White Pine Blister Rust in California: Ecology and Conservation Patricia Maloney 1, Detlev Vogler 2, Annette Delfino Mix 2 1 University of California Davis, Department of Plant Pathology & Tahoe Environmental Research Center 2 USDA Forest Service, Pacific Southwest Research Station & Institute of Forest Genetics
9 white pine species (Pinus subgenus Strobus) in North America - 6 in California Pinus albicaulis - whitebark pine Pinus balfouriana - foxtail pine Pinus flexilis - limber pine Pinus lambertiana - sugar pine Pinus longaeva - Great Basin bristlecone pine Pinus aristata - Rocky Mtn bristlecone pine Pinus ayacahuite - Mexican white pine Pinus strobiformis - Southwestern white pine Pinus strobus - Eastern white pine Pinus monticola - Western white pine
Photo: Martin Frye
Hydrologic functions & Watershed protection Biological Diversity & Wildlife habitat Photo: Deems Burton Carbon sequestration Important food resource
Threats to White Pine Species Non-native pathogen - Cronartium ribicola Climate change Climate-driven outbreaks of native insects Logging and habitat degradation Fire suppression & stand densification Catastrophic wildfires Photo: Deby Carter
Interactions between threats white pine blister rust fire suppression historical logging
Negative consequences white pine blister rust cone production wildlife
Pathogen introduction Two separate introductions of Cronartium ribicola (WPBR) into North America When:1890-1914 Where: Vancouver, BC & Geneva, NY How: Infected Eastern white pine seedlings shipped from France and Germany Heteroecious rust
Current distribution of Cronartium ribicola in western North America Timeline of spread into California ~ 1930 ~1937 ~1938 ~1944 ~1961 Map courtesy of D. Vogler and B. Geils
Disease resistance CR1 first discovered in sugar pine in 1970 (Kinloch, B.B., Jr., G.K. Parks, and C.W. Fowler. 1970. White pine blister rust: simply inherited resistance in sugar pine. Science 167: 193-195) Confers a hypersensitive response or HR Resistant response Susceptible response CR2 found in western white pine (Kinloch et al. 1999) Still today, these genes are the foundation for resistance to WPBR in California Additionally in both sugar and western white pine there are also complex traits (polygenic) that provide partial resistance (PR) - aka slow rusting resistance (SRR) Photo: Detlev Vogler Pitchy lesions PR/SRR Hypersensitive reaction in needles also found in limber pine and southwestern white pine Non-specific or systemic host reactions aka stem reaction are found in Great Basin bristlecone pine and Rocky Mountain bristlecone pine (D. Vogler and A. Delfino Mix, manuscript in preparation) To date no HR or systemic host reaction are found in whitebark pine or foxtail pine Photo: Detlev Vogler Photo: Detlev Vogler
Important Conservation Activities Gene conservation is a fundamental conservation activity to preserve genetic resources and biodiversity Invaluable resource for restoration and reforestation Starting point for many other conservation activities (e.g. disease resistance screening & evaluations, genetic/genomic studies, common garden studies & progeny tests) Seed resources in California: USDA Forest Service Region 5 Seed-bank USDA Forest Service, Pacific Southwest Research Station, Institute of Forest Genetics USDA ARS National Center for Genetic Resources Program http://www.ars.usda.gov/main/site_main.htm?modecode=54-02-05-00
Camille Jensen Tom Burt Martin Frye USDA FS R5 Sugar Pine Resistance Program USDA FS R5 Genetics Program Thank you Funding Sources: Southern Nevada Public Lands Management Act Nevada Division of State Lands-Lake Tahoe License Plate Program USDA Forest Service, Region 5 USDA Forest Service, Forest Health Monitoring
Lake Tahoe from Maggies Peaks Thomas Killion, 2005
Resistance/tolerance to Cronartium ribicola within three 5-needle pines: A case study from the Lake Tahoe Basin D. R. Vogler, A. Delfino Mix, P. E. Maloney USDA, FS, PSW IFG, and UC-Davis
SNPLMA white pine plots Boundaries of the LTBMU, showing distributions of demographic plots established for each of the white pine species endemic to the Tahoe Basin (2007-2015).
Modes of resistance
Hypersensitive reaction (HR) in needles Sugar pine (Pinus lambertiana), western white pine (Pinus monticola), southwestern white pine (Pinus strobiformis), and limber pine (Pinus flexilis)
Susceptible & resistant phenotypes in sugar (above) & western white pines Institute of Forest Genetics, Placerville, CA
Pollen receptor frequency Pollen receptor frequency Pollen R and white pine blister rust Sugar pine Western white pine 16 14 y = -0.1705x + 10.465 R² = 0.4713 14 12 y = -0.1395x + 5.1759 R² = 0.3247 12 10 10 8 6 4 8 6 4 2 2 0 0 10 20 30 40 50 60 % WPBR 0 0 10 20 30 40 50 % WPBR
Whitebark pine Needles readily infected No evidence of needle spot resistance; hence seedlings succumb to infection quickly Stem resistance, when present, requires several years to express, and occurs at low frequencies
Inoculated whitebark pine, Pinus albicaulis, Family 67 Institute of Forest Genetics, Placerville, CA
Inoculated whitebark pine, Pinus albicaulis, Family 96 Institute of Forest Genetics, Placerville, CA
Results Infection was greatest in whitebark pine plots (42% of trees) Survival (resistance?) was low (4%) in greenhouse inoculations Infection was intermediate in sugar pine plots (17%) 12% of families were heterozygous resistant (i.e., 50% of offspring exhibited needle-spot, or complete, resistance to inoculation), and 59% of families were pollen receptors (i.e., at least one seedling received a resistance allele from the pollen cloud) Infection was least in western white pine plots (11% of trees) 2% of families were heterozygous resistant, and 21% of families were pollen receptors
Infection on Ribes roezli: Blackwood Canyon, August 2015 Infection at a xeric site Infection at a mesic site
Acknowledgements In addition to their masterful roles as planners and authors, and as close and special friends: Patricia Maloney, for carrying out this research in the field and for being the primary initiator and author; also, for her photos of rust infection on Ribes roezli in the Tahoe Basin in August 2015. Annette Mix, for her ability to propagate, infect, and incubate white pine seedlings so that they reveal their most effective yet subtle responses to infection by Cronartium ribicola.
Rust-inoculated high-elevation white pines Institute of Forest Genetics, Placerville, CA November 2009