Nonreciprocal Compatibility Between Epichloë Typhina and Four Host Grasses

ABSTRACT

The host ranges of Epichloë typhina isolates from four host grasses were investigated by reciprocal seedling inoculations. Isolates from Elymus villosus, E. virginicus, and Hystrix patula could infect seedlings of each of those hosts plus Brachyelytrum erectum seedlings. Isolates from B. erectum could infect only seedlings from its original host species. Isolates from E. virginicus were reisolated from B. erectum nearly 4 years after inoculation and found to be identical to the original E. virginicus isolate based on isozyme variation. This is the first case of cross-tribal infections by clavicipitaceous endophytes and the longest reported persistence of alien endophytes in a new host. Field population samples of sympatric Elymus species indicated that 40–50% of all plants were infected and that most infected plants produced both seed-bearing and stroma-bearing culms. These results indicate that there is considerable variation in host range among endophyte isolates and that compatibility relationships are not necessarily reciprocal. Variation in host range may be related to the degree of sympatry of hosts and the production of stromata on host plants.

Key Words:

• compatibility
• endophyte
• Epichloë typhina
• host range
• inoculations