Metabolomic Analysis of Phytophthora parasitica Growth in the Presence of β-sitosterol Indicates Adaptive Mechanisms Modulated by Sterols.

Phytophthora parasitica is a generalist phytopathogenic oomycete that infects a series of crops with great economic interest, including tomato, tobacco, and citrus species. Sterols are essential lipids in eukaryotic organisms, playing a fundamental role in the structure and function of the cell membrane. Oomycete from Peronosporales order, including Phytophthora spp., are known for their inability to synthesize sterols, a characteristic that distinguishes them from many other organisms and influences their biology and pathogenicity. This dependence is not only crucial for zoospore sporulation but also for vegetative growth. Following the scenario at which sterol auxotrophy can interfere in the metabolism of such important phytopathogen, in this study we investigate whether β-sitosterol modulates the metabolome of P. parasitica and its vegetative growth. For that, we used liquid chromatography-mass spectrometry LC-HRMS combined with chemometric tools, to assess the metabolite profile of P. parasitica under different concentrations of β-sitosterol in the culture media. Even though mycelial growth was not significantly affected by different sterol concentrations, an evident metabolic reprogramming of the oomycete was detected. Among the metabolites differentially produced in the sterol presence are the sphingolipid sphinganine, histidine and the nucleoside methylthioadenosine. We discuss the influence of these metabolites in vegetative growth of the oomycete and infer possible roles in environmental adaptation and pathogenicity.