Identification of epiphyllous mycelial nets on leaves of grasses infected by clavicipitaceous endophytes

Fungal endophytes of genus Neotyphodium have long been known to inhabit the internal tissues of plants without producing external reproductive structu res on plants. For these endophytes, infection of the embryo within the see d has been the accepted mode of transmission. In this study, we examined se veral species of endophyte-infected grasses, including Bromus setifolius, F estuca ovina, F. rubra, and Poa ampla, and documented the presence of epiph yllous mycelial nets on their leaves. To evaluate whether the epiphyllous n ets originated from the endophytes, we isolated the epiphyllous mycelium fr om the surfaces of Poa ampla leaves and analyzed it by DNA sequencing and m icroscopy. DNA sequencing demonstrated that the epiphyllous net originated from the endophyte, Neotyphodium typhinum. Conidial production on the epiph yllous mycelium suggests that the endophyte may have the opportunity for co ntagious spread to uninfected plants through epiphyllously-produced conidia . The mycelial nets produced by clavicipitaceous endophytes may also play a role in defense of host plants from potential pathogens through 'niche exc lusion'.