Exploring endophyte diversity across the Pooideae
C. A. YOUNG (1), N. D. Charlton (1), J. E. Takach (1), G. A. Swoboda (1), B. A. Hall (1), K. D. Craven (1), M. E. Afkhami (2), T. Shymanovich (3), M. Oberhofer (3), S. H. Faeth (3), J. Rudgers (4), J. Pan (5), L. Chen (5), C. L. Schardl (5). (1) The Samuel Roberts Noble Foundation, Ardmore, OK, U.S.A.; (2) University of California-Davis, Davis, CA, U.S.A.; (3) University of North Carolina-Greensboro, Greensboro, NC, U.S.A.; (4) University of New Mexico, Albuquerque, NM, U.S.A.; (5) University
Cool season grasses from the subfamily Pooideae have extremely wide distributions, inhabiting many different ecological niches. For some, their success can be attributed to fungal symbiotic partners known collectively as the epichloae (<i>Epichloë</i> and <i>Neotyphodium</i> species). The epichloae can produce a range of bioactive alkaloids (ergot alkaloids, indole-diterpenes, lolines and peramine) and exhibit considerable chemotypic diversity within these biosynthetic pathways that likely equates to fitness benefits to the host. A high throughput pipeline was established to rapidly evaluate endophyte incidence, species identification and potential bioactivity across grass collections representing multiple host tribes. Total DNA isolated from seed or tillers are genotyped with markers designed to key alkaloid biosynthesis genes and mating type genes to determine endophyte diversity among and between grass populations. Phylogenetic analyses of housekeeping and mating-type genes inferred hybrid versus nonhybrid origins and hybrid ancestral progenitors. Sequence analyses of alkaloid genes encoding key pathway steps provide copy number and progenitor origins. Multiple endophyte species were found to associate independently with some grass hosts. The diverse evolutionary histories identified within the collections provide insight into the broader ecological implications of endophyte-plant symbioses.
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