Puccinia coronata f.sp. avenae
Scientific classificationEdit this classification
Domain: Eukaryota
Kingdom: Fungi
Division: Basidiomycota
Class: Pucciniomycetes
Order: Pucciniales
Family: Pucciniaceae
Genus: Puccinia
Species: P. coronata
Variety: P. c. var. avenae
Forma specialis: P. c.  f.sp. avenae
Trionomial name
Puccinia coronata f.sp. avenae

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. 1 2 3 4 5 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. 1 2 3 "Oat crown rust". Cereal Disease Laboratory. United States Department of Agriculture | Agricultural Research Service. Retrieved 19 October 2015.
  3. ↑ 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. 1 2 Dinoor, Amos (February 1977). "Oat crown rust resistance in Israel". Annals of the New York Academy of Sciences. 287 (1): 357–366. Bibcode:1977NYASA.287..357D. doi:10.1111/j.1749-6632.1977.tb34253.x. S2CID 83866651.
  5. 1 2 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. S2CID 22100351.
  6. ↑ 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.
  7. ↑ 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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