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. 2021 Sep 8;368(17):fnab113.
doi: 10.1093/femsle/fnab113.

The Fatty Acid Methyl Ester (FAME) profile of Phytophthora agathidicida and its potential use as diagnostic tool

Randy F Lacey  1   2 , Blake A Sullivan-Hill  1 , Julie R Deslippe  1   3 , Robert A Keyzers  2   4   3 , Monica L Gerth  1   2
Affiliations

The Fatty Acid Methyl Ester (FAME) profile of Phytophthora agathidicida and its potential use as diagnostic tool

Randy F Lacey et al. FEMS Microbiol Lett. .

Abstract

Phytophthora diseases cause devastation to crops and native ecosystems worldwide. In New Zealand, Phytophthora agathidicida is threatening the survival of kauri, an endemic, culturally and ecologically important tree species. The current method for detecting P. agathidicida is a soil bating assay that is time-consuming and requires high levels of expertise to assess, thus limiting the analytical sample throughput. Here, we characterized the fatty acid methyl ester (FAME) profile of P. agathidicida. We also compared it with the FAME profile of P. cinnamomi and assessed the efficacy of FAME analysis as a diagnostic tool for detecting the pathogen in soil samples. In FAME analysis, the total fatty acid content is isolated from a sample and converted to FAMEs for analysis, a process that takes less than a day. Unique fatty acid acyl chains can serve as biomarkers for specific organisms. We detected 12 fatty acids in P. agathidicida, two of which (20:4ω6 and 20:5ω3) show promise as potential Phytophthora specific biomarkers. Collectively, these findings advance our fundamental understanding of P. agathidicida biology and provide a promising technique to increase the rate of sample processing and the speed of pathogen detection for P. agathidicida in soil.

Keywords: Phytophthora; Phytophthora agathidicida; diagnostics; fatty acid methyl ester analysis.

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Figures

Figure 1.
Figure 1.
Fatty acid profile of P. agathidicida and P. cinnamomi at varying temperatures. FAMEs were produced and analysed from mycelia of P. agathidicida(A) and P. cinnamomi(B) grown at 16 and 22°C. The % of each fatty acid is the average relative % of five biological replicates. Error bars indicate standard deviation.
Figure 2.
Figure 2.
Fatty acid profile comparison of different P. agathidicida lifecycle stages. FAMEs were produced and analysed from P. agathidicida mycelia, oospores and zoospores. The % of each fatty acid is an average relative % of five biological replicates. Error bars indicate standard deviation.
Figure 3.
Figure 3.
Quantification of 20:4ω6 and 20:5ω3 fatty acids in soil samples with P. agathidicida oospores added. Oospores were added at varying concentrations to 0.5 g of soil containing a 19:0 fatty acid internal standard. FAMEs were then produced and analysed from each sample, and the concentration of 20:4ω6 and 20:5ω3 was determined as nmol/g of soil. The values are an average of five biological replicates. Error bars indicate standard deviation.
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References

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