plant genome
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Rescooped by Faith Wu from Plant Genomics
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PLOS Biology: Rapid Evolution of Enormous, Multichromosomal Genomes in Flowering Plant Mitochondria with Exceptionally High Mutation Rates

PLOS Biology: Rapid Evolution of Enormous, Multichromosomal Genomes in Flowering Plant Mitochondria with Exceptionally High Mutation Rates | plant genome | Scoop.it

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Genome size and complexity vary tremendously among eukaryotic species and their organelles. Comparisons across deeply divergent eukaryotic lineages have suggested that variation in mutation rates may explain this diversity, with increased mutational burdens favoring reduced genome size and complexity. The discovery that mitochondrial mutation rates can differ by orders of magnitude among closely related angiosperm species presents a unique opportunity to test this hypothesis. We sequenced the mitochondrial genomes from two species in the angiosperm genus Silene with recent and dramatic accelerations in their mitochondrial mutation rates. Contrary to theoretical predictions, these genomes have experienced a massive proliferation of noncoding content. At 6.7 and 11.3 Mb, they are by far the largest known mitochondrial genomes, larger than most bacterial genomes and even some nuclear genomes. In contrast, two slowly evolving Silene mitochondrial genomes are smaller than average for angiosperms. Consequently, this genus captures approximately 98% of known variation in organelle genome size. The expanded genomes reveal several architectural changes, including the evolution of complex multichromosomal structures (with 59 and 128 circular-mapping chromosomes, ranging in size from 44 to 192 kb). They also exhibit a substantial reduction in recombination and gene conversion activity as measured by the relative frequency of alternative genome conformations and the level of sequence divergence between repeat copies. The evolution of mutation rate, genome size, and chromosome structure can therefore be extremely rapid and interrelated in ways not predicted by current evolutionary theories. Our results raise the hypothesis that changes in recombinational processes, including gene conversion, may be a central force driving the evolution of both mutation rate and genome structure.


Via Biswapriya Biswavas Misra
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Scooped by Faith Wu
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Mitochondrial DNA

For more information, log on to- http://shomusbiology.weebly.com/ Download the study materials here- http://shomusbiology.weebly.com/bio-materials.html Mitoc...
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Rescooped by Faith Wu from DNA and RNA research
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A gluttonous plant reveals how its cellular power plant devours foreign DNA

A gluttonous plant reveals how its cellular power plant devours foreign DNA | plant genome | Scoop.it

Amborella trichopoda, a sprawling shrub that grows on just a single island in the remote South Pacific, is the only plant in its family and genus. It is also one of the oldest flowering plants, having branched off from others about 200 million years ago. Now, researchers from Indiana University, with the U.S. Department of Energy Joint Genome Institute (DOE JGI), Penn State University, and the Institute of Research for Development in New Caledonia, have determined a remarkable expansion of the genome of the plant’s critical energy-generating structures. Its mitochondria, the plant’s energy-producing organelles, in an epic demonstration of horizontal gene transfer, have acquired six genome equivalents of foreign DNA -- one from a moss, three from green algae and two from other flowering plants.  It is the first time that an organelle has captured entire “foreign” genomes, those from other organisms, and the first description of a land plant acquiring genes from green algae.


Via Integrated DNA Technologies
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