title: Effect of plant sterols and tannins on Phytophthora ramorum growth and sporulation.
abstract: Elicitin-mediated acquisition of plant sterols is required for growth and sporulation of Phytophthora spp. This study examined the interactions between elicitins, sterols, and tannins. Ground leaf tissue, sterols, and tannin-enriched extracts were obtained from three different plant species (California bay laurel, California black oak, and Oregon white oak) in order to evaluate the effect of differing sterol/tannin contents on Phytophthora ramorum growth. For all three species, high levels of foliage inhibited P. ramorum growth and sporulation, with a steeper concentration dependence for the two oak samples. Phytophthora ramorum growth and sporulation were inhibited by either phytosterols or tannin-enriched extracts. High levels of sterols diminished elicitin gene expression in P. ramorum; whereas the tannin-enriched extract decreased the amount of 'functional' or ELISA-detectable elicitin, but not gene expression. Across all treatment combinations, P. ramorum growth and sporulation correlated strongly with the amount of ELISA-detectable elicitin (R (2) = 0.791 and 0.961, respectively).
authors.affiliation: USDA-ARS, Soil-Plant-Nutrient Research, Fort Collins, CO, USA.
authors.forename: Rachel A
authors.initials: RA
authors.lastname: Stong
authors.forename: Eli
authors.initials: E
authors.lastname: Kolodny
authors.forename: Rick G
authors.initials: RG
authors.lastname: Kelsey
authors.forename: M P
authors.initials: MP
authors.lastname: González-Hernández
authors.forename: Jorge M
authors.initials: JM
authors.lastname: Vivanco
authors.forename: Daniel K
authors.initials: DK
authors.lastname: Manter
mesh_terms: D005656:Fungal Proteins / Q000378:metabolism*; D010838:Phytophthora / Q000187:drug effects* / Q000254:growth & development / Q000502:physiology; D010840:Phytosterols / Q000494:pharmacology*; D018515:Plant Leaves / Q000737:chemistry; D011506:Proteins / Q000378:metabolism*; D029963:Quercus / Q000737:chemistry; D013045:Species Specificity; D013172:Spores, Fungal / Q000187:drug effects* / Q000502:physiology; D013634:Tannins / Q000494:pharmacology*; D027422:Umbellularia / Q000737:chemistry
chemical_list: D005656:Fungal Proteins; D010840:Phytosterols; D011506:Proteins; D013634:Tannins; C085101:elicitin, Phytophthora