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Pacific Southwest Research Station
800 Buchanan Street
Albany, CA 94710-0011
About this research
Science Topics: Forest Genetics
Forest Genetics Topics:
Forest Disease Resistance, and Pathogen Evolution & Biogeography
The Institute of Forest Genetics disease resistance program is devoted to understanding genetic interactions between tree hosts and fungal pathogens, using both native and exotic pathogens as models for study. The disease resistance program is directed by Bro Kinloch, who works in collaboration with Det Vogler. Dr. Vogler also studies the evolution, systematics, biogeography, and landscape-level interactions of native and exotic pathogens (primarily rust fungi) with their plant hosts. In the same rust pathosystem, these can involve phylogenetically disparate hosts (e.g., white pine species and gooseberries or currants). The resistance program works in close collaboration with Region 5 and Region 6 Genetic Resources program.
The white pine/blister rust pathosystem
A disease native to Asia, white pine blister rust was introduced separately into both eastern and western North America early in the 20th century. In both cases, the vector was seedlings of native eastern white pine imported from European nurseries, where they had become infected. Blister rust had first appeared in Europe in the mid-nineteenth century, and within three decades had spread across the continent wherever the popular eastern white pine had been planted. The life cyle of blister rust includes an alternate host.
In western North America, the rust spread in serial jumps from a nursery near Vancouver, British Columbia, south through the Cascades and Sierra Nevada, and east to the northern Rocky Mountains. All native white pine are susceptible to damage. Economic impact has been most acute on the two large commercial species, western white pine and sugar pine, but ecological damage has been equally severe on high elevation species such as whitebark and limber pines in many places. More recently, an outbreak was recorded in the Sacramento Mountains of New Mexico on southwestern white pine. Infection is not always uniform; it often forms a mosaic pattern over the landscape, where patches of intense infection give way to areas of lighter or no infection.
Mechanisms and inheritance of resistance
Deployment strategies for durable resistance
Evolution and biogeography of fungal pathogens within forested ecosystems
Biogeographic studies on pine stem rust fungi and their hosts
This research involves extensive field data and sample collection documenting distribution of pine stem rust fungi in the western U.S. on both pine and angiosperm hosts, with particular emphasis on white pine blister rust, pinyon blister rust, and western gall rust. Collections incorporate host and fungal tissue for DNA and biogeographic analyses of all partners in the pathosystems. One goal of these studies is to compare the range extension and host interactions of introduced exotic (white pine blister rust) and endemic (pinyon blister rust and western gall rust) pathogens.
Potential for cryptic speciation in heteroecious, autoecious, and facultatively autoecious pine stem rust fungi
Sample collection, geographic location, and genetic analysis of spore color-mutant autoecious gall rust fungi (infect pines only) around the periphery of the Great Basin where they form small, relict, genetically-isolated populations. In many cases, these organisms exist in isolated locations under constraints to range extension that remain unknown. As with more well-documented pine stem rusts, like the western gall rust fungus, these pathogens exhibit the ability to expand their geographic and host ranges rapidly, acting biologically like invasive exotics. Studies of these fungi hold promise for understanding the modes and trajectories of pathogens within rapidly-changing or threatened forested ecosystems.
Diversity within pine stem rust fungi of Mexico and Central America
Because both pine hosts and pine-infecting stem rust fungi extend as far southward as the Gulf Coast of Nicaragua, diversity and speciation within these organisms, as compared to their nearest relatives in the U.S. and Canada, is an important key to understanding of Cronartium and Peridermium species evolutionary history and pathogenic potential. Recent trips to Mexico and Central America have documented rusts similar to but possibly phylogenetically-divergent from North American taxa. DNA sequence analyses currently underway will be used to better understand speciation and diversity within these species.
|Last Modified: Aug 29, 2016 11:00:23 AM|