Influence of Host Resistance on the Genetic Structure of the White Pine Blister Rust Fungus in the Western United States

• Published in: Phytopathology Vol. 98; no. 4; pp. 413 - 420
• Main Authors: Richardson, B.A, Klopfenstein, N.B, Zambino, P.J, McDonald, G.I, Geils, B.W, Carris, L.M
• Format: Journal Article
• Language: English
• Published: St. Paul, MN American Phytopathological Society 01.04.2008
• Subjects: Biological and medical sciences; Cronartium ribicola; disease resistance; Disease Susceptibility; environmental factors; evolution; forest trees; Fundamental and applied biological sciences. Psychology; Fungal plant pathogens; Fungi - genetics; Fungi - physiology; genetic polymorphism; genetic resistance; genetic variation; geographical variation; heterozygosity; host plants; loci; major genes; montane forests; natural selection; Phylogeny; Phytopathology. Animal pests. Plant and forest protection; Pinaceae - microbiology; Pinus lambertiana; Pinus monticola; Plant Diseases - microbiology; population genetics; rust diseases; tree diseases; United States; Oregon; California; Colorado; Idaho; United States; North America; America; Gene cluster; Plant pathology; Microbiology; Plant pathogen; Virulence; Genetic diversity; Population genetics; Pinus lambertiana; Basidiomycota; Fungi; Cronartium ribicola; Resistance; Gene; Softwood forest tree; Gymnospermae; Environment; Isolate; Pinus monticola; Coniferales; Spermatophyta; Amplified fragment length polymorphism marker
• ISSN: 0031-949X; 1943-7684
• DOI: 10.1094/PHYTO-98-4-0413

Cronartium ribicola, the causal agent of white pine blister rust, has been devastating to five-needled white pines in North America since its introduction nearly a century ago. However, dynamic and complex interactions occur among C. ribicola, five-needled white pines, and the environment. To examine potential evolutionary influences on genetic structure and diversity of C. ribicola in western United States, population genetic analyses of C. ribicola were conducted using amplified fragment length polymorphism (AFLP) molecular markers. The fungus was sampled at six sites. Collections for two of the six sites were from separate plantings of resistant-selected western white pine and sugar pine. Heterozygosity based on polymorphic loci among populations ranged from 0.28 to 0.40, with resistant-selected plantations at the extremes. Genetic differentiation was also highest between these two populations. Principal coordinates analysis and Bayesian assignment placed most isolates that are putative carriers of virulence to major-gene resistance into a discernable cluster, while other isolates showed no clustering by site or host species. These results indicate that C. ribicola in western North America is not genetically uniform, despite its presumed single site of introduction and relatively brief residence. Moreover, major-gene resistance appears to have imposed strong selection on the rust, resulting in reduced genetic diversity. In contrast, no evidence of selection was observed in C. ribicola from hosts that exhibit only multigenic resistance.