PAG-XVI  Plant & Animal Genomes XVI Conference

January 12-16, 2008
Town & Country Convention Center
San Diego, CA


P512 : Forest Trees

Genetic Mapping Of Genes Controlling Slow-Rust Resistance And Major Gene Resistance In Sugar Pine

Kathleen D Jermstad1 , David B. Neale2

1  Institute of Forest Genetics, Pacific Southwest Research Station, 2480 Carson Road, Placerville, CA, 95667, USA
2  Department of Plant Sciences, University of California, 1 Shields Avenue, Davis, CA, 95619, USA

Pines belonging to the Pinus subgenus Strobus are susceptible to a fungal pathogen (Cronartium ribicola) that was introduced to Northern America in the early 1900s. Surprisingly, several white pines have been shown to possess innate resistance to the rust infection. Two forms of resistance have been observed: 1) polygenic resistance (also known as quantitative or partial resistance) which expresses a wide distribution in disease phenotypes, and 2) monogenic resistance (also known as major gene resistance – MGR) which segregates in progeny as a single dominant gene. Breeding programs for deployment of the MGR are currently in place for sugar pine (Pinus lambertiana) however, resistance controlled by a suite of genes is likely to be more durable. Using sugar pine as a representative species, we are employing several strategies to develop genomic resources for the five-needled pines. Single nucleotide polymorphisms (SNPs) identified in 1200 loblolly pine (P.taeda) EST sequences from will be used for nucleotide diversity studies and comparative genomics within the Pinaceae (http://www.nsf.gov/awardsearch/showAward.do?AwardNumber=0638502) including sugar pine. An EST resource is currently being developed for sugar pine through a grant recently awarded by the Joint Genome Initiative Community Sequencing Program (JGI-CSP_LOI_783956). Both of these EST resources will provide markers for genetic mapping in sugar pine. The mapping of quantitative trait loci (QTL) for partial resistance is underway in a large full-sib family (n~1000). In addition to mapping QTL for partial resistance, we are also pursuing a positional cloning strategy to isolate the DNA sequence (allele) conferring MGR. The DNA sequence for the allele conferring MGR in sugar pine would provide an important diagnostic tool for studying range-wide population substructure and managing forest health.