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Virulence gene distribution and dynamics of the white pine blister rust pathogen in western North America
- We assayed the distribution and frequency of two genes of the blister rust pathogen with specific virulence to major resistance genes in sugar pine and western white pine in inoculum from extensive parts of the hosts' ranges. The genes, vcr1 and vcr2, differentially neutralize the cognate resistance alleles Cr1 and Cr2 of the two respective hosts and are clearly marked by their interaction phenotypes. Basidiospores from each inoculum source were cast over Cr1 and Cr2 host genotypes simultaneously, and interaction phenotypes scored when developed. vcr1 was confined to sites with high concentrations of Cr1 (mostly plantations) where frequencies tended toward fixation. vcr2 showed a similar tendency, except high frequencies were occasionally observed from natural and planted stands of western white pine with very low frequencies of Cr2. Otherwise, no pattern was evident for either allele: frequencies were very erratic from site to site within short distances (<1 to 7 km) of each other and oscillated with high amplitudes at the same sites measured in consecutive years. Intense selection for virulence by Cr alleles occurs locally, but spread of vcr alleles over the landscape is mitigated by remarkably low gene flow. Absence of heterozygotes among single telia inoculum on Cr2 genotypes indicated cytoplasmic inheritance of vcr2, similar to vcr1 (previously reported).
Kinloch, B.B. Jr. , Sniezko, R.A. , Dupper, G.E.
Pinus lambertiana , Pinus monticola , forest trees , rust diseases , Cronartium ribicola , plant pathogenic fungi , pathogenicity , virulence , inheritance (genetics) , genes , disease resistance , alleles , gene frequency , disease prevalence , geographical distribution , California , Oregon , Washington , Idaho
- Includes references
- Phytopathology 2004 July, v. 94, no. 7
Journal Articles, USDA Authors, Peer-Reviewed
- Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.