Canadian Forest Service Publications
Confirmation of dominant gene resistance (Cr2) in US white pine selections to white pine blister rust growing in British Columbia. 2004. Hunt, R.S.; Jensen, G.D.; Ekramoddoullah, A.K.M. Pages 227-229 in R. Sniezko, S. Samman, S.E. Schlarbaum, and H. Kriebel, editors. Breeding and genetic resources of five-needle pines: growth, adaptability, and pest resistance, Proceedings: of the IUFRO Five-Needle Pines Working Party Conference. July 23-27, 2001, Medford, OR. USDA Forest Service, Rocky Mountain Research Station, Fort Collins, CO, RMRS-P-32.
Issued by: Pacific Forestry Centre
Catalog ID: 32474
Availability: PDF (download)
To demonstrate the existence of the dominant Cr2 blister rust resistance gene in Dorena derived stock already producing seed in British Columbia, about 50 seedlings/parent tree were inoculated and examined for hypersensitive needle spots. Seedlings from 33 of 42 canker-free parents produced hypersensitive spots, confirming the presence of Cr2 in the parent trees. To determine if an existing pathotype might have already overcome the Cr2 gene in British Columbia, seedlings from three suspect trees (because they were canker-free for 10 years, but recently became cankered) were inoculated. The Cr2 gene was absent in these three trees. Additionally, seedlings from two seedlots known to possess the Cr2 gene were subjected to two consecutive annual inoculations. This double inoculation was repeated on five different occasions with a composite inoculum. Canker-free seedlings following the first inoculation remained canker-free after a second inoculation, consistent with the uncompromised expression of Cr2.