A comparison of the metabolomic response of grapevine to infection with Ascomycete wood-infecting fungi

Authors: GALARNEAU, ERIN - University Of California, Davis; LAWRENCE, DANIEL - University Of California, Davis; Wallis, Christopher; Baumgartner, Kendra

Submitted to: Physiological and Molecular Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/24/2020
Publication Date: 1/18/2021
Citation: Galarneau, E.R., Lawrence, D.P., Wallis, C.M., Baumgartner, K. 2021. A comparison of the metabolomic response of grapevine to infection with Ascomycete wood-infecting fungi. Physiological and Molecular Plant Pathology. 113. Article 101596. https://doi.org/10.1016/j.pmpp.2020.101596.
DOI: https://doi.org/10.1016/j.pmpp.2020.101596

Interpretive Summary: Grapevine trunk diseases (Botryosphaeria dieback, Eutypa dieback, Esca) attack the permanent, woody structure of the vine, with internal lesions developing in wood colonized by the fungal pathogens. These visibly darkened areas of the infected wood develop at different rates, depending in part on how aggressive the pathogens attack. The plant responds to the infection in a number of ways, including undergoing biochemical changes that may affect the rate at which the pathogen colonizes the wood. We characterized this metabolic response in the woody stem of potted plants of Vitis vinifera ‘Cabernet Sauvignon’, inoculated with common fungal pathogens in California: Eutypa lata (Eutypa dieback), Phaeomoniella chlamydospora (Esca), and Diplodia seriata and Neofusicoccum parvum (Botryosphaeria dieback). Wounded and non-wounded plants served as controls. Amino acids, free sugars, phenolics, and terpenoids were measured around wood lesions at 0, 0.5, 2, and 3 months post-inoculation (MPI). The largest lesions were associated with P. chlamydospora, especially at 3 MPI. Among plants inoculated with the four fungi, there were differences in amino acid and phenolic concentrations at 2 MPI, and differences in sugars and terpenoids at 0.5 MPI. Amino acids accumulated with D. seriata infection, whereas sugars decreased with D. seriata and P. chlamydospora infection. Different flavonoid phenolics were induced depending on the pathogen, and stilbene phenolics were at the highest levels with P. chlamydospora infection. Terpenoids decreased with infection, especially with P. chlamydospora. Similarities and differences in the metabolic host defense among plants inoculated with the different pathogens may reflect differential fungal virulence, in terms of lesion development, and/or different mechanisms of colonization, such as toxin production and enzymatic degradation of cell-wall carbohydrates.

Technical Abstract: Grapevine trunk diseases attack the permanent, woody structure of the vine, with internal lesions developing in wood colonized by the causal fungi. Lesions develop at different rates, depending in part on fungal virulence, and thus may be associated with different metabolic host defenses. Potted plants of Vitis vinifera ‘Cabernet Sauvignon’ were inoculated with common fungal pathogens in California: Eutypa lata (Eutypa dieback), Phaeomoniella chlamydospora (Esca), and Diplodia seriata and Neofusicoccum parvum (Botryosphaeria dieback). Wounded and non-wounded plants served as controls. Amino acids, free sugars, phenolics, and terpenoids were measured around wood lesions at 0, 0.5, 2, and 3 months post-inoculation (MPI), by gas chromatography (GC), high performance liquid chromatography (HPLC), or GS-Mass Spectrometry (GCMS). The largest lesions were associated with P. chlamydospora, especially at 3 MPI. Among plants inoculated with the four fungi, there were differences in amino acid and phenolic concentrations at 2 MPI, and differences in sugars and terpenoids at 0.5 MPI. Amino acids accumulated with D. seriata infection, whereas sugars decreased with D. seriata and P. chlamydospora infection. Different flavonoid phenolics were induced depending on the pathogen, and stilbene phenolics were at the highest levels with P. chlamydospora infection. Terpenoids decreased with infection, especially with P. chlamydospora. Similarities and differences in the metabolic host defense among plants inoculated with the different pathogens may reflect differential fungal virulence, in terms of lesion development, and/or different mechanisms of colonization, such as toxin production and enzymatic degradation of cell-wall carbohydrates.