Broad-scale variation in the incidence of fungal endophytes in temperate grasses

SEMMARTIN, M.; OMACINI M; GUNDEL, PE; HERNÁNDEZ-AGRAMONTE I.

JOURNAL OF APPLIED ECOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2015 vol. 103 p. 184 - 190

0021-8901

1. The strength of many interactions between plants and other organisms changes across regionalgradients. For example, the relevance of plant-herbivore interactions increases with primary production.Likewise, biotic interactions collectively become more intense from the poles to the equator.Yet, the regional variation of the interaction between grasses and systemic fungal endophytes, whichprovide resistance to biotic and abiotic environmental factors (i.e. herbivory and drought), is poorlyunderstood.2. We compiled 1008 records of the incidence level of fungal endophytes (Epichlo?e, Ascomycetes:Clavicipitaceae) on wild populations of 48 cool season grasses, encompassing 10 biomes across abroad latitudinal expanse and primary production gradient. Symbiosis incidence was analysed as afunction of mean primary production, precipitation, temperature and latitude of each site, which inturn were obtained from climatic and satellital sources.3. Across a 30-fold variation of mean primary production, average symbiosis incidence increasedfrom 20% to 70%. The pattern became stronger when the analysis was restricted to the single grassgenus Festuca, which accounted for half of the total data.4. The number of grass populations showing no symbiosis incidence (0%) decreased as primary productionincreased, whereas those with 100% of incidence increased.5. Primary production at the regional scale was negatively correlated with latitude but positivelywith mean annual temperature and precipitation. Symbiosis incidence was similarly correlated withlatitude and temperature, and it was not with mean annual precipitation.6. Synthesis. Different descriptors of this grass-fungus symbiosis show that average incidence inwild populations world-wide increases with mean primary production. As at large spatial scales herbivoryand temperature increase and aridity decreases with primary production, our results suggestthat, at broad-scales, these biotic and abiotic factors may be important drivers of the symbiosis success.