ABSTRACT
Spore killers (Sk) in fungi are chromosomal elements that distort allele ratios of Sk and Sk-linked genes. They are expressed postmeiotically, causing the death of ascospores that do not receive the killer element. Ascospore death occurs when one parent carries the killer element (SkK) and the other parent carries the sensitive counterpart (SkS). The beststudied examples are found in the filamentous ascomycetes Neurospora and Podospora. Turner and Perkins [1] first showed that ascospore death in certain crosses of Neurospora sitophila and N. intermedia resulted from the action of spore killers. In crosses of killer×sensitive, each ascus produces four large, black, viable ascospores (SkK) and four small, hyaline, in viable, ascospores (SkS). Earlier, Padieu and Bernet [2] had described ascospore death in crosses between Podospora strains and had attributed it to two independently segregating ascospore abortion factors. In fact, the Podospora abortion factors showed all the characteristics of spore killers [3]. Additional spore killers have recently been found in wild P. anserina populations [4]. They were also found in Gibberella fujikuroi (Fusarium moniliforme) [5] and Cochliobolus heterostrophus [6].
