Schirrmann M.K. & Leuchtmann A. (2015), The role of host-specificity in the reproductive isolation of Epichloë endophytes revealed by reciprocal infections, in Fungal Ecology
, 15, 29-38.
Schirrmann M.K. Zoller S. Fior S. & Leuchtmann A. (2014), Genetic evidence for reproductive isolation among sympatric Epichloë endophytes as inferred from newly developed microsatellite markers, in Microbial Ecology (online)
Leuchtmann A. Bacon C. W. Schardl C. L. White J. F. Jr. and Tadych M. (2014), Nomenclatural realignment of Neotyphodium species with genus Epichloë, in Mycologia
, 106(2), 202-215.
LEUCHTMANN A. & STEINEBRUNNER F. (2012), Evidence for reproductive isolation in Epichloë species: a case study, in YOUNG C. A. AIKEN G. E MCCULLEY R. L. STRICKLAND J. R. AND SCHARDL C. L. (ed.), The Samuel Roberts Noble Foundation, Ardmore Oklahoma, USA, 113-116.
Speciation is one of the most fundamental processes in biology that leads to biological diversity. However, the mechanisms of speciation are variable in different organisms and still incompletely known. Particularly in members of Fungi, one of the most species rich kingdoms, they are largely unexplored. Species of genus Epichloë (Ascomycota, Clavicipitaceae) are wide-spread endophytes of pooid grasses. At sexual reproduction, they form external fruiting structures (stromata) that partially or completely inhibit host flowering and seed production (known as ‘choke disease’). Epichloë species have a bipolar self-incompatibility mating system requiring transfer of male gametes (spermatia) which is usually accomplished by specialized flies of the genus Botanophila in a process similar to pollination. The 11 species described so far are recognized mostly based on a biological species concept and on restricted distribution and host range. In addition to the formally described species, molecular phylogenetic evidence suggest that several cryptic species exist that may occur sympatrically on different host grasses. Epichloë endophytes with its sexual species complexes offer an ideal model system on which mechanisms of reproductive isolation, a prerequisite of speciation, can be studied. The planned research will investigate several potential pre- and post zygotic isolation mechanisms that may operate among members of a species complex including two interfertile morphological species (E. typhina and E. clarkii) and several host-associated cryptic species. With a series of experiments we hope to answer the following research questions:1) Are spermatia from different species recognized and/or competing among each other on the stroma before fertilization (assortive mating)?2) Do hybrids suffer from inviability or reduced compatibility with parental hosts (post zygotic isolation)? 3) Are host plants infected with hybrid strains less fit?Results of the study will deepen our understanding of the mechanisms of reproductive isolation in fungi, and eukaryote speciation in general. The proposed research is relevant also for applied aspects of endophyte research. Epichloë endophytes are of economic importance in agriculture and turf grass industry. Biotechnological exploitation and control of endophytes relies on basic knowledge including insights coming from evolutionary ecology studies.