Incidence and Viability of Acremonium Endophytes in Tall Fescue and Meadow Fescue Plant Introductions

Abstract

Assessment of the infection status and viability of endophytic Acremonium spp. in USDA plant introductions (PI) of Festuca spp. would aid in identifying potentially desirable endophyte strains for improving pasture and turf species. The PI collection of tall fescue (F. arundinacea Schreb.) and meadow fescue (F. pratensis Huds.) was screened to determine Acremonium infection rate and viability. For tall fescue, 20 seed from each of 565 regenerated seedlots were microscopically examined for endophyte. Seventy‐nine accessions contained endophyte with an average infection frequency of 67.4%. Leaf sheaths of seedlings from the infected accessions were then examined to determine endophyte viability. Fifty‐five of the 79 infected accessions contained viable endophyte at an average infection frequency of 41.2% in the seedlings. The decline in the number of infected accessions and in their infection frequency suggested that loss in endophyte viability may have occurred in storage. More intensive analysis of 15 tall fescue accessions showed that endophyte infection declined from 68.4% in originally collected seed to 42.7% in regenerated seed to 23.6% in the seedlings from the regenerated seedlots, indicating diminishing endophyte occurrence and viability between the time of deposition of seed in the germplasm system and release of regenerated seed for general distribution. In meadow fescue, 29 of 198 accessions contained endophyte at 42.4% infection frequency in the seed and 31.6% infection frequency in the seedlings, indicating a proportionally lesser decline in endophyte viability than in tall fescue. While existing germplasm collections of Festuca spp. can provide Acremonium germplasm for study, newly collected Festuca germplasm will offer a greater diversity of Acremonium genotypes.