Submitted to: Symbiosis
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/27/2001
Publication Date: 2/19/2002
Citation: Dugan, F.M., Sitton, J.W., Sullivan, R.F., White, J.F. 2002. The neotyphodium endophyte of wild barley (hordeum brevisubulatum subsup. violaceum) grows and sporulates on leaf surfaces of the host.. Symbiosis. 32: 147-159. Interpretive Summary: Fungi in the genus Neotyphodium are known to exist as symbionts of various grass family plants. These fungi are important largely because they can render the grass host toxic to grazing animals or insects, an effect whose desirability is contingent on the purpose for which the grass is grown. Although it was conventional wisdom that Neotyphodium species grew only inside grass tissues, recent investigations have discovered that some species may also grow on the surface of their hosts, and even sporulate there. Our studies have confirmed that this is the case for the Neotyphodium endophyte of wild barley. The degree to which it grows and sporulates on the surface is intermediate between Neotyphodium species which grow and sporulate prolifically on a host surface, and those which do neither. Any production of spores on the host surface challenges the previous conventional wisdom that Neotyphodium fungi propagated themselves only through the seed or tillers of their hosts.
Technical Abstract: The Neotyphodium endophyte of wild barley (Hordeum brevisubulatum subsp.violaceum) has been demonstrated via stained leaf impressions, SEM, and the plating to agar media of leaf washes from the host, to grow and sporulate on leaf surfaces under laboratory conditions. Superficial mycelium was usually sparse, and mycelial nets were not observed on the leaf epidermis. ITS sequence data were identical for Neotyphodium isolates derived from surface-disinfested leaf tissue and from leaf washes. Conidia of the endophyte were capable of germination and growth on nutrient agar.