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Cell fusion: A possible mechanism for the origin of polyploidy

1995; Elsevier BV; Volume: 61; Issue: 2 Linguagem: Africâner

10.1016/s0254-6299(15)30480-4

1727-9321

J. J. Spies, S. M. C. Van Wyk,

Plant tissue culture and regeneration

Different ploidy levels in meiocytes within the same anther are occasionally observed. These result from cell fusion during microsporogenesis. Fusion usually occurs during early prophase (leptonema to zygonema) and may include many cells (in this study up to 17 cells were observed). The polynucleate fused cell usually forms a single spindle and meiosis appears normal. The end result of meiosis is polyhaploid gametes. Fused cells, and the gametes developing from them, are much larger than the normal (unfused) cells. This phenomenon occurred in one in a hundred to one in a thousand meiocytes and was observed in unrelated taxa, e.g. Poaceae (19 genera representing all subfamilies except Bambusoideae) and Solanaceae (Lycium). Verskillende ploïdievlakke word soms in ’n enkele helmknop waargeneern. Dit is die resultaat van selfusie tydens mikrosporogenese. Selfusie vind plaas tydens vroeë profase (leptoteen tot sigoteen) en baie selle kan betrokke wees (tot 17 selle is tydens hierdie studie waargeneem). Die veelkernige fusiesel vorm gewoonlik een spoel en meiose vertoon normaal. Die eindresultaat van meiose is polihaploïede gamete. Fusieselle en die gamete wat uit hulle ontwikkel, is baie groter as die normale onversmelte selle. Hierdie verskynsel kom voor by een uit ’n honderd tot een uit ’n duisend meiosiete en is by onverwante taksa waargeneem, bv, Poaceae (by 19 genera wat al die subfamilies met uitsondering van die Bambusoideae verteenwoordig) en Solanaceae (Lycium).