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ARS Home » Pacific West Area » Parlier, California » San Joaquin Valley Agricultural Sciences Center » Crop Diseases, Pests and Genetics Research » Research » Publications at this Location » Publication #415919
Research Project: Development of Applied Management Systems for Diseases of Perennial Crops with Emphasis on Vector-Borne Pathogens of Grapevine and Citrus

Location: Crop Diseases, Pests and Genetics Research

Title: Fatty acid methyl ester (FAME)profiling for species-specific characterization and detection of fungal pathogens that cause tree and grapevine truck diseases

Author
item Wallis, Christopher
item Baumgartner, Kendra

Submitted to: Mycologia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/5/2024
Publication Date: 1/22/2025
Citation: Wallis, C.M., Baumgartner, K. 2025. Fatty acid methyl ester (FAME)profiling for species-specific characterization and detection of fungal pathogens that cause tree and grapevine truck diseases. Mycologia. 117(2): 319-330. https://doi.org/10.1080/00275514.2024.2439753.
DOI: https://doi.org/10.1080/00275514.2024.2439753

Interpretive Summary: Fungal trunk pathogens are of increasing concern for orchard and vineyard managers worldwide due to reduced yields over time. Proper identification is required to initiate appropriate controls, but morphological identification is difficult and DNA-based approaches can be time-consuming. Therefore, a fatty acid methyl ester (FAME) profiling for multiple isolates of different fungal trunk pathogen species was developed. FAME profiling accurately identified isolates to species, and also revealed subgrouping within species. These results support application of FAME profiling as a novel for plant disease diagnostics.

Technical Abstract: Fungal trunk diseases, including bot canker, Eutypa dieback, and esca, are major concerns for tree fruit, nut, and grape growers throughout the world. Albeit the different fungal pathogens that cause trunk disease, including Diplodia mutila, Diplodia seriata, Eutypa lata, Neofusicoccum mediterraneum, Neofusicoccum parvum, Phaeomoniella chlamydospora and Phaeoacremonium minimum, might cause similar symptoms in the respective host plants, different species and strains vary in the severity of diseases that are caused. Therefore, identification and better systematics are needed to confirm the management levels necessary to provide appropriate control. Fatty acid methyl ester (FAME) profiling can be an effective way to characterize and identify fungal species and strains. Therefore, FAME analyses were conducted on multiple strains of fungal trunk disease pathogens to characterize profiles and assess whether this technique could separate distinct strains. FAME profiles were dominated by oleic acid (18:1 '9c) and palmitic acid (16:0), with less abundant fatty acids in different ratios for each species and strains within species. Canonical discriminant analyses revealed which minor fatty acids could be most informative at profile variance, with 20 different fatty acids that can explain 75.81% of profile variance in the first two canonicals. Using these, samples were self-tested and correctly sorted over 99% of the time. Within species, canonical discriminant analyses were able to separate stains further, often by original geographical location or by host plant species. These results further suggest potential novel species, subspecies or races may be present amongst the strains analysed, demonstrating the capacity of FAME to discover cryptospecies and accurately identify fungal pathogens.