000164097 001__ 164097 000164097 005__ 20251121161351.0 000164097 0247_ $$2doi$$a10.3897/imafungus.16.162692 000164097 0248_ $$2sideral$$a146195 000164097 037__ $$aART-2025-146195 000164097 041__ $$aeng 000164097 100__ $$aSotomayor-Alge, Alba$$uUniversidad de Zaragoza 000164097 245__ $$aUnveiling an asymmetric plant–fungal symbiosis: morphological, cytogenetic, and molecular characterization of a haploid Epichloë festucae strain associated with three polyploid cytotypes of the Iberian endemic grass Festuca rothmaleri 000164097 260__ $$c2025 000164097 5060_ $$aAccess copy available to the general public$$fUnrestricted 000164097 5203_ $$aThe ecological and evolutionary outcomes of plant–fungal interactions are strongly influenced by genome size and ploidy, yet the ploidy level of both partners is rarely assessed simultaneously. Epichloë symbioses with Pooideae grasses are established model systems for exploring these dynamics, but associations between polyploid hosts and haploid endophytes remain poorly documented. In this study, the association of the Iberian endemic Festuca rothmaleri—which includes tetraploid, hexaploid, and octoploid cytotypes—with Epichloë fungal endophytes is documented for the first time. An integrative, method-rich framework combining cytogenetics, morphometrics, and multilocus phylogenetics revealed a strikingly asymmetric interaction, with all cytotypes harboring a single haploid strain of Epichloë festucae. Two methodological innovations were developed: (i) an image-based tool for automated measurement of asexual structures, including the novel metric “conidial area,” and (ii) a flow cytometry protocol for estimating fungal genome size. Despite morphological variability, all fungal isolates shared similar genome sizes and formed a well-supported monophyletic lineage in a coalescent species tree based on nuclear loci sequences (actG, CalM, ITS, tefA, tubB). This work provides the first comprehensive characterization of a haploid Epichloë endophyte spanning multiple naturally distributed host ploidy levels and highlights a rare but promising system for future evolutionary, physiological, and ecological studies of plant–fungal interactions. 000164097 536__ $$9info:eu-repo/grantAgreement/ES/DGA-FSE/A01-23R$$9info:eu-repo/grantAgreement/ES/MICINN/PDC2022- 133712-I00$$9info:eu-repo/grantAgreement/ES/MICINN/PID2022-140074NB-I00$$9info:eu-repo/grantAgreement/EUR/MICINN/TED2021-131073B-I00 000164097 540__ $$9info:eu-repo/semantics/openAccess$$aby$$uhttps://creativecommons.org/licenses/by/4.0/deed.es 000164097 655_4 $$ainfo:eu-repo/semantics/article$$vinfo:eu-repo/semantics/publishedVersion 000164097 700__ $$0(orcid)0000-0002-1214-375X$$aInda, Luis A.$$uUniversidad de Zaragoza 000164097 700__ $$aBeamonte, Ernesto Ángel 000164097 700__ $$aZabalgogeazcoa, Íñigo 000164097 700__ $$0(orcid)0000-0002-4147-6895$$aCatalán, Pilar 000164097 7102_ $$15011$$2063$$aUniversidad de Zaragoza$$bDpto. CC.Agrar.y Medio Natural$$cÁrea Botánica 000164097 773__ $$g16 (2025), e162692 [28 pp.]$$pIMA fungus$$tIMA fungus$$x2210-6340 000164097 787__ $$tUnveiling an asymmetric plant–fungal symbiosis: morphological, cytogenetic, and molecular characterization of a haploid Epichloë festucae strain associated with three polyploid cytotypes of the Iberian endemic grass Festuca rothmaleri$$tFrothmaleriEpichloe$$whttps://datadryad.org/dataset/doi:10.5061/dryad.hx3ffbgsb$$whttps://github.com/Bioflora/FrothmaleriEpichloe 000164097 8564_ $$s4274156$$uhttps://zaguan.unizar.es/record/164097/files/texto_completo.pdf$$yVersión publicada 000164097 8564_ $$s2375367$$uhttps://zaguan.unizar.es/record/164097/files/texto_completo.jpg?subformat=icon$$xicon$$yVersión publicada 000164097 909CO $$ooai:zaguan.unizar.es:164097$$particulos$$pdriver 000164097 951__ $$a2025-11-21-14:26:26 000164097 980__ $$aARTICLE