Experimental Studies on the Morel. I. Heterokaryon Formation Between Monoascosporous Strains of Morchella

Three lines of evidence are reported for heterokaryon formation in Morchella esculenta and related species. Cultural studies demonstrated a genetic basis for different types of interactions between mycelia from sister and non-sister spores. Cytological studies of the mycelial interaction between non-sister monoascosporous isolates demonstrated nuclear pairing in presumptive heterokaryons. Two different mutations isolated in this study were used to show genetic complementation in these heterokaryons.