Structural dynamics of cereal mitochondrial genomes as revealed by complete nucleotide sequencing of the wheat mitochondrial genome.
The application of a new gene-based strategy for sequencing the wheat mitochondrial genome shows its structure to be a 452 528 bp circular molecule, and provides nucleotide-level evidence of intra-molecular recombination. Single, reciprocal and double recombinant products, and the nucleotide sequences of the repeats that mediate their formation have been identified. The genome has 55 genes with exons, including 35 protein-coding, 3 rRNA and 17 tRNA genes. Nucleotide sequences of seven wheat genes have been determined here for the first time. Nine genes have an exon-intron structure. Gene amplification responsible for the production of multicopy mitochondrial genes, in general, is species-specific, suggesting the recent origin of these genes. About 16, 17, 15, 3.0 and 0.2% of wheat mitochondrial DNA (mtDNA) may be of genic (including introns), open reading frame, repetitive sequence, chloroplast and retro-element origin, respectively. The gene order of the wheat mitochondrial gene map shows little synteny to the rice and maize maps, indicative that thorough gene shuffling occurred during speciation. Almost all unique mtDNA sequences of wheat, as compared with rice and maize mtDNAs, are redundant DNA. Features of the gene-based strategy are discussed, and a mechanistic model of mitochondrial gene amplification is proposed.
Ogihara
Yasunari
Y
Faculty of Agriculture, Kyoto Prefecture University Sakyo-ku, Kyoto 606-8522, Japan.
Yamazaki
Yukiko
Y
Murai
Koji
K
Kanno
Akira
A
Terachi
Toru
T
Shiina
Takashi
T
Miyashita
Naohiko
N
Nasuda
Shuhei
S
Nakamura
Chiharu
C
Mori
Naoki
N
Takumi
Shigeo
S
Murata
Minoru
M
Futo
Satoshi
S
Tsunewaki
Koichiro
K
D001483:Base Sequence; D002874:Chromosome Mapping; D032621:DNA Shuffling; D018742:DNA, Chloroplast / Q000737:chemistry; D004272:DNA, Mitochondrial / Q000737:chemistry*; D019143:Evolution, Molecular; D018745:Genome, Plant; D008928:Mitochondria / Q000235:genetics*; D008969:Molecular Sequence Data; D011995:Recombination, Genetic; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D014908:Triticum / Q000235:genetics*
D018742:DNA, Chloroplast; D004272:DNA, Mitochondrial