title: Comparative analysis of mitochondrial genomes between a wheat K-type cytoplasmic male sterility (CMS) line and its maintainer line.
abstract: BACKGROUND
  Plant mitochondria, semiautonomous organelles that function as manufacturers of cellular ATP, have their own genome that has a slow rate of evolution and rapid rearrangement. Cytoplasmic male sterility (CMS), a common phenotype in higher plants, is closely associated with rearrangements in mitochondrial DNA (mtDNA), and is widely used to produce F1 hybrid seeds in a variety of valuable crop species. Novel chimeric genes deduced from mtDNA rearrangements causing CMS have been identified in several plants, such as rice, sunflower, pepper, and rapeseed, but there are very few reports about mtDNA rearrangements in wheat. In the present work, we describe the mitochondrial genome of a wheat K-type CMS line and compare it with its maintainer line.
  
  
  RESULTS
  The complete mtDNA sequence of a wheat K-type (with cytoplasm of Aegilops kotschyi) CMS line, Ks3, was assembled into a master circle (MC) molecule of 647,559 bp and found to harbor 34 known protein-coding genes, three rRNAs (18 S, 26 S, and 5 S rRNAs), and 16 different tRNAs. Compared to our previously published sequence of a K-type maintainer line, Km3, we detected Ks3-specific mtDNA (> 100 bp, 11.38%) and repeats (> 100 bp, 29 units) as well as genes that are unique to each line: rpl5 was missing in Ks3 and trnH was absent from Km3. We also defined 32 single nucleotide polymorphisms (SNPs) in 13 protein-coding, albeit functionally irrelevant, genes, and predicted 22 unique ORFs in Ks3, representing potential candidates for K-type CMS. All these sequence variations are candidates for involvement in CMS. A comparative analysis of the mtDNA of several angiosperms, including those from Ks3, Km3, rice, maize, Arabidopsis thaliana, and rapeseed, showed that non-coding sequences of higher plants had mostly divergent multiple reorganizations during the mtDNA evolution of higher plants.
  
  
  CONCLUSIONS
  The complete mitochondrial genome of the wheat K-type CMS line Ks3 is very different from that of its maintainer line Km3, especially in non-coding sequences. Sequence rearrangement has produced novel chimeric ORFs, which may be candidate genes for CMS. Comparative analysis of several angiosperm mtDNAs indicated that non-coding sequences are the most frequently reorganized during mtDNA evolution in higher plants.
authors: The State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China.
authors: Huitao
authors: H
authors: Liu
authors: Peng
authors: P
authors: Cui
authors: Kehui
authors: K
authors: Zhan
authors: Qiang
authors: Q
authors: Lin
authors: Guoyin
authors: G
authors: Zhuo
authors: Xiaoli
authors: X
authors: Guo
authors: Feng
authors: F
authors: Ding
authors: Wenlong
authors: W
authors: Yang
authors: Dongcheng
authors: D
authors: Liu
authors: Songnian
authors: S
authors: Hu
authors: Jun
authors: J
authors: Yu
authors: Aimin
authors: A
authors: Zhang
mesh_terms: D055028:Comparative Genomic Hybridization; D004251:DNA Transposable Elements; D018744:DNA, Plant / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D054629:Genome, Mitochondrial; D018745:Genome, Plant; D015698:Genomic Library; D016366:Open Reading Frames; D020161:Physical Chromosome Mapping; D051479:Plant Infertility / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D014908:Triticum / Q000235:genetics*
chemical_list: D004251:DNA Transposable Elements; D018744:DNA, Plant