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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

8 páginas, 2 figuras. -- The original publication is available at www.springerlink.com ; Two endophytic strains of the entomopathogenic fungus Tolypocladium cylindrosporum, originally isolated from the grass Festuca rubra, were artificially inoculated in tomato and bean plants. Strains 11-1L and 11-0BR were isolated from asymptomatic leaf fragments of both plant species at 3, 7, 14, 21, and 35 days after their inoculation. The percentage of leaf fragments infected by the fungus in inoculated leaves decreased at each sampling time, and no systemic colonization of the plants occurred. The two T. cylindrosporum strains tested were isogenic, differing in the infection by the victorivirus TcV1, harboured by strain 11-1L, but not by 11-0BR. The percentage of infected leaf fragments in leaves inoculated with the virus infected strain was greater in bean than in tomato plants, while the virus-free strain was more successful in tomato than in bean plants. This result suggests that the mycovirus infection can affect the adaptation of T. cylindrosporum to particular host plants. ; This work was financed with research grant AGL2008-01159, awarded by the Spanish Government ; Peer reviewed

15 páginas, 2 tablas, 6 figuras. - The final publication is available at www.springerlink.com ; Grasses represent one of the Earth's most common plant groups, and natural and cultivated habitats dominated by grasses cover about 40% of the land surface. In turn, each grass species hosts multiple fungal species which can behave as endophytes. An analysis of the endophytic taxa identified in surveys conducted in 14 grass species showed that some of the most frequent taxa on each grass were also present across several host grasses. These taxa were Alternaria, Epicoccum, Cladosporium, Fusarium, and a few others. A similar analysis of airborne fungi surveyed at 41 different locations throughout the world showed that some of the most geographically widespread, and most locally frequent airborne fungi belonged to the same genera that are dominant endophytes in grasses (i.e. Cladosporium, Alternaria, Fusarium, etc.). Therefore, airborne spores of genera that are ubiquitous in grasses are common worldwide and attain high atmospheric concentrations. In addition, spores of the above mentioned fungi are also important respiratory allergens. Direct observation indicates that saprobic colonization and sporulation of non-systemic grass endophytes could become unrestrained when their host plant tissue dies. Subsequently, when appropriate environmental conditions favour sporulation on grass host surfaces, the natural cycle for airborne conidia initiates, and large numbers of these conidia disperse as inoculum for new endophytic infections. Therefore, the cycle of endophytism may be an important link between climate, plant biology and public health. ; This work was funded by Project AGL2011-22783, granted by the Spanish Government. We thank members of COST Action FA1103. ; Peer reviewed

10 páginas, 5 tablas, 5 figuras ; Tolypocladium cylindrosporum is a fungus which has been isolated from soil, from asymptomatic plants as an endophyte, and has been shown to be pathogenic to several species of arthropods. The objective of the present work was to study a collection of T. cylindrosporum strains in order to evaluate the characteristics of this fungus as a bioacaricide. The pathogenicity of five different strains of T. cylindrosporum was tested against two tick species, Ornithodoros erraticus and Ornithodoros moubata. Both tick species were susceptible to all the fungal strains. Mortality was greater for O. erraticus, and differed among the five developmental stages of the ticks tested, and among the fungal treatments. Mean mortality rates were close to 60% for O. erraticus, similar to those reported for other entomopathogenic fungi used for this purpose. The responses of eleven different strains of the fungus to 22ºC and 30ºC were also studied. Significant differences in temperature tolerance occurred among the strains, and growth inhibition was observed at 30ºC. Several mycoviruses were found infecting five of the eleven strains. However, no clear relationship was found between the presence of viruses and fungal growth or pathogenicity. ; This work was financed with research grants AGL2008-01159AGR, awarded by the Spanish Government,and CSI07A08, awarded by the Regional Government of Castilla y León (Spain). ; Peer reviewed

15 páginas, 8 figuras, 1 tabla ; SpainFestuca rubra subsp. pruinosa is a perennial grass that inhabits sea cliffs, a habitat where salinity and low nutrient availability occur. These plants have a rich fungal microbiome, and particularly common are their associations with Epichloë festucae in aboveground tissues and with Fusarium oxysporum and Periconia macrospinosa in roots. In this study, we hypothesized that these fungi could affect the performance of F. rubra plants under salinity, being important complements for plant habitat adaptation. Two lines of F. rubra, each one consisting of Epichloë-infected and Epichloë-free clones, were inoculated with the root endophytes (F. oxysporum and P. macrospinosa) and subjected to a salinity treatment. Under salinity, plants symbiotic with Epichloë had lower Na+ content than non-symbiotic plants, but this effect was not translated into plant growth. P. macrospinosa promoted leaf and root growth in the presence and absence of salinity, and F. oxysporum promoted leaf and root growth in the presence and absence of salinity, plus a decrease in leaf Na+ content under salinity. The growth responses could be due to functions related to improved nutrient acquisition, while the reduction of Na+ content might be associated with salinity tolerance and plant survival in the long term. Each of these three components of the F. rubra core mycobiome contributed with different functions, which are beneficial and complementary for plant adaptation to its habitat in sea cliffs. Although our results do not support an obvious role of Epichloë itself in FRP salt tolerance, there is evidence that Epichloë can interact with root endophytes, affecting host plant performance ; This study has received funding from the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement no. 676480 and from the project "CLU-2019-05 – IRNASA/CSIC Unit of Excellence," funded by the Junta de Castilla y León and co-financed by the European Union (ERDF "Europe drives our growth"). ; Peer reviewed

14 páginas, 6 tablas, 7 figuras. -- The first publication by Frontiers Media is avalilable at https://www.frontiersin.org/articles/10.3389/fmicb.2018.03321/full ; Festuca rubra subsp. pruinosa is a perennial grass that inhabits sea cliffs of the Atlantic coasts of Europe. In this unhospitable environment plants grow in rock crevices and are exposed to abiotic stress factors such as low nutrient availability, wind, and salinity. Festuca rubra subsp. pruinosa is a host of the fungal endophyte Epichloë festucae, which colonizes aerial organs, but its root mycobiota is unknown. The culturable endophytic mycobiota of FRP roots was surveyed in a set of 105 plants sampled at five populations in marine cliffs from the northern coast of Spain. In total, 135 different fungal taxa were identified, 17 of them occurred in more than 10% of plants and in two or more populations. Seven taxa belonging to Fusarium, Diaporthe, Helotiales, Drechslera, Slopeiomyces, and Penicillium appeared to be constituents of the core microbiome of Festuca rubra subsp. pruinosa roots because they occurred in more than 20% of the plants analyzed, and at three or more populations. Most fungal strains analyzed (71.8%) were halotolerant. The presence of Epichloë festucae in aboveground tissue was detected in 65.7% of the plants, but its presence did not seem to significantly affect the structure of the core or other root microbiota, when compared to that of plants free of this endophyte. When plants of the grass Lolium perenne were inoculated with fungal strains obtained from Festuca rubra subsp. pruinosa roots, a Diaporthe strain significantly promoted leaf biomass production under normal and saline (200 mM NaCl) watering regimes. These results suggest that the core mycobiome of Festuca rubra subsp. pruinosa could have a role in host plant adaptation, and might be useful for the improvement of agricultural grasses. ; This study has received funding from the European Union's Horizon 2020 Research and Innovation Program under theMarie Skłodowska-Curie grant agreement no. 676480. LS was funded through a Talent Recruitment grant from "Obra Social La Caixa– Fundación CAN". We acknowledge support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI). ; 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