Behaviour of DNA-induced inositol-independent transformants of Neurospora crassa in sexual crosses

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Abstract
Treatment of inositolless (inl) strains of Neurospora crassa with DNA from the wild type (allo-DNA) gives rise to inositol-independent (inl+) colonies. Some of these DNA-induced inl+ strains (transformants) are sterile in sexual crosses on minimal medium that selects for the maintaining of the inl+ character. The same inl+ transformants, when crossed with an inl standard strain, are fertile on complete (inositol-containing) medium. There are, however, an increased number of unusual non-Mendelian tetrads (24%) among the progeny. The inl+ and inl progeny from these complete non-Mendelian tetrads were further examined for the inheritance of the inl+ trait. Several inl+ progeny of these tetrads segregate inl conidia if growing on inositol-containing medium. The number of inl+ conidia in certain inl+ cultures decreases quickly under non-selective conditions. In transformants carrying mutant markers in linkage groups III, IV and VI non-Mendelian segregation of these traits can also be detected. The mechanism of the development of sterility and of the aberrant segregation is discussed.