The Endophytic Fungus of Perennial Ryegrass

Summary In 1958 a survey was made of the incidence of the endophyte transmitted in certified perennial ryegrass seed ( Lolium perenne ) grown in New Zealand. Most lines of seed with high endophyte infection were strains harvested from long‐established pastures. There was a lower percentage of endophyte in certified perennial ryegrass lines of seed grown from pedigree‐bred strains of seed, and this appeared to be the result of loss of viability of the endophyte during seed storage in the early stage of multiplication of the seed. There was no endophytic infection in the seeds of short‐rotation ryegrass ( Lolium perenne × L. multiflorum ). The endophytic hyphae were abundant in the nucellar tissue of the ovary, and, with the development of the endosperm, the hyphae became restricted to the layer of crushed nucellus round the periphery of the aleurone cells in the mature caryopsis. Cultures of the endophyte grew best on ryecorn ( Secale cereale ) forming microconidia but no other spore‐bearing structures.