A HIGH FREQUENCY OF HETEROZYGOUS DIPLOIDS AND SOMATIC RECOMBINATION INDUCED IN IMPERFECTI FUNGI BY ULTRA-VIOLET LIGHT
1957 Volume 3 Issue 1 Pages 1-11
Details
1957 Volume 3 Issue 1 Pages 1-11
1. The presence of parasexual life cycle in Aspergillus oryzae was identified again.
2. The frequency of diploidization was increased from less than 5x10-4 to a few percent of the survivors by irradiating heterocaryotic conidia with ultraviolet light. The value is sufficiently high to utilize the process for breeding purpose.
3. Comparing the survival curves of two haploids and the heterocaryon with that of the heterozygous diploid, the diploid conidia were considered to have no selective advantage in survival during the irradiation.
4. As the first order somatic segregants of a diploid, ten out of the twelve possible phenotypes which were expected to come from the combination of white leucineless and yellow lysineless were really recovered. Some of them were proved to be still diploids.
5. A few supposed triploid and tetraploid strains were produced from the cross between a haploid and a diploid and between two diploids.
6. Ultraviolet light was demonstrated to be effective upon the segregation of a diploid as well as on the formation of a diploid. The effect on the former depends on the strain.
7. An attempt which has been carried out to improve industrial strains through this process will be published later.
