Interspecific Hybridization between Aspergillus nidulans and Aspergillus rugulosus by Fusion of Somatic Protoplasts

Abstract

~~~ ~Interspecific heterokaryons have been produced between auxotrophic mutants of Aspergillus nidulms and Aspergillus rugulosus by polyethylene glycol induced fusion of somatic protoplasts. The heterokaryons grew very slowly producing colonies of irregular shape and, on complete medium, the parental strains were readily segregated. However, during longterm cultivation on minimal medium many of the heterokaryons gave rise to vigorously growing sectors characterized by the secretion of a brown pigment and by their stability when subcultured on complete medium. Protoplasts isolated from the heterokaryons gave rise to the same new colony type when regenerated on minimal medium, and to the new colony type plus the parental types on complete medium. The new colony type was assumed to be an interspecific 'hybrid' and showed normal vegetative morphology, regular colony shape and size but produced few conidia. Conidia formed early in the development of the 'hybrid' gave rise to 'hybrid' colonies. Various sizes of conidia were observed; the largest were uninucleate and the smallest were enucleate. Comparisons of conidial size, numbers of nuclei in cells and DNA content per nucleus for 'hybrid' and parental strains indicated that the 'hybrid' was diploid. Conidia from older cultures of the 'hybrid' were heterogeneous with 'hybrid ', parental and recombinant colony types developing on germination. Cultivation of the 'hybrid' in the presence of benomyl gave segregation of parental and recombinant sectors.

Piriformospora indica: An Axenically Culturable Mycorrhiza-Like Endosymbiotic Fungus

“…The removal of hyphal wall at protoplast formation may permit more extensive interaction between them (Kevei and Peberdy 1977;Baltz 1978). Protoplast fusion overcomes the problem of low recombination frequencies typically attained with natural systems (Hopwood 1981) and creating novel strains that display enhanced biotechnological potential (Kavanagh and Whittaker 1996).…”

Breeding by Protoplast Fusion of Koji Mold, Aspergillus sojae

“…Protoplast fusion has also been investigated in Aspergillus nidulans, 32,33) this protoplast fusion technique being used not only for the breeding a certain desired strain but for analyzing genetic. detects of the organism.…”

Further characterization of the role of the mitochondrial high-mobility group box protein in the intracellular redox environment of Aspergillus nidulans

“…shaking. The protoplasts were prepared from mycelia grown over cellophane (Ferenczy et al, 1975;Kevei & Peberdy, 1977) using a 4 % (w/v) solution of Glucanex (Novozymes) in 0.7 M KCl. Oxygen consumption rates were measured with a Respire 1 Clark-type oxygen electrode (Hansatech).…”