Genetic analysis of further suppressor genes in Antirrhinum majus L

Summary Abnormal segregation of the recessive character squamosa in the progeny of an X-rayed pure line is due to the action of a specific suppressor and besides that a lethal factor, both linked to the squa-locus, the order being approximately squa-20%-let-24%-sup_squa. As a consequence in X₃ and X₄squamosa-individuals sometimes produce about 25% normal plants, if the lethal is absent, and about 31%, if it is present, while normal individuals may produce about 25% squamosa or 31% respectively. By crossing over 9 genotypes may arise, each giving a specific segregation-ratio.As the original order of the genes in X₁ was established to have been Squa+s/squa let S, only squa may have originated by X-radiation, while the suppressor sup_squa is assumed to have been present in the untreated egg-cell. A combination of mutant genes closely linked to a lethal and a suppressor is liable to detected for some time. This model gives a good heterozygeous condition without being detected for some time. This model gives a good explantation for the specific mutation spectra formerly established in different sub-lines of Antirrhinum majus. As Sippe 50 containes a series of suppressors and mutator genes as well, some attention should be directed to its RNS-metabolism.