黑麦特异重复序列pSc119.1在姊妹T1RS·1BL易位系中的变异

Variation of Rye-Specific repetitive DNA pSc119.1 among sister T1RS·1BL translocations

根据公布的黑麦特异重复序列pSc119.1设计特异引物,分别对两套姊妹T1RS·1BL易位系川农12(CN12)、川农17(CN17)、川农18(CN18)和96Ⅰ176-1、96Ⅰ176-3的基因组DNA进行扩增。从CN12、CN17、CN18的基因组中都能扩增出目的片段,在96Ⅰ176-1的基因组中,除目的片段外,还扩增出了一条非目的片段,但在96Ⅰ176-3的基因组中没有扩增出产物。Southernblot分析表明,pSc119.1序列并未从96Ⅰ176-3的基因组中消失。将CN12、CN17、CN18的目的片段回收克隆后,对每个片段各随机挑取10个克隆进行测序,pSc119.1序列在3个品种中都发生了变异,且在CN18中的变异程度最大。所测的序列多数与原序列达94%和95%的相似性,在这些序列中,碱基的改变具有一定的规律,即多数为转换,少数为颠换,且变异碱基和变异位置具有较高的一致性。远缘杂交后代的进化可能是一个持续过程,姊妹系内的株系之间某些性状存在差异,这些差异很可能与重复序列的变异有关,这为后生遗传效应机制的研究提供了有用的材料。

Specific primers were designed according to the rye-specific repetitive sequence pSc119.1 and were used for polymerase chain reaction （PCR） analysis using the genomic DNA of two sets of sister TIRS·1BL translocations, CN12, CN17, CN18, 96 Ⅰ176-1 and 96 Ⅰ 176-3 as templates. The results indicated that the target fragments were amplified from CN12, CN17, and CN18. A target and a non-target fragment were produced from 96 Ⅰ 176-1. However, no products were obtained from 96 Ⅰ 176-3. Southern blot analysis indicated that the elimination of pSc119.1 did not occur in line 96 Ⅰ 176-3. Three target fragments were cloned from CN12, CN17, and CN18 respectively through recovering. For each target fragment, ten clones were selected randomly for sequencing. Variation of the sequence pSc119.1 was observed in all of the three wheat lines and line CN18 had the most obvious variation. Most of the 30 sequences had 94% or 95% similarity with the sequence pSc119.1 published and the variation of bases of these sequences. Most variations of most bases arose from Wansition, and a few of them were transversion. Furthermore, there was great coherence among these changed bases in type and site. The evolution process of progenies of wide hybrids may be continuous. For each set of sister 1RS·1BL translocation, difference of some traits was observed among the wheat lines or cultivars. The difference was probably related to the variation of the repetitive DNA. This research provides some useful information for studying on mechanism of epigenetics.