Incidence and compatibility of nonclavicipitaceous fungal endophytes in Festuca and Lolium grass species

Abstract

The p-endophytes, previously identified as Gliocladium-iike and Phialophora-like fungi, constitute a group of closely related, seed transmissible grass symbionts which have been found in several Festuca species and Lolium perenne, most often in cosymbiosis with mutualistic Epichloë-type (Acremonium) endophytes (e-endophytes). To help assess the ecological importance of p-endophytes, their incidence and the incidence of e-endophytes was determined in seed accessions of Festuca and Lolium grass species in the U. S. Department of Agriculture Plant Introduction collection. Ten seeds of each accession were tested by tissue print immunoblot assay for the presence of e- or p-endophytes in separate seeds, or together in individual seeds. A total of 370 accessions from 36 Festuca species and five Lolium species were tested. The e-endophytes were present in 25 of the Festuca species and all of the Lolium species, while the p-endophytes appeared in five and one species, respectively. The p-endophytes were present in 18 Festuca accessions and six Lolium accessions, while the e-endophytes appeared in 121 and 43 accessions, respectively. The p- and e-endophytes were detected together in individual seeds in a total of five species and 13 accessions from both genera. Infectivity studies indicated that when p-endophytes from different species were introduced into their own and reciprocal hosts only the endophytes introduced into their own hosts produced significant levels of sustainable infections. Three conclusions were inferred from this study: 1) The previously reported abundance of e-endophytes in Fesuca and Lolium grasses was substantiated. 2) Symbiosis of p-en- dophytes, as indicated by seed dissemination, is not as common in these grasses as e-endophyte symbiosis, suggesting that the p-endophytes are less ecologically important to the grasses, and may not be mutualists (they may be commensal or agonists). 3) Genotypes of p-endophytes can be host specific.

Key Words:

• Acremonium
• endophytes
• Epichloë
• Festuca
• Gliocladium-like endophytes
• grasses
• incidence
• infectivity
• Lolium
• Phialophora-like endophytes