Susceptibility of endophyte-infected grasses to winter pathogens (snow molds)

Abstract

Neotyphodium endophytes are suggested to be mutualistic symbionts of grasses and regarded as potential biological plant protection agents. We examined the effects of the Neotyphodium endophyte of meadow ryegrass on snow molds in vitro with dual cultures of endophyte and Typhula ishikariensis , and on grass–snow mold interactions in vivo in a greenhouse and in a field experiment. In dual cultures, the endophytes formed an inhibition zone and retarded the growth of T. ishikariensis. In the field experiment, however, the endophyte-infected (E+) meadow ryegrasses were more susceptible to T. ishikariensis than the endophyte-free (E–) grasses. Endophyte infection increased the winter damage of grasses both in greenhouse and in field conditions. After winter, the growth of E+ grasses exceeded the growth of E– plants in the field experiment, indicating the marked tolerance of E+ grasses against winter damage. We detected differences in growth and pathogenesis between the different T. ishikariensis strains and found meadow ryegrass cultivar–endophyte status interaction in the growth of meadow ryegrasses, which highlight the effects of the genetic background of the participants on endophyte–grass–snow mold interactions.