Incidence and diversity of Neotyphodium fungal endophytes in tall fescue from Morocco, Tunisia, and Sardinia

There is a premium on having Neotyphodium germplasm available for temperate grass improvement programs because these fungal endophytes present opportu nities for developing new grass-endophyte combinations for enhanced toleran ce to abiotic and biotic stresses. Unfortunately; surveys have revealed a l ow incidence of Neotyphodium fungi in grass germplasm collections, This res earch surveyed tall fescue (Festuca arundinacea Schreb,) accessions from a 1994 Australian-U.S. plant-collection trip to Morocco, Tunisia, and Italy ( Sardinia) for viable Neotyphodium fungi and determined whether infected acc essions harbor different Neotyphodium genotypes. Conidial measurements of i solates cultured on agar and bioassays of die differential survival of bird cherry-oat aphid [Rhopalosiphum padi (L.)] on infected accessions were use d to characterize Neotyphodium diversity. A secondary objective determined the consistency of a polymerase chain reaction (PCR) method to detect Neoty phodium fungi in fall, fescue. Neotyphodium was detected in 336 of 439 plan ts (76.5%) distributed among 104 accessions, of which 99 were endophyte-inf ected, Mean conidial lengths of 42 isolates ranged from 3.91 to 9.91 mum. M ost of the isolates (71.4%) had conidia with mean lengths smaller than the lower limit (6.5 pm) characteristic of the tall fescue endophyte N. coenoph ialum (Morgan-Jones and Gems) Glenn, Bacon, and Hanlin. In aphid assays, ah endophyte-free plants were susceptible to R, padi and all but two infected plants were resistant to this aphid, Thus, a Mediterranean plant-collectio n trip secured diverse Neotyphodium endophytes in tall fescue for storage i n seed brinks, and a PCR assay defected Neotyphodium in tall fescue plants of diverse geographical origin.