Clavicipitaceous anamorphic endophytes in Hordeum germplasm
The incidence of clavicipitaceous anamorphic endophytes, non-choke inducing endosymbiotic fungi of the genus Neotyphodium that systemically infect grasses, in eighteen Hordeum species from the U.S. National Plant Germplasm System was examined using light and Scanning Electron Microscopy (SEM). Seventeen plant inventory accessions from only three Hordeum species, including H. bogdanii, H. brevisubulatum subsp. violaceum and H. comosum, were found to contain significant levels of seed and seedling infection ranging from 18-99%. Neotyphodium-endophytes were found in Hordeum germplasm from one country (Argentina) in South America and four countries (Afghanistan, China, Iran and Kazakhstan) in Asia. The viability of endophytic mycelium in seeds was confirmed by culturing these fungi on potato dextrose agar medium from aleurone tissue of seeds and by direct observations of hyphae in leaf sheaths of 3-4 week-old seedlings. Morphological characteristics of these fungi were further characterized using SEM to determine similarities and differences in conidiophores and conidia produced in culture. The importance, significance and potential benefits of Neotyphodium-endophytes from wild Hordeum as sources of insect resistance in cultivated barley, other cereal grasses and in wild grasses included in the Conservation Reserve Program are discussed. Suggested strategies for the proper maintenance of this valuable germplasm also are elucidated.