A Polyhaploid Clone of Bromus inermis Leyss with Chromosome Fragments
1977 年 42 巻 3-4 号 p. 547-551
詳細
1977 年 42 巻 3-4 号 p. 547-551
An additional fragment frequently appeared in the root tip cells from a polyhaploid clone of smooth bromegrass (Bromus inermis Leyss). Occasionally, two or three fragments could be observed.
Comparison of karyotypes between ramets with and without a fragment revealed that the fragment may have originated from the satellite which was detached from one of the SAT-chromosomes. The division of the SAT-chromosomes was considerably delayed at anaphase in the unpretreated root tip from the ramet with the fragment. In most cases the lagged satellite eventually divided and incorporated into the daughter nuclei. However, in many divisions the separation of the daughter satellites was so much delayed that, as a result of the poleward movement, a break occurred between the daughter satellite and one of the parent chromosomes. The detached daughter satellite later became a fragment. Misdivision, lagging or nondisjunction of the daughter fragment could explain the different number of fragments in subsequent generations of cell divisions.
