title: Synaptic behaviour of the tetraploid wheat Triticum timopheevii.
abstract: Triticum timopheevii (2n=4x=A(t)A(t)GG) is an allotetraploid wheat which shows a diploid-like behaviour at metaphase-I. The synaptic process was analyzed in fully traced spread nuclei at mid-zygotene, late-zygotene and pachytene. The length and type of synaptonemal complexes, as well as the number of bivalent and multivalent associations, were determined in each nucleus. A high number of bivalents per nucleus was detected at all three stages. Nuclei at pachytene showed a lower frequency of multivalents than did zygotene nuclei, which suggests the existence of a pairing correction mechanism. At metaphase-I only homologous bivalents and, rarely, one pair of univalents were observed. Similarities between the diploidization mechanism of T. timopheevii and that of allohexaploid wheat, controlled by chromosome 5B, are discussed.
authors.affiliation: Departamento de Genética, Facultad de Ciencias Biológicas, Universidad Complutense, 28040, Madrid, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Martinez
authors.forename: T
authors.initials: T
authors.lastname: Naranjo
authors.forename: C
authors.initials: C
authors.lastname: Cuadrado
authors.forename: C
authors.initials: C
authors.lastname: Romero