Effect of Plant Sterols and Tannins on Phytophthora ramorum Growth and Sporulation

• DOI: 10.1007/s10886-013-0295-y
• Publication Date: 2013-05-20T05:27:54Z
• Authors: Rachel A. Stong; Eli Kolodny; Rick G. Kelsey; M. P. González-He...; Jorge M. Vivanco; Daniel K. Manter
• Keywords: Phytophthora ramorum

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).