Distribution of Chromosomes into Discrete Groups in Colchicine-Induced C-Metaphases of Barley

Abstract

SUMMARY-Roots of barley were treated with 0.1-0.01% solutions of colchicine. After treatment with 0.1% or 0.05% colchicine, c-metaphases were seen in which chromosomes, each consisting of two sister-chromatids, were distributed into 2, and rarely into > 2, distinct groups. Each group of chromosomes gave rise to a restitution nucleus. The result of these distributive c-mitoses was the formation of binucleate or multinucleate cells. The pattern of distribution of the diploid complement of 14 chromosomes has been determined. It was not random: 7:7 distributions were relatively infrequent but 6:8 or 4:10 distributions occurred in high frequencies. This could result from the arrangement of chromosomes as they were released from the prophase nucleus but it appears also to involve movement of chromosomes, probably under the influence of cytoskeletal components. Bi-and multinucleate cells completed interphase and divided. In most of the binucleate cells, the two nuclei entered prophase in synchrony but a low percentage of asynchronous divisions were seen. The division of binucleate cells is related to the formation of homozygous cell lineages in colchicine treated plants.

Progress in Plant Polyploidization Based on Antimicrotubular Drugs

“…Generally, about 50% of the treated plants are responsive, but what is important, that three months can be added to the plant regeneration time to recover homozygous lines [7]. Additional drawbacks to using this approach include the regeneration of chimeras in many species [4][5], [8][9][10][11][12], the occurrence of aneuploids [13], abnormalities in plant development [14][15] and low seed yield. Chromosome losses or rearrangements and gene mutations caused by colchicine were found in flax, sunflower, barley and cotton [16].…”