Uncontrolled growth associated with novel somatic recombination in the fungusSchizophyllum

摘要

AbstractIn the bracket mushroom,Schizophyllum commune, a recessive genetic alteration,mnd, causes abnormally hyperplastic three‐dimensional mounds of hyphae to rise from the surface of both haploid and dikaryotic mycelia.mnd, although not a genetic block in the fruiting body developmental pathway, is at least partially epistatic to fruiting. Within dikaryons containing both mutant and wild‐type nuclei, mnd + mnd+, a nonreciprocal somatic recombination event can lead to stable conversion of themnd+region of the wild‐type nucleus tomnd.This transformation to the homoallelic mnd+mnd condition involves no genomic areas other than themndregion and permanently prevents any further fruiting. Studies relating to the recombination mechanism have ruled out a diploid intermediate state and other concomitants of orthodox somatic recombination, as well as whole chromosome transfer. Instead, a novel form of internuclear genetic transfer is postulated whereby a nearby locus, mob+, controls the mobilization of themndchromosomal region alone from one nucleus to the other within the binucleate cells of dikaryotic my