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Diversity in the sunflower: Puccinia helianthi pathosystem in Australia

Sendall, B.C. and Kong, G.A. and Goulter, K.C. and Aitken, E.A.B. and Thompson, S.M. and Mitchell, J.H.M. and Kochman, J.K. and Lawson, W. and Shatte, T. and Gulya, T.J. (2006) Diversity in the sunflower: Puccinia helianthi pathosystem in Australia. Australasian Plant Pathology, 3 (1). pp. 35-40.

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Article Link(s): http://dx.doi.org/10.1071/AP06071

Organisation URL: http://www.australasianplantpathologysociety.org.au/
Publisher URL: http://www.publish.csiro.au/home.htm

Abstract

Sunflower rust caused by Puccinia helianthi is the most important disease of sunflower in Australia with the potential to cause significant yield losses in susceptible hybrids. Rapid and frequent virulence changes in the rust fungus population limit the effective lifespan of commercial cultivars and impose constant pressure on breeding programs to identify and deploy new sources of resistance. This paper contains a synopsis of virulence data accumulated over 25 years, and more recent studies of genotypic diversity and sexual recombination. We have used this synopsis, generated from both published and unpublished data, to propose the origin, evolution and distribution of new pathotypes of P. helianthi. Virulence surveys revealed that diverse pathotypes of P. helianthi evolve in wild sunflower populations, most likely because sexual recombination and subsequent selection of recombinant pathotypes occurs there. Wild sunflower populations provide a continuum of genetically heterogeneous hosts on which P. helianthi can potentially complete its sexual cycle under suitable environmental conditions. Population genetics analysis of a worldwide collection of P. helianthi indicated that Australian isolates of the pathogen are more diverse than non-Australian isolates. Additionally, the presence of the same pathotype in different genotypic backgrounds supported evidence from virulence data that sexual recombination has occurred in the Australian population of P. helianthi at some time. A primary aim of the work described was to apply our knowledge of pathotype evolution to improve resistance in sunflower to sunflower rust. Molecular markers were identified for a number of previously uncharacterised sunflower rust R-genes. These markers have been used to detect resistance genes in breeding lines and wild sunflower germplasm. A number of virulence loci that do not recombine were identified in P. helianthi. The resistance gene combinations corresponding to these virulence loci are currently being introgressed with breeding lines to generate hybrids with durable resistance to sunflower rust.

Item Type:Article
Corporate Creators:Department of Employment, Economic Development and Innovation (DEEDI), Agri-Science, Crop and Food Science, Plant Science
Business groups:Agri-Science, Crop and Food Science
Additional Information:© Australasian Plant Pathology Society. © CSIRO Publishing.
Keywords:Gene pyramiding; Helianthus annuus.
Subjects:Science > Botany > Cryptogams
Plant culture > Flowers and flower culture. Ornamental plants
Plant pests and diseases > Individual or types of plants or trees
Science > Biology > Genetics
Plant pests and diseases > Plant pathology
Deposited On:12 Jan 2009 06:20
Last Modified:26 Oct 2011 01:24

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