Genetic Evidence for Nuclear Migration in Basidiomycetes

Abstract

N various fungi genetically marked nuclei implanted in a mycelium can be Irecovered centimeters from the point of implantation after an interval of hours or days. The transport of such nuclei (or their mitotic progeny) could occur by the dispersal of spores, by the intrusive growth of new hyphae, by the migration of whole nuclei through pre-existing hyphae, or by other means. In fact, such transport may occur by a variety of mechanisms in the same fungus.Although the idea of nuclear migration in fungi has become widespread, PAPAZIAN (1958, pp. 44-45) has questioned the absolute validity of the evidence for migration in Basidiomycetes, and even in a recent article about migration, SWIEZYNSKI (1961) evaluates the evidence with the guarded comment that "The alternative hypothesis . . . is difficult to accept for various reasons.'' The original report of nuclear translocation by migration in fungi (BULLER 1931) involved Coprinus Zagopus (Basidiomycetes) and was based upon: ( 1 ) kinetic data indicating the rate of nuclear migration is faster than the rate of hyphal-tip g r o~h (p. 217), and (2) genetic data involving the detection and recovery of migrating nuclei from preexisting, partially isolated hyphae (pp. 234-241). More recent studies of nuclear migration, including those of FULTON ( 1950FULTON ( , 1951 , KIMURA