Role of Basidiomycete fungi in the grapevine trunk disease Esca

Authors: BROWN, ALBRE - California Department Of Food And Agriculture; LAWRENCE, DANIEL - University Of California, Davis; Baumgartner, Kendra

Submitted to: Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/23/2019
Publication Date: 11/27/2019
Citation: Brown, A.A., Lawrence, D.P., Baumgartner, K. 2019. Role of Basidiomycete fungi in the grapevine trunk disease Esca. Plant Pathology. 69(2):205-220. https://doi.org/10.1111/ppa.13116.
DOI: https://doi.org/10.1111/ppa.13116

Interpretive Summary: Esca is thought to be caused by multiple fungi, combinations of which may be more damaging to the vine in terms of certain symptoms becoming more severe. Knowing which combinations lead to the most severe symptoms may help grape growers and nurseries rank their trunk-disease management efforts. Phaeomoniella chlamydospora and various wood-rotting basidiomycete fungi, namely Fomitiporia spp., are known Esca pathogens. However, the effect of the sequence of pathogen infection on disease development is unclear. To determine the impact of single and dual inoculations on symptoms, potted table grape ‘Crimson Seedless’ was inoculated with P. chlamydospora either alone or in combination with one of four basidiomycetes: Coprinellus radians, Fomitiporia langloisii, F. polymorpha, and new species Tropicoporus texanus (described here). Basidiomycetes were isolated from vines with foliar symptoms of Esca in California and Texas. In dual inoculations, the effects of different sequences of infection (P. chlamydospora first, basidiomycete 6 months later; and vice versa) were tested, compared to simultaneous co-inoculations, into two wounds per stem. Plants inoculated with P. chlamydospora either alone or in combination, in any sequence, with a basidiomycete did not differ significantly in the length of black-streaking lesions. In plants inoculated only with a basidiomycete, our findings of large white-rot lesions and absence of this wood symptom from control plants suggest that C. radians, F. langloisii, and T. texanus are pathogenic. Foliar symptoms resembling those of Esca in the field (marginal and interveinal schorching and red or yellow discoloration) were more frequent among plants inoculated F. polymorpha or T. texanus, simultaneously or following P. chlamydospora. Sequential inoculations of a basidiomycete before or after P. chlamydospora were associated with similar lesion lengths, suggesting that basidiomycetes may not require infection by P. chlamydospora in order to extensively colonize the wood.

Technical Abstract: Phaeomoniella chlamydospora and various wood-rotting basidiomycete fungi, namely Fomitiporia spp., are known Esca pathogens. However, the effect of the sequence of pathogen infection on disease development is unclear. To determine the impact of single and dual inoculations on symptoms, potted Vitis vinifera ‘Crimson Seedless’ was inoculated with P. chlamydospora either alone or in combination with one of four basidiomycetes: Coprinellus radians, Fomitiporia langloisii, F. polymorpha, and novel species Tropicoporus texanus. Basidiomycetes were isolated from vines with foliar symptoms of Esca in California and Texas. In dual inoculations, the effects of different sequences of infection (P. chlamydospora first, basidiomycete 6 months later; and vice versa) were tested, compared to simultaneous co-inoculations, into two wounds per stem. Plants inoculated with P. chlamydospora either alone or in combination, in any sequence, with a basidiomycete did not differ significantly in the length of black-streaking lesions. In plants inoculated only with a basidiomycete, our findings of large white-rot lesions and absence of this wood symptom from control plants suggest that C. radians, F. langloisii, and T. texanus are pathogenic. Foliar symptoms resembling those of Esca in the field (marginal and interveinal schorching and red or yellow discoloration) were more frequent among plants inoculated F. polymorpha or T. texanus, simultaneously or following P. chlamydospora. Sequential inoculations of a basidiomycete before or after P. chlamydospora were associated with similar lesion lengths, suggesting that basidiomycetes may not require infection by P. chlamydospora in order to extensively colonize the wood.