title: A curious case of resistance to a new encounter pathogen: myrtle rust in Australia.
abstract: Resistance genes (R genes) in plants mediate a highly specific response to microbial pathogens, often culminating in localized cell death. Such resistance is generally pathogen race specific and believed to be the result of evolutionary selection pressure. Where a host and pathogen do not share an evolutionary history, specific resistance is expected to be absent or rare. Puccinia psidii, the causal agent of myrtle rust, was recently introduced to Australia, a continent rich in myrtaceous taxa. Responses within species to this new pathogen range from full susceptibility to resistance. Using the myrtle rust case study, we examine models to account for the presence of resistance to new encounter pathogens, such as the retention of ancient R genes through prolonged 'trench warfare', pairing of resistance gene products and the guarding of host integrity.
authors.affiliation: Department of Plant and Food Sciences, Faculty of Agriculture and Environment, University of Sydney, Eveleigh, NSW, 2015, Australia.
authors.forename: Peri A
authors.initials: PA
authors.lastname: Tobias
authors.affiliation: Department of Plant and Food Sciences, Faculty of Agriculture and Environment, University of Sydney, Eveleigh, NSW, 2015, Australia.
authors.forename: David I
authors.initials: DI
authors.lastname: Guest
authors.affiliation: Research School of Biology, Australian National University, Canberra, ACT, 2601, Australia.
authors.forename: Carsten
authors.initials: C
authors.lastname: Külheim
authors.affiliation: Research School of Biology, Australian National University, Canberra, ACT, 2601, Australia.
authors.forename: Ji-Fan
authors.initials: JF
authors.lastname: Hsieh
authors.affiliation: Department of Plant and Food Sciences, Faculty of Agriculture and Environment, University of Sydney, Plant Breeding Institute, Narellan, NSW, 2567, Australia.
authors.forename: Robert F
authors.initials: RF
authors.lastname: Park
mesh_terms: D001315:Australia; D001487:Basidiomycota / Q000502:physiology*; D060467:Disease Resistance / Q000235:genetics*; D017343:Genes, Plant; D054884:Host-Pathogen Interactions; D031651:Myrtus / Q000235:genetics* / Q000382:microbiology*; D010935:Plant Diseases / Q000382:microbiology*
keywords: Puccinia psidii; R gene; myrtle rust; new encounter pathogen