Abstract
The Hyphozyma synanamorph of Eleutheromyces subulatus causes black spot disease of the shiitake (.Lentinula edodes) fruiting body. Characteristic symptoms are the blackening and superficial lysis of infected pileus surface tissues. As a result of examining pathogenicity of the Hyphozyma synanamorph toward shiitake and other cultivated mushrooms, inoculation with yeastlike cells of the Hyphozyma synanamorph caused browning lesions only on shiitake, but not on other cultivated mushrooms. The culture filtrate of the yeastlike cells also caused browning lesions only on shiitake. These results suggest that the Hyphozyma synanamorph produces host-specific substances that cause browning lesions only on shiitake. Therefore, isolation of browning-inducing substances from culture filtrate of the Hyphozyma synanamorph was attempted. The browning-inducing activity was detected in a high molecular weight fraction (>10kDa) and was inactivated by treatment with 40℃ for 30 minutes. Following SDS-PAGE of the fraction, 15-16kDa and 37kDa bands were detected and the sequence of the same 15 N-terminal amino acids was determined. Because a protein homology search by BLAST did not identify any significant homology, these were inferred to be unknown proteins. This is the first report to show that the mushroom pathogenic fungus produces browning-inducing substances with host-specific activity.
