Pleurotus Ostreatus - breeding potential of a new cultivated mushroom.

Two isolates of Pleurotus ostreatus from North America and one from Germany are interbreedable. Under identical conditions at low temperatures, their fruiting bodies are hard to distinguish. However, shape and colour and several other characters vary with culture conditions. The American stocks fruit well at temperatures from 4 to 24 °C, the German ones only below 15 °C. Four types of hybrids between German and American Pleupotus were obtained: i) The whole fruiting process is temperature sensitive as in German Pleurotus. ii) It proceeds at 4-24 °C as in American stocks, iii) Fruiting initiation is insensitive but sporophore development is sensitive to elevated temperatures, iv) Primordia formation and initial sporophore development depend on temperatures below 15 °C, but pileus expansion and spore discharge continue above 20 °. The involvement of separate genes for the single developmental steps and the use of temperature sensitivity for commercial varieties are discussed. One sporeless strain, "F42x11", with considerable fruiting bodies has been obtained. In intrastock di-mon-matings this character was dominant.