Sib mating in trifolium pratense part 2 cyto genetics of eu ploids aneu ploids and poly ploids
Genetica Polonica 17(4): 497-516
While cytogenetically analyzing plants of T. pratense from sib-mating it was found that in some individuals division proceeds without any irregularities; in other plants there occur certain, somtimes far-going deviations from the typical course of meiosis and sporogenesis. Particularly strong abnormalities characterized male-sterile plants isolated from the population. Such individuals, in addition to other features, displayed partial and even complete asynapsis and desynapsis during meiosis. Analyses of anther development in plants with withering anthers, in contrast to male-sterile forms, showed no successive use of tapetum cells. Isolated aneuploid plants (2n = 16) were characterized by great irregularities in meiosis and by the production of a large percentage of nonfunctional spores. Among plants with indehiscent anthers there were some which in the process of microsporogenesis formed polyploid microspores with the chromosome number from 28-56. Spontaneous polyploids (triploids 2n = 21; heksaploid 2n =42) were characterized by great abnormalities in the course of meiosis and sporogenesis. Sterility, as shown by analyses of the course of meiosis and sporogenesis and by histological studies on developing anthers was caused by asynapsis and desynapsis in some plants and by degeneration of sporogenous cells and anther withering in others.