RT Journal Article T1 No priming, just fighting – endophytic yeast attenuates the defense response and the stress induced by Dutch elm disease in Ulmus minor A1 Sobrino Plata, Juan A1 Martínez-Arias, Clara A1 Ormeño-Moncalvillo, Sara A1 Fernández, Iván A1 Collada, Carmen A1 Gil, Luis A1 Pieterse, Corne A1 Martín, Juan Antonio AB One century after the first report of Dutch elm disease (DED), there is still no practical solution for this problem threatening European and American elms (Ulmus spp.). The long breeding cycles needed to select resistant genotypes and the lack of efficient treatments keep disease incidence at high levels. In this work, the expression of defense-related genes to the causal agent of DED, Ophiostoma novo-ulmi Brasier, was analyzed in in vitro clonal plantlets from two DED-resistant and two DED-susceptible Ulmus minor Mill. trees. In addition, the effect of the inoculation of an endophytic pink-pigmented yeast (Cystobasidium sp.) on the plant’s defense system was tested both individually and in combination with O. novo-ulmi. The multifactorial nature of the resistance to DED was confirmed, as no common molecular response was found in the two resistant genotypes. However, the in vitro experimental system allowed discrimination of the susceptible from the resistant genotypes, showing higher levels of oxidative damage and phenolic compounds in the susceptible genotypes after pathogen inoculation. Inoculation of the endophyte before O. novo-ulmi attenuated the plant molecular response induced by the pathogen and moderated oxidative stress levels. Niche competition, endophyte–pathogen antagonism and molecular crosstalk between the host and the endophyte are discussed as possible mechanisms of stress reduction. In sum, our results confirm the complex and heterogeneous nature of DED resistance mechanisms and highlight the possibility of using certain endophytic yeasts as biological tools to improve tree resilience against biotic stress. SN 0829-318X YR 2022 FD 2022 LK https://hdl.handle.net/20.500.14352/99652 UL https://hdl.handle.net/20.500.14352/99652 LA eng NO J Sobrino-Plata, C Martínez-Arias, S Ormeño-Moncalvillo, I Fernández, C Collada, L Gil, C M J Pieterse, J A Martín, No priming, just fighting—endophytic yeast attenuates the defense response and the stress induced by Dutch elm disease in Ulmus minor Mill., Tree Physiology, Volume 42, Issue 10, October 2022, Pages 2086–2099, https://doi.org/10.1093/treephys/tpac062 NO Ministerio de Economía y Competitividad (España) NO Ministerio de Agricultura, Pesca y Alimentación (España) NO Universidad Politécnica de Madrid DS Docta Complutense RD 4 abr 2025