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GrainGenes Reference Report: CHR-110-371

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Reference	CHR-110-371
Title	Analysis of karyotypic stability of homoeologous-pairing (ph) mutants in allopolyploid wheats
Journal	Chromosoma
Year	2001
Volume	110
Pages	371-377
Author	Sanchez-Moran E Benavente E Orellana J
Abstract	Summary: Karyotypic analysis of wheat lines with different genotypes for the homoeologous-pairing loci Ph1 and Ph2 was carried out by means of a genomic in situ hybridization method that allowed unequivocal identification of the A, B and D genomes. Chromosomal rearrangements mainly affecting the A and D genomes were found in all plants of allohexaploid wheat (AABBDD) lacking Ph1 activity. The frequency of intergenomic exchanges per plant in ph1b mutant and nulli-5B lines was 4.31 and 3.40, respectively. In addition, an unbalanced genomic constitution was found in a few plants, some even showing a euploid chromosomal number. By contrast, rearranged karyotypes were detected neither in the ph1 mutant line (ph1c) of allotetraploid wheat (AABB) nor in the allohexaploid wheat lines lacking Ph2 activity, namely ph2b mutant and nulli-3D lines. These results were compared with the chromosomal pairing behaviour displayed by mutant lines ph1c, ph1b and ph2b at first meiotic metaphase. Despite the finding of standard, non-rearranged karyotypes in the ph1c tetraploid mutant, the frequency of A-B homoeologous metaphase I association was similar to that observed in the ph1b hexaploid mutant. The results presented clearly demonstrate that inactivity of the Ph1 locus induces karyotypic instability in wheat. Intergenomic exchanges have probably been accumulating since the original ph1 mutant and aneuploid lines were obtained, which should be taken into account when it is planned to use these lines for basic research on Ph1 function or in applied wheat breeding programmes
Keyword	[ Hide all but 1 of 49 ] addition aegilops allohexaploid wheat allopolyploid aneuploid aneuploid lines b genome breeding breeding programme chromosomal rearrangements chromosome d genome exchange frequencies function genome genomes genomic constitution genomic in situ hybridization genotype hexaploid hybrid hybridization in situ in situ hybridization instability karyotype karyotypic analysis loci locus mechanism metaphase metaphase-i method mutant nor pairing ph ph1 ph1 locus rearrangements recognition rye situ hybridization speltoides stability tetraploid wheat wheat breeding

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