Mansonone accumulation in elm callus induced by elicitors of Ophiostoma ulmi, and general properties of elicitors
Fungal culture filtrates, cytoplasm, and cell walls of Ophiostoma ulmi contain molecules that elicit mansonone (phytoalexin) accumulation in elm calli. The elicitors from nonaggressive isolate Q311 cause a more rapid reaction on bioassays than those from the aggressive isolate MH75. On the callus of a susceptible elm (Ulmus americana), the elicitors from both isolates cause higher amounts of mansonone production than on the callus of a resistant elm (Ulmus pumila). These elicitors are heat stable, and their eliciting activities are partially sensitive to NaIO4, pronase E, proteinase K, and various hydrolytic enzymes. However, β-glucosidase treated elicitors have increased eliciting activities. The binding of Q311 culture filtrate elicitors to a concanavalin A – sepharose 4B column suggests that glycoproteins may be involved in elicitation. Some abiotic factors stimulate only small amounts of mansonone F accumulation in treated elm cells.