The behavior of isochromosomes and telocentrics in wheat.

Abstract

Genetic tests with chromosome IX of common wheat showed 13.3% formation of isochromosomes from telocentrics as against 7.0% for the same long arm of normal IX, and 7.0% formation of telocentrics from each arm of iso-IX instead of 10.8% from the same arm of normal IX. The differences are not significant statistically. No differences in frequency of formation of isochromosomes were found among 16 independently produced telocentrics for the long arm of chromosome IX. Somatic loss of both telocentrics and isochromosomes for chromosome IX and other wheat chromosomes has been observed, with loss of the telo being somewhat more frequent. A telocentric gave rise, to an isochromosome somatically. and isochromosomes added a telocentric. Two complex aberrations involving loss and duplication of parts of arms were observed, one of a telo and one of an iso; but these aberrations probably occurred at meiosis.