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多倍体小麦及其二倍体祖先物种的基因组DNA经一对同位酶(Hpa Ⅱ/MspⅠ)消化后,与21个不同类型的低拷贝DNA序列进行Southern杂交。结果发现,多倍体小麦实现物种形成后产生了广泛的胞嘧啶甲基化变异。用同样的21种DNA序列为探针与1个人工合成的六倍体小麦及其亲本的Southern杂交结果表明,甲基化变异已存在于该人工小麦的较早期自交世代(S_5,S_6和S_7)。而且,在3个自交世代每代随机选取的3个单株之间的限制性酶切片段长度多态(RFLP)谱带均表现为高度一致;这暗示甲基化变异可能发生得更早,或者,甲基化变异具有非随机性。变化后的RFLP谱带在3个自交世代间表现为稳定遗传。甲基化变异虽在整个基因组范围内发生,但可能具有序列特异性。对这种迅速发生的甲基化变异与异源多倍体基因组进化的两个重要属性即遗传二倍化和基因分化之间的可能关系进行了讨论。
Genomic DNA from polyploid wheat and its diploid ancestral species was digested with a pair of homologous enzymes (HpaII / MspI) and Southern blotted with 21 different types of low-copy DNA sequences. The results showed that polyploid wheat produced a wide range of cytosine methylation variation after species formation. The results of Southern hybridization using the same 21 DNA sequences as probe and a synthetic hexaploid wheat and their parents showed that methylation variation existed in the early selfing generations (S_5, S_6 and S_7). Furthermore, the RFLP bands of 3 restriction fragments randomly selected from each of three selfing generations for each generation were highly consistent; suggesting that methylation variation may occur earlier , Or, methylation mutations are non-random. The changed RFLP bands showed stable inheritance among the three selfing generations. Methylation variants, although occurring throughout the genome, may have sequence specificity. The possible relationship between this rapidly occurring methylation mutation and two important properties of allopolyploid genome evolution, genetic diploidization and gene differentiation, is discussed.