Diversity, ecology and applications of Epichloë fungal endophytes of grasses in South America

IANNONE, L.J.; NOVAS, M.V.; MC CARGO, P.D.; UENO, A.C. ; GUNDEL, P.E.

Neotropical endophytic fungi Diversity, Ecology, and Biotechnological Applications

Springer Science

Lugar: Berlin ; Año: 2020; p. 1 - 130

Epichloë fungal endophytes are a conspicuous group of fungi (Ascomycota, Hypocreales, Clavicipitaceae) that form persistent symbiosis with certain cool-season grasses (Pooideae) worldwide. The symbiosis is not vital for the plants, but it seems to be associated with fitness benefits, a basic condition for being favorably selected. Epichloë endophytes infect systemically green tissues, and while sexual stages reduce fertility of the host plant, their asexual forms persist asymptomatically through generations by means of vertical transmission (from plant to seeds). Host plants are endowed by a suite of fungal alkaloids that can be toxic to livestock (such as ergot alkaloids and lolitrem B) or protect plants against herbivorous insects (lolines and peramine). Mainly studied in the Northern Hemisphere, where species with sexual or asexual stages are found, Epichloë in South America appears to present its own characteristics. Only asexual vertically transmitted Epichloë has been detected in South America from Venezuela to Argentina. Although research in genetic biodiversity of Epichloë fungi in South America is in the dawn and mostly restricted to Argentina, we know that most of the endophytes from South America evolved from hybridization events among species from the Northern Hemisphere not found in this region. Interestingly, a few strains or fungal species are associated to more than one host grass species, which contrasts with what is known from the Northern Hemisphere. Regional surveys of grass-endophyte associations indicate that some environmental conditions promote the symbiosis while others don?t (e.g., aridity). However, variation among closely related plant species also evidences phylogenetic constrains. Fungal endophytes are being used in breeding programs of forage crops with two main goals: (i) replace those wild toxic endophytes and (ii) inoculate endophytes that protect host plants against agricultural plagues (as agents of biological control). The knowledge of the diversity of Epichloë fungi, the host grasses they infect, and the ecophysiological impact on plant fitness opens a big potential to advance eco-friendly tools for the development of a more sustainable agriculture.