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GrainGenes Reference Report: GNM-44-517

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Reference	GNM-44-517
Title	The synaptic behaviour of the wild forms of Triticum turgidum and T-timopheevii
Journal	Genome
Year	2001
Volume	44
Pages	517-522
Author	Martinez M Naranjo T Cuadrado C Romero C
Abstract	Summary: Different wild allopolyploid species of Triticeae show extensive bivalent formation at zygotene while a considerable number of multivalents is present in cultivated polyploid wheats. To study the chromosome behaviour at early meiotic stages in wild forms of tetraploid wheats Triticum turgidum and T. timopheevii (2n = 4x = 28) we have analysed the synaptic pattern in fully traced spread nuclei at mid- and late zygotene and at pachytene of wild accessions of these species. The mean number of synaptonemal complex (SC) bivalents at mid-zygotene ranged from 12.22 to 13.14 among the accessions studied indicating a strong restriction of synapsis initiation to homologous chromosomes. The mean of bivalents increased at pachytene because of the transformation of multivalents into bivalents. Ring bivalents observed at metaphase I support that SC bivalents were formed by homologous chromosomes. The average values of SC bivalents at mid-zygotene in the wild forms are much higher than the average values observed in the cultivated tetraploid wheats but similar to that of a mutant line of T. turgidum with a duplication that includes Ph1, the major homoeologous pairing suppressor locus. These results suggest that the efficiency of the mechanism operating in the homologous recognition for synapsis is higher in wild wheat populations than in cultivated varieties. Apparently, a relatively detrimental modification of the pairing regulating genetic system accompanied the domestication of the wild wheat forms
Keyword	[ Hide all but 1 of 49 ] accessions aegilops allopolyploid bivalents canada chiasma formation chloroplast dna chromosome diploidisation domestication duplication genetic genetic diversity homologous chromosomes line locus mechanism metaphase metaphase-i modification mutant nuclear dna nuclei pachytene pairing pattern ph1 ph1 locus polyploid polyploid wheats population recognition restriction rflp analysis spread suppressor synapsis synaptonemal complex synaptonemal complex-formation tetraploid wheat timopheevii transformation triticeae triticum triticum timopheevii triticum turgidum turgidum wheat wild wheat

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