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背景:胞质雄性不育(CMS)是由于线粒体基因组突变导致无功能性花粉产生的一种现象。对CMS和非CMS线粒体基因组的比较分析,揭示线粒体基因组间结构差异及因重组导致的广泛性重排具有重要意义。然而,在辣椒中与CMS相关的线粒体基因组结构及DNA重排机制仍不清楚。结果:获得了辣椒CMS FS4401(507 452 bp)和可育系Jeju(511 530 bp)线粒体完全基因组序列。并对辣椒、烟草线粒体基因组进行了比较分析,发现其均存在广泛的DNA重排和低保守性的非编码DNA区。FS4401和Jeju线粒体基因组比较发现,除了FS4401线粒体基因组中多了一个atp6(ψatp6-2)基因拷贝外,线粒体所有蛋白编码基因都一致。在基因组结构方面,发现两个线粒体基因组上的18个同线性序列区在基因组上存在重排,这些同线性序列区之间的序列总长度分别为30 380(FS4401)和17 847 bp(Jeju)。此前报道的CMS候选基因、orf507和ψatp6-2均位于FS4401最大特异序列片段的边界,在此区间大量的短序列片段聚集在一起,而Jeju中这些短序列表现为缺失或存在于不同的位点。连接序列片段的重复序列和重叠序列(由少数几个核苷酸组成)暗示同源重组导致的广泛性重排可能涉及到该区段的序列进化。本研究还利用其他植物种类的线粒体DNA序列进行分析,揭示CMS相关基因DNA区段的共同特征。结论:辣椒CMS和雄性可育系线粒体基因组大部分序列表现出一致性,但存在大量的基因组重排现象。辣椒CMS候选基因位于高度重排的CMS特定DNA区域的边界或重复序列附近。通过对其他物种CMS相关基因的特征分析,揭示出可能涉及到CMS相关基因进化的共同机制。
Background: Cytoplasmic male sterility (CMS) is a phenomenon caused by the mitochondrial genome mutation leading to non-functional pollen production. A comparative analysis of the CMS and non-CMS mitochondrial genomes reveals the structural differences between the mitochondrial genomes and the extensive rearrangements resulting from recombination. However, the CMS-related mitochondrial genome structure and DNA rearrangement mechanisms in pepper remain unclear. Results: The complete genome sequence of mitochondria was obtained from CMS FS4401 (507 452 bp) and fertile line Jeju (511 530 bp). The mitochondrial genomes of pepper and tobacco were comparatively analyzed and found that there existed extensive DNA rearrangements and low conservative non-coding DNA regions. Compared to the mitochondrial genome of FS4401 and Jeju, all of the mitochondrial protein-encoding genes were identical except for the more one copy of atp6 (ψatp6-2) in the FS4401 mitochondrial genome. In terms of the genomic structure, 18 homozygous regions of the two mitochondrial genomes were found to be rearranged in the genome. The total length of sequences between these homologous regions was 30 380 (FS4401) and 17 847 bp (Jeju) . Previously reported CMS candidate genes, orf507 and ψatp6-2, were located at the boundaries of the FS4401, the largest specific sequence fragment in which a large number of short sequence fragments clustered together and these short sequences in Jeju were deleted or present at different sites . The repetitive and overlapping sequences (consisting of a few nucleotides) of linked sequence fragments suggest that extensive rearrangements resulting from homologous recombination may be involved in the sequence evolution of the segment. In this study, mitochondrial DNA sequences of other plant species were also analyzed to reveal the common features of DNA segments of CMS-related genes. CONCLUSION: Most sequences of the mitochondrial genome of pepper CMS and male fertile lines show consistency, but there are a large number of genomic rearrangements. Pepper CMS candidate genes are located near the boundaries or repetitive sequences of highly rearranged CMS-specific DNA regions. By analyzing the characteristics of CMS-related genes in other species, a common mechanism that may involve the evolution of CMS-related genes was revealed.