Cytokinetic Aberrations in Impatiens sultani Mutants and Their Significance in Cytoplasmic Control of Pollen Wall Development

Abstract

A comparative study of the development of normal and aberrant microspores of two mutants of Impatiens sultani shows that initiation of cytokinesis is not restrained by aberrations in chromosomal cycle. Although cytokinetic cleavage begins simultaneously in normal and aberrant meiocytes, delay or blockage of the progression of furrowing occurs in atypical meiocytes resulting in lobed monads and dyads. Random cytoplasmic divisions in meiocytes with scattered chromosome groups of telophase II produce spores of various sizes enclosing 0-8 or more chromosomes. Despite these aberrations in the cleavage phase, all spores-even those with a single chromosome or no chromosome at all-develop pollen walls with identical exine pattern and chemical constitution, lending support to the suggested role of extrachromosomal factors in pollen wall development.