Date Published: March 26, 2019
Publisher: Public Library of Science
Author(s): Giovanni Del Frari, Ana Cabral, Teresa Nascimento, Ricardo Boavida Ferreira, Helena Oliveira, Sabrina Sarrocco.
Epicoccum is a genus of ascomycetes often associated with the mycobiome of grapevines (Vitis vinifera). Epicoccum spp. are found in the soil, phyllosphere, as well as in the wood, where they interact both with the plant and with other endophytes and pathogens. Wood pathogens involved in the esca disease complex, a grapevine trunk disease, are particularly concerning in viticulture, as current control strategies have proven unsatisfactory. This study investigated the interaction among Epicoccum spp. and three esca-associated fungi, with the aim of establishing whether they are suitable candidates for biological control.A screening conducted in vitro, by means of dual culture, revealed that all tested Epicoccum spp. inhibited the growth of pathogens Phaeomoniella chlamydospora and Fomitiporia mediterranea, while only some of them inhibited Phaeoacremonium minimum. Epicoccum layuense E24, identified as the most efficient antagonist, was tested in rooted grapevine cuttings of cultivars Cabernet Sauvignon and Touriga Nacional, under greenhouse conditions, against P. chlamydospora and P. minimum. This study revealed that the inoculation of E. layuense E24 produced a successful colonization of the wood of grapevines; in addition it did not impair the growth of the plants or induce the appearance of symptoms in leaves or in wood. Moreover, grapevines colonized by E. layuense E24 showed a considerable decrease in the wood symptomatology caused by the inoculated pathogens (by 31–82%, depending on the pathogen/grapevine cultivar), as well as a reduction in their frequency of re-isolation (60–74%).Our findings suggest that E. layuense E24 is a promising candidate for its application in biological control, due to its antagonistic interaction with some esca-associated fungal pathogens.
Grapevine trunk diseases (GTDs) are an increasing threat to worldwide viticulture [1–3]. Affected grapevines (Vitis vinifera L.) exhibit lower vigor, reduced productivity and quality of yields, shorter lifespan; which, altogether, cause considerable economic losses [3,4]. The causal agents of these diseases are found in diverse groups of both ascomycetes and basidiomycetes, which can colonize the woody tissues of grapevines, interfering with the plant physiology, microbial ecology and activating plant response mechanisms [1,5]. Symptoms of an infection by trunk disease pathogens are often elusive. They are found primarily in the wood, in the form of brown streaking (longitudinal discoloration of xylem vessels), black dots, necrosis and wood decay; occasionally, symptoms may appear in other organs of the plants as well (e.g. leaves and bunches) [6,7].