Suchergebnisse

8 páginas, 2 tablas, 2 figuras. -- The final publication is available at www.springerlink.com ; Epichloë festucae is an endophytic fungus that infects systemically the aerial tissues of the host grass Festuca rubra. This fungus is transmitted vertically from the mother plant to seeds. Hypothetically, the presence of E. festucae could affect the infection of a plant by other fungal species. This could occur if E. festucae metabolites produced in planta interfere negatively with other fungal infections; or alternatively, if the modulation of plant defenses by the endophyte favour further fungal infections. We have analyzed the presence of culturable non-systemic endophytes in plants of F. rubra infected (E+) and not infected (E-) by E. festucae in two subarctic habitats, meadows and riverbanks in Northern Finland. The observed non-systemic endophyte infection frequencies were similar among E+ and E- plants from riverbanks, and E+ plants from meadows. In contrast to these, the infection frequency was significantly lower in E- plants from meadows. This result suggests that the presence of E. festucae is not a main factor determining the presence of non-systemic endophytes in plants. Instead, plant genetic characteristics related to compatibility with E. festucae and other endophytes in the more stable meadow populations might play a role in these fungus-fungus-plant interactions. As a result of the survey, 18 different taxa of non-systemic endophytes were identified in plants of F. rubra. All were ascomycetes except for one basidiomycete. Three endophytic taxa could not be ascribed to a genus, but sequence data indicated that they were conspecific with other unidentified endophytes that have been isolated in cold biomes at different locations. ; The research leading to these results has received funding from INTERACT (grant agreement No. 262693) under the European Community's Seventh Framework Programme, from Academy of Finland (Project No. 137909), and Spanish Government (Project AGL2011-22783) ; Peer reviewed

9 páginas, 2 tablas, 2 figuras ; Plants host taxonomically and functionally complex communities of microbes. However, ecological studies on plant-microbe interactions rarely address the role of multiple co-occurring plant-associated microbes. Here, we contend that plant-associated microbes interact with each other and can have joint consequences for higher trophic levels. In this study we recorded the occurrence of the plant seed pathogenic fungus Claviceps purpurea and aphids (Sitobion sp.) on an established field experiment with red fescue (Festuca rubra) plants symbiotic to a seed transmitted endophytic fungus Epichloë festucae (E+) or non-symbiotic (E-). Both fungi are known to produce animal-toxic alkaloids. The study was conducted in a semi-natural setting, where E+ and E- plants from different origins (Spain and Northern Finland) were planted in a randomized design in a fenced common garden at Kevo Subarctic Research Station in Northern Finland. The results reveal that 45% of E+ plants were infected with Claviceps compared to 31% of E- plants. Uninfected plants had 4.5 times more aphids than Claviceps infected plants. By contrast, aphid infestation was unaffected by Epichloë symbiosis. Claviceps alkaloid concentrations correlated with a decrease in aphid numbers, which indicates their insect deterring features. These results show that plant mutualistic fungi can increase the infection probability of a pathogenic fungus, which then becomes beneficial to the plant by controlling herbivorous insects. Our study highlights the complexity and context dependency of species-species and multi-trophic interactions, thus challenging the labeling of species as plant mutualists or pathogens. ; This work was supported by the Academy of Finland (KS, Grant Nos. 295976 and 326226; MH, Grant No. 311077; BF, Grant No. 324523), the Spanish Ministry of Science and Innovation and FEDER grant PID2019-109133RB-I00, and from the project CLU-2019-05—IRNASA/CSIC Unit of Excellence funded by Junta de Castilla y León and cofinanced by the European Union (ERDF Europe drives our growth). ; Peer reviewed