.tb00559.x.
- ↑ 4.0 4.1 Dinoor, Amos (February 1977). "Oat crown rust resistance in Israel". Annals of the New York Academy of Sciences 287 (1): 357–366. doi:10.1111/j.1749-6632.1977.tb34253.x. Bibcode: 1977NYASA.287..357D.
- ↑ 5.0 5.1 Rayapati, P.J.; Greogry, J.W.; Lee, M; Wise, R.P. (December 1994). "A linkage map of diploid Avena based on RFLP loci and a locus conferring resistance to nine isolates of Puccinia coronata var. 'avenae'". Theoretical and Applied Genetics 89 (7): 831–837. doi:10.1007/BF00224505. PMID 24178091.
- ↑ Dumsday, J.L; Smith, K.F.; Forster, J.W.; Jones, E. S. (October 2003). "SSR-based genetic linkage analysis of resistance to crown rust (Puccinia coronata f. sp. lolii) in perennial ryegrass (Lolium perenne)". Plant Pathology 52 (5): 628–637. doi:10.1046/j.1365-3059.2003.00884.x.
- ↑ Briere, S.C.; Kushalappa, A.C.; Mather, D.E (1994). "Screening for Partial Resistance to an Isolate of Crown Rust (Puccinia coronata f. sp. avenae) Race 264 in Oat Cultivars and Breeding Lines". Canadian Journal of Plant Pathology 16 (1): 49–55. doi:10.1080/07060669409500787.
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