Relationship between the levels of wheat-rye metaphase I chromosomal pairing and recombination revealed by GISH.
The metaphase I and anaphase I stages of meiosis of wheat x rye hybrids carrying the ph1b mutation were analyzed by genomic in situ hybridization. This technique allows distinction between three different types of wheat-rye associations in metaphase I configurations as well as detection of wheat-rye recombinant chromosomes in anaphase I cells. The frequency of associations between wheat and rye chromosomes greatly exceeded the level of wheat-rye recombination found in the three hybrids examined. Extremely distal associations, which account for about 50% of the total wheat-rye metaphase I chromosomal pairing, can explain such a discrepancy between metaphase I and anaphase I data. It is further discussed whether these associations reflect very distally located chiasmata or nonchiasmatic pairing. The sizes of the segments exchanged in wheat-rye recombinant chromosomes provide cytological evidence that wheat-rye recombination is restricted to the distal chromosomal regions.
Benavente
E
E
Unidad de Genética, E.T.S.I. Agrónomos, Universidad Politécnica de Madrid, Ciudad Universitaria, E-28040 Madrid, Spain.
Fernández-Calvín
B
B
Orellana
J
J
D000705:Anaphase / Q000235:genetics; D002875:Chromosomes / Q000502:physiology*; D017343:Genes, Plant; D006822:Hybrid Cells / Q000648:ultrastructure; D017403:In Situ Hybridization / Q000379:methods*; D008677:Metaphase / Q000235:genetics; D008856:Microscopy, Fluorescence; D011995:Recombination, Genetic; D012434:Secale / Q000166:cytology / Q000235:genetics*; D014908:Triticum / Q000166:cytology / Q000235:genetics*