Über das genetische Verhalten der SchmalblattformAngusta und über die Häufigkeit und Art spontaner Genom- und Chromosomenmutationen beiAutirrhinum majus L.

Abstract

1. After X-raying line 50 buds ofAntirrhinum majus a narrow-leaved mutant with aberrant genetic behaviour was found. This mutant (Angusta) is characterized by normal and narrow-leaf-types with different ratios in F1 after selfing or crossing with line 50 as paternal parent. The normal plants from these segregations remain normal in the next generations, while the Angusta-types are segregating into normal andAngusta in the following generations. A transmission of theAngusta-type through the pollen is impossible as shown by reciprocal crosses with line 50. 2. Trisomic inheritance or chromosome aberrations are not responsible for the genetic behaviour of Angusta. It is suggested that this behaviour is caused by a dominant factor which is responsible for the phenotype and inhibition or lethality of gones with theAngusta-allele (complete in the male, partial in the female-simultaneously). 3. Genome- and chromosome mutants in large populations of the homozygous line 50 were found with a frequency of 0,66%. The majority consisted of genome mutants (0,64%). 4. An analysis of meiosis in the plants used for crosses and selfings (Angusta, normal sister plants, plants of line 50) showed 1,87% cells with aberrant karyotypes in A I and 3,27% in T II. Most of these aberrations were caused by division disturbances (non-disjunction) leading to heteroploid gones.