Black spot disease of Lentinula edodes caused by the Hyphozyma synanamorph of Eleutheromyces subulatus

Abstract

The Hyphozyma synanamorph of Eleutheromyces subulatus was found to be the cause of black spot disease of Lentinula edodes fruiting bodies. Multiplication of yeastlike cells and hyphae of Hyphozyma resulted in blackening and mild lysis of the infected host cap tissues where partially degraded skeletal microfibrils of host cell walls were abundant. In general, host tissue lysis remained superficial; however in some cases, Hyphozyma caused severe lysis and formed deep cavities containing remnants of highly dissolved host cell walls and numerous yeastlike cells of the pathogen. Enzyme assays demonstrated the ability of Hyphozyma to produce both chitinase and β-(1,3) glucanase enzymes, requirements for hyphal wall degradation. On agar, conidiogenesis is enteroblastic in the Hyphozyma morph, whereas it is apparently holoblastic in the Eleutheromyces morph. No evidence of phialidic conidiogenesis was obtained.

Key Words:

• chitinase
• electron microscopy
• hyphomycete
• pathogen
• shiitake mushroom