DESYNAPSIS IN PISUM SATIVUM INDUCED THROUGH GENE MUTATION

Abstract

A mutant of Pisum sativum showing various meiotic anomalies was isolated from X-irradiated material. These irregularities are due to a severe reduction of chiasmata frequency in pachytene resulting in univalent formation in the following meiotic stages. The action of this recessive gene shows considerable variations from PMC to PMC. As a consequence of this behaviour a large number of microspores is produced in each PMC having different chromosome numbers. The mutant is completely sterile in both sexes. Only very negligible differences were noted in the meiotic behaviour of this mutant in subsequent generations demonstrating that the action of gene ds82A is not influenced by extrinsic factors. It has been demonstrated that mutant 82A attains an extreme position in the scheme as compared with other desynaptic genotypes.