Comparative mapping of five-needle pine major genes for resistance to white pine blister rust
J. LIU (1), R. Sniezko (2) (1) 506 West Burnside Road, Canada; (2) USDA Forest Service, Dorena Genetic Resource Center, U.S.A.

Susceptibility of native five-needle pines to white pine blister rust (WPBR), caused by the exotic fungus Cronartium ribicola, has resulted in reduction of wild populations in North America. Development of marker-assisted selection (MAS) tools will enhance tree breeding and restoration of disturbed forest ecosystems. Major resistance (R) genes against specific C. ribicola avirulent isolates have been found in four pine species. In this study we screened genic SNP markers by comparative transcriptome analysis and association genetic study, constructed saturated linkage maps for western white pine R gene (Cr2), performed comparative mapping among Pinus species, and developed MAS tools for breeding program. The phenotypic segregation was determined by hypersensitive reaction (HR)-like response on the needle and disease symptom of cankered stems post inoculation by avcr2 race. HRM and TaqMan arrays were used for SNP genotyping for Cr2 linkage analysis. A saturated Cr2-map was constructed by integrating maps of three seed families with a total of 32 SNP markers from 21 genes. The Cr2 gene was mapped to the Pinus consensus linkage group1 (LG1) as compared to other Pinus species. Previous works mapped limper pine Cr4 and sugar pine Cr1 on the LG8 and LG2 respectively, indicating that R genes against C. ribicola have evolved independently in different species. Our results provide valuable molecular markers and genetic information for developing WPBR-resistant seed orchard in diverse germplasm and for distinguishing Cr2 from other known or novel R genes in five-needle pine breeding.

Abstract Number: P12-398
Session Type: Poster