Abstract
BackgroundThe mitochondrial genomes of higher plants vary remarkably in size, structure and sequence content, as demonstrated by the accumulation and activity of repetitive DNA sequences. Incompatibility between mitochondrial genome and nuclear genome leads to non-functional male reproductive organs and results in cytoplasmic male sterility (CMS). CMS has been used to produce F1 hybrid seeds in a variety of plant species.ResultsHere we compared the mitochondrial genomes (mitogenomes) of Gossypium hirsutum sterile male lines CMS-2074A and CMS-2074S, as well as their restorer and maintainer lines. First, we noticed the mitogenome organization and sequences were conserved in these lines. Second, we discovered the mitogenomes of 2074A and 2074S underwent large-scale substitutions and rearrangements. Actually, there were five and six unique chimeric open reading frames (ORFs) in 2074A and 2074S, respectively, which were derived from the recombination between unique repetitive sequences and nearby functional genes. Third, we found out four chimeric ORFs that were differentially transcribed in sterile line (2074A) and fertile-restored line.ConclusionsThese four novel and recombinant ORFs are potential candidates that confer CMS character in 2074A. In addition, our observations suggest that CMS in cotton is associated with the accelerated rates of rearrangement, and that novel expression products are derived from recombinant ORFs.
Highlights
The mitochondrial genomes of higher plants vary remarkably in size, structure and sequence content, as demonstrated by the accumulation and activity of repetitive DNA sequences
The cytoplasmic male sterility (CMS) character is frequently used in crop breeding and commercial seed production to increase the yield of the crops such as rice, maize, rapeseed, and cotton [1,2,3,4,5]
CMS is maintained by the maintainer line which is similar to the CMS line in terms of the nuclear composition but is equipped with the male-fertile cytoplasm
Summary
The mitochondrial genomes of higher plants vary remarkably in size, structure and sequence content, as demonstrated by the accumulation and activity of repetitive DNA sequences. Incompatibility between mitochondrial genome and nuclear genome leads to non-functional male reproductive organs and results in cytoplasmic male sterility (CMS). Results: Here we compared the mitochondrial genomes (mitogenomes) of Gossypium hirsutum sterile male lines CMS-2074A and CMS-2074S, as well as their restorer and maintainer lines. We found out four chimeric ORFs that were differentially transcribed in sterile line (2074A) and fertile-restored line. Cytoplasmic male sterility (CMS), a phenomenon that the male reproductive structures fail to develop, is an important agronomical trait in higher plants. CMS is maintained by the maintainer line which is similar to the CMS line in terms of the nuclear composition but is equipped with the male-fertile cytoplasm. Plant mtDNA has a large number of repeats sequences and
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