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Title: Effect of plant sterols and tannins on Phytophthora ramorum growth and sporulation

Author
item Stong, Rachel
item KOLODNY, ELI - Former ARS Employee
item KELSEY, RICK - Us Forest Service (FS)
item GONZÁLEZ-HERNÁNDEZ, M - University Of Santiago De Compostela
item Manter, Daniel

Submitted to: Journal of Chemical Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/28/2013
Publication Date: 5/21/2013
Citation: Stong, R.A., Kolodny, E., Kelsey, R., González-Hernández, M.P., Manter, D.K. 2013. Effect of plant sterols and tannins on Phytophthora ramorum growth and sporulation. Journal of Chemical Ecology. 39:733-743.

Interpretive Summary: The acquisition of plant sterols, mediated via elicitins, is required for growth and sporulation of Phytophthora spp. In this paper, we looked at the interaction between elicitins, sterols, and tannins. When ground leaf tissue was added to growth media, P. ramorum growth and sporulation was greatest on California bay laurel (Umbellularia californica) as compared to either California black oak (Quercus kelloggii) or Oregon white oak (Q. garryana). High levels of foliage resulted in an inhibition of P. ramorum growth and sporulation, particularly for the oak species. Inhibition of P. ramorum growth and sporulation was observed in response to either phytosterols or plant tannins; both were associated with a decline in the amount of P. ramorum elicitin but due to differing mechanisms. For example, high levels of sterols caused a decline in elicitin gene expression; whereas, tannins caused a decline in the amount of ‘functional’ or ELISA-detectable elicitin, but not gene expression. Across all treatment combinations, the level of P. ramorum growth and sporulation was strongly correlated with elicitin contents, suggesting a possible role for elicitin-sterol-tannin complexes to influence P. ramorum growth and sporulation in foliage.

Technical Abstract: The acquisition of plant sterols, mediated via elicitins, is required for growth and sporulation of Phytophthora spp. In this paper, we looked at the interaction between elicitins, sterols, and tannins. When ground leaf tissue was added to growth media, P. ramorum growth and sporulation was greatest on California bay laurel (Umbellularia californica) as compared to either California black oak (Quercus kelloggii) or Oregon white oak (Q. garryana). High levels of foliage resulted in an inhibition of P. ramorum growth and sporulation, particularly for the oak species. Inhibition of P. ramorum growth and sporulation was observed in response to either phytosterols or plant tannins; both were associated with a decline in the amount of P. ramorum elicitin but due to differing mechanisms. For example, high levels of sterols caused a decline in elicitin gene expression; whereas, tannins caused a decline in the amount of ‘functional’ or ELISA-detectable elicitin, but not gene expression. Across all treatment combinations, the level of P. ramorum growth and sporulation was strongly correlated with elicitin contents, suggesting a possible role for elicitin-sterol-tannin complexes to influence P. ramorum growth and sporulation in foliage.