Abstract: Cytoplasmic male sterility (CMS) can significantly reduce the labor costs associated with artificial emasculation. In this study,the sterile alfalfa line MSGN-1A and its maintainer line MSGN-1B were utilized as experimental materials. The second-generation Illumina Hiseq sequencing technology,combined with third-generation PacBio sequencing technology and third-generation Naopore sequencing was employed to assist filling the gap. The mitochondrial genomes of the two materials were sequenced and assembled. Subsequently,a comparison and analysis of the mitochondrial genome structure and gene differences between the sterile line and the maintainer line were conducted.The results revealed that the mitochondrial genome sizes of MSGN-1A and MSGN-1B were 297 940 bp and 310 534 bp,respectively. Additionally,31 protein-coding genes,18 tRNA genes,and 3 rRNA genes were annotated in both materials. A significant number of SNPs and InDels were identified in both sterile lines and maintainers,which lead to the changes in the coding products of certain protein-coding genes. Furthermore,67 coded Open Reading Frames (ORFs) were predicted for MSGN-1A,while 71 ORFs were predicted for MSGN-1B. Among these ORFs,20 were specific to sterility lines with eight containing transmembrane domains.Finally,four protein-coding genes (atp8,nad4,rps3,and ccmFn) along with two ORFs (orf145a and orf135b) were identified as potential candidates related to cytoplasmic male sterility in alfalfa.

Key words: Alfalfa (Medicago sativa L.), Cytoplasmic male sterility, Mitochondrial genome, Differential genes

摘要： 细胞质雄性不育(Cytoplasmic male sterility，CMS)，它可以极大地减少人工去雄所带来的人工成本。本试验以紫花苜蓿(Medicago sativa L.)不育系MSGN-1A及其保持系MSGN-1B为试验材料，采用二代Illumina Hiseq测序技术结合三代PacBio测序技术，并以三代Naopore测序作为辅助进行gap补平，对2份材料的线粒体基因组测序后进行组装，并比较分析不育系和保持系的线粒体基因组结构和基因差异。结果显示紫花苜蓿MSGN-1A和MSGN-1B线粒体基因组大小分别为297 940 bp和310 534 bp，两份材料均注释到蛋白编码基因31个，tRNA基因分别为18个和17个，均注释到3个rRNA基因。不育系和保持系对比发现存在大量的SNPs和InDels，导致部分蛋白编码基因的编码产物发生变化。预测编码开放阅读框(Open reading frame，ORFs)分别为67个和71个，预测到不育系特有的ORFs为20个，其中8个含有跨膜结构域。最终筛选出atp8，nad4，rps3，ccmFn四个蛋白编码基因和orf145a，orf135b两个ORFs，可能与紫花苜蓿细胞质雄性不育有关。

关键词: 紫花苜蓿, 细胞质雄性不育, 线粒体基因组, 差异基因