生物
多倍体
倍性
遗传学
基因组
染色体
山羊草
同源染色体
重复序列
DNA
基因
作者
B Liu,Maximiliano Rodrigo Vega,G. M. Segal,Shahal Abbo,Marianna Rodova,Moshe Feldman
出处
期刊:Genome
[NRC Research Press]
日期:1998-04-01
卷期号:41 (2): 272-277
被引量:130
摘要
We recently reported that allopolyploid formation in wheat was accompanied by rapid nonrandom elimination of specific low-copy, noncoding DNA sequences. These sequences occur in all diploid progenitors but are chromosome- or genome-specific at the polyploid level. To further investigate this phenomenon, we studied nine of these sequences, six chromosome-specific sequences and three genome-specific sequences, all isolated from common wheat. The various sequences were hybridized to DNA derived from nine newly synthesized amphiploids at different ploidy levels and to DNA from their parental lines. Although sequences homologous to the probes occur in all parental lines, a nonrandom loss of hybridization fragments was found at a high frequency in all amphiploids studied. In addition, a "loss/gain" of a hybridization fragment(s) was noticed in some of the amphiploids at lower frequency. Neither the type nor the frequency of changes was affected by intergenomic recombination or DNA methylation. It is suggested that rapid genomic changes culminated in a "programmed" pattern of elimination and (or) modification of specific low-copy DNA sequences following allopolyploidization. These events augmented the differentiation of homoeologous chromosomes, thus providing the physical basis for the diploid-like cytological behavior of polyploid wheat.Key words: wheat, allopolyploidy, genome evolution, chromosome- or genome-specific sequences, sequence elimination, homoeologous chromosome differentiation.
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