序列消除与异源多倍体植物基因组的进化

Sequence Elimination and the Genomic Evolution of Allopolyploid Plants

经杂交后多倍化形成的异源多倍体植物,被认为在其形成的早期阶段经历了DNA序列消除过程。发生消除的序列既涉及到高拷贝的序列也有低拷贝的序列,而且大多数情况下倾向于消除来自其中一个亲本的序列。序列消除的模式因基因组组成和物种的不同而有差异,并且可能受到细胞质的影响。尽管序列消除的分子机制还不是很清楚,但很多证据已表明非同源染色体之间的互作不是主要的原因。目前认为,序列消除增加了非同源染色体之间的差异,为多倍化后在减数分裂过程中快速恢复二倍化的染色体配对模式提供了物质基础,这样更有利于多倍体在自然界快速稳定。

Allopolyploids,resulted from combination of two or more differentiated genomes,have undergone DNA sequence elimination in the early stage after the formation of allopolyploids.The sequences eliminated,involving not only high-copy but also low-copy DNA sequences,mostly are from one of the parental genomes.The modes of sequence elimination are different among both various genomic constituents and species,perhaps affected by the cytoplasm.Although the mechanisms of molecular interactions that underlie sequence elimination are not very clear at present,many investigations have indicated that inter-homoeologous chromosomal recombination is not the main impact factor.It has been speculating that sequence elimination has increased the divergence between homoeologous chromosomes,provided a physical basis for rapid restoration of diploid-like chromosome paring pattern in meiosis following polyploidization,and thereby possibly demonstrated polyploidy-facilitated adaptation.