ABSTRACT A symbiosis between grasses and systemic fungal endophytes exists in both natural and ag... more ABSTRACT A symbiosis between grasses and systemic fungal endophytes exists in both natural and agricultural grassland communities. Our objective was to examine the effects of systemic endophytes on the competitive ability of two agronomically important grass species: meadow fescue [Festuca pratensis (Huds.) syn. Schedonorus pratensis (Huds.) P. Beauv] and tall fescue [Festuca arundinacea (Schreb.) syn. Schedonorus phoenix (Scop.)]. Plants of meadow and tall fescue were grown for 48 days in replacement series of interspecific mixture with a legume (red clover, Trifolium pratense L.) in different nutrient environments in a greenhouse. Neither of the grass species gained endophyte-promoted competitive advantage over red clover in grass–clover mixtures. Endophyte infection increased the growth of meadow fescue monocultures by 89% compared to endophyte-free monocultures in high-nutrient soils, but plant competition or the cost of endophyte infection to the meadow fescue decreased the yield in resource-limited conditions. On average, endophyte-infected and endophyte-free meadow fescues produced 0·15 and 0·17 g, and 0·14 and 0·14 g dry biomass per plant in mixtures with red clover in high- and low-nutrient soils respectively. In contrast to meadow fescue, endophyte-promoted growth of tall fescue monocultures was not detected. Endophyte-infected and endophyte-free tall fescue monocultures produced 0·76 and 0·95 g biomass per pot, respectively, in the high-nutrient environment. Endophyte infection can increase the performance of the host grass, but the positive effects depend on the host species, the species composition and soil nutrient availability.
ABSTRACT Exploring the regional pattern of variation in traits driven by symbiotic interactions m... more ABSTRACT Exploring the regional pattern of variation in traits driven by symbiotic interactions may provide insights to understand the evolutionary processes that operate over plant populations. Polyploidy, which is associated with fitness improvement, is expected to increase with latitude and altitude. However, it has never been explored in relation with the occurrence of epichloid fungal endophytes in plants. Both, variation in ploidy level and in the incidence of fungal endophytes, are known to occur in species of fine fescues. Here, we surveyed the occurrence of systemic fungal endophytes in natural Festuca vivipara populations in North European islands. In addition, we identified the fungal species associated with this grass and determined the predominant ploidy level for each population. Endophytes were found in four of six, two of three, and one of three populations for Faroe Islands, Iceland and Great Britain, respectively. With an average low incidence level of 15 % in infected populations, there was no relationship between infection level and either latitude or altitude. The phylogenetic analysis based on sequences ITS and the tub2 genes, supports that the endophytic species is Epichloë festucae, the same as in other fine fescues. We found no variation in ploidy level as all the plants were tetraploid (4X) with 28 chromosomes, a pattern which contrasts with the variation reported in previous antecedents. Our results suggest that apart from low and variable benefits of the endophyte to the plants, there would be a complex dynamics between epichloid endophytes and species of the fine fescue complex which merits further studies.
ABSTRACT A symbiosis between grasses and systemic fungal endophytes exists in both natural and ag... more ABSTRACT A symbiosis between grasses and systemic fungal endophytes exists in both natural and agricultural grassland communities. Our objective was to examine the effects of systemic endophytes on the competitive ability of two agronomically important grass species: meadow fescue [Festuca pratensis (Huds.) syn. Schedonorus pratensis (Huds.) P. Beauv] and tall fescue [Festuca arundinacea (Schreb.) syn. Schedonorus phoenix (Scop.)]. Plants of meadow and tall fescue were grown for 48 days in replacement series of interspecific mixture with a legume (red clover, Trifolium pratense L.) in different nutrient environments in a greenhouse. Neither of the grass species gained endophyte-promoted competitive advantage over red clover in grass–clover mixtures. Endophyte infection increased the growth of meadow fescue monocultures by 89% compared to endophyte-free monocultures in high-nutrient soils, but plant competition or the cost of endophyte infection to the meadow fescue decreased the yield in resource-limited conditions. On average, endophyte-infected and endophyte-free meadow fescues produced 0·15 and 0·17 g, and 0·14 and 0·14 g dry biomass per plant in mixtures with red clover in high- and low-nutrient soils respectively. In contrast to meadow fescue, endophyte-promoted growth of tall fescue monocultures was not detected. Endophyte-infected and endophyte-free tall fescue monocultures produced 0·76 and 0·95 g biomass per pot, respectively, in the high-nutrient environment. Endophyte infection can increase the performance of the host grass, but the positive effects depend on the host species, the species composition and soil nutrient availability.
ABSTRACT Exploring the regional pattern of variation in traits driven by symbiotic interactions m... more ABSTRACT Exploring the regional pattern of variation in traits driven by symbiotic interactions may provide insights to understand the evolutionary processes that operate over plant populations. Polyploidy, which is associated with fitness improvement, is expected to increase with latitude and altitude. However, it has never been explored in relation with the occurrence of epichloid fungal endophytes in plants. Both, variation in ploidy level and in the incidence of fungal endophytes, are known to occur in species of fine fescues. Here, we surveyed the occurrence of systemic fungal endophytes in natural Festuca vivipara populations in North European islands. In addition, we identified the fungal species associated with this grass and determined the predominant ploidy level for each population. Endophytes were found in four of six, two of three, and one of three populations for Faroe Islands, Iceland and Great Britain, respectively. With an average low incidence level of 15 % in infected populations, there was no relationship between infection level and either latitude or altitude. The phylogenetic analysis based on sequences ITS and the tub2 genes, supports that the endophytic species is Epichloë festucae, the same as in other fine fescues. We found no variation in ploidy level as all the plants were tetraploid (4X) with 28 chromosomes, a pattern which contrasts with the variation reported in previous antecedents. Our results suggest that apart from low and variable benefits of the endophyte to the plants, there would be a complex dynamics between epichloid endophytes and species of the fine fescue complex which merits further studies.
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Papers by S. Dirihan