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United States Department of Agriculture

Agricultural Research Service

Research Project: AN INTEGRATED DATABASE AND BIOINFORMATICS RESOURCE FOR SMALL GRAINS

Location: Genomics and Gene Discovery

Title: Accelerated evolution of the mitochondrial genome in an alloplasmic line of durum wheat

Authors
item Noyszewski, A -
item Ghavami, F -
item Al-Nimer, L -
item Soltani, A -
item Gu, Yong
item Huo, N -
item Meinhardt, S -
item Kianian, P -
item Kianian, S -

Submitted to: Biomed Central (BMC) Genomics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 15, 2014
Publication Date: January 25, 2014
Repository URL: http://www.biomedcentral.com/1471-2164/15/67
Citation: Noyszewski, A., Ghavami, F., Al-Nimer, L., Soltani, A., Gu, Y.Q., Huo, N., Meinhardt, S., Kianian, P., Kianian, S. 2014. Accelerated evolution of the mitochondrial genome in an alloplasmic line of durum wheat. Biomed Central (BMC) Genomics. 15:67.

Interpretive Summary: Wheat is not only an important crop, but also an excellent plant species for nuclear mitochondrial interaction studies. Mitochondrion is a crucial component of every eukaryotic cell and provides indispensable functions including i) cell energy supply ii) synthesis of essential molecules such as phospholipids and heme, and iii) mediating multiple cellular signaling pathways including stress response, apoptosis and aging. It is widely accepted that mitochondria and chloroplasts descended from free-living bacterial ancestors that were acquisitioned into eukaryotic cells. Following their acquisition, most of the genes in these organelles were either lost or transferred to the nucleus. To study the evolution of mitochondrial genomes, we sequenced several mitochondrial genomes from different wheat species and performed detailed sequence comparison of genes encoded in the mitochondrial genomes. Our study allowed us understand the patterns of sequence changes in mitochondrial genes. The research result enhanced our understanding of the evolution of mitochondrial genomes in wheat species.

Technical Abstract: Wheat is not only an important crop but also an excellent plant species for nuclear mitochondrial interaction studies. To investigate the level of sequence changes introduced into the mitochondrial genome under the alloplasmic conditions, three mitochondrial genomes of Triticum-Aegilops species were sequenced. The mitochondrial genomes of T. turgidum was 451,925bp, with high structure and nucleotide identity to the previously characterized T. aestivum cv. Chinese Spring mitochondrial genome. The assembled mitochondrial genomes of (lo) durum and Ae. longissima were about 432,606bp and 399,074bp in size, respectively. The high sequence coverage of 61-133 folds for all three genomes allowed for analysis of heteroplasmy within each chondriome. The mitochondrial genome structure in alloplasmic line was not only genetically distant from T. turgidum but also different from its maternal parent Ae. longissima. The alloplasmic durum and Ae. longissima carry the same versions of atp6, nad6, rps19-p, cob and cox2-2 which are different from T. turgidum. Next generation sequencing technologies are powerful tools for studying heteroplasmy and stoichiometric changes in chondriome of plants. Several heteroplasmic regions were observed within genes and intergenic regions of mitochondrial genome in all three lines. The number of rearrangements and nucleotide changes in the mitochondrial genome of the alloplasmic line was significant considering the high sequence conservation between T. turgidum and T. aestivum that have diverged 10,000 years of evolution. We showed that the changes occurred in the genes was not only resulted from paternal leakage and was also caused by other active mechanisms of heteroplasmy such as recombination and mutation. The newly formed ORFs, differences in gene sequences and copy numbers, heteroplasmy, and substoichiometric changes show the potential of alloplasmic condition to accelerate the evolution toward forming new mitochondrial genomes.

Last Modified: 9/23/2014
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