title: Is variation in susceptibility to Phytophthora ramorum correlated with population genetic structure in coast live oak (Quercus agrifolia)?
abstract: California coastal woodlands are suffering severe disease and mortality as a result of infection from Phytophthora ramorum. Quercus agrifolia is one of the major woodland species at risk. This study investigated within- and among-population variation in host susceptibility to inoculation with P. ramorum and compared this with population genetic structure using molecular markers. Susceptibility was assessed using a branch-cutting inoculation test. Trees were selected from seven natural populations in California. Amplified fragment length polymorphism molecular markers were analysed for all trees used in the trials. Lesion sizes varied quantitatively among individuals within populations, with up to an eightfold difference. There was little support for population differences in susceptibility. Molecular structure also showed a strong within-population, and weaker among-population, pattern of variation. Our data suggest that susceptibility of Q. agrifolia to P. ramorum is variable and is under the control of several gene loci. This variation exists within populations, so that less susceptible local genotypes may provide the gene pool for regeneration of woodlands where mortality is high.
authors.affiliation: Department of Environmental Science Policy and Management, 151 Hilgard Hall, University of California, Berkeley, CA 94720, USA. dodd@nature.berkeley.edu
authors.forename: Richard S
authors.initials: RS
authors.lastname: Dodd
authors.forename: Daniel
authors.initials: D
authors.lastname: Hüberli
authors.forename: Vlad
authors.initials: V
authors.lastname: Douhovnikoff
authors.forename: Tamar Y
authors.initials: TY
authors.lastname: Harnik
authors.forename: Zara
authors.initials: Z
authors.lastname: Afzal-Rafii
authors.forename: Matteo
authors.initials: M
authors.lastname: Garbelotto
mesh_terms: D002140:California; D005819:Genetic Markers; D020022:Genetic Predisposition to Disease; D014644:Genetic Variation; D010802:Phylogeny; D010838:Phytophthora / Q000502:physiology*; D010935:Plant Diseases / Q000235:genetics* / Q000469:parasitology*; D011110:Polymorphism, Genetic; D029963:Quercus / Q000235:genetics* / Q000469:parasitology*; D012621:Seasons
chemical_list: D005819:Genetic Markers