Mosaico esplêndido de genes mitocondriais criados pela transferência horizontal e conversão de gene

terça-feira, novembro 30, 2010

Gorgeous mosaic of mitochondrial genes created by horizontal transfer and gene conversion

Weilong Hao1,2, Aaron O. Richardson1, Yihong Zheng3, and Jeffrey D. Palmer4

+Author Affiliations

Department of Biology, Indiana University, Bloomington, IN 47405

↵2Present address: Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada M5G 1L5.

↵3Present address: College of Life Sciences, Wuhan University, Wuhan 430072, China.

Contributed by Jeffrey D. Palmer, November 1, 2010 (sent for review September 17, 2010)

↵1W.H. and A.O.R. contributed equally to this work.


The best known outcome of horizontal gene transfer (HGT) is the introduction of novel genes, but other outcomes have been described. When a transferred gene has a homolog in the recipient genome, the native gene may be functionally replaced (and subsequently lost) or partially overwritten by gene conversion withtransiently present foreign DNA. Here we report the discovery, in two lineages of plant mitochondrial genes, of novel gene combinations that arose by conversion between coresident native and foreign homologs. These lineages have undergone intricate conversion between native and foreign copies, with conversion occurring repeatedly and differentially over the course of speciation, leading to radiations of mosaic genes involved in respiration and intron splicing. Based on these findings, we develop a model—the duplicative HGT and differential gene conversion model—that integrates HGT and ongoing gene conversion in the context of speciation. Finally, we show that one of these HGT-driven gene-conversional radiations followed two additional types of conversional chimerism, namely, intramitochondrial retroprocessing and interorganellar gene conversion across the 2 billion year divide between mitochondria and chloroplasts. These findings expand our appreciation of HGT and gene conversion as creative evolutionary forces, establish plant mitochondria as a premiere system for studying the evolutionary dynamics of HGT and its genetic reverberations, and recommend careful examination of bacterial and other genomes for similar, likely overlooked phenomena.

gene duplication, recombination


4To whom correspondence should be addressed.

Author contributions: W.H., A.O.R., and J.D.P. designed research; W.H., A.O.R., and Y.Z. performed research; W.H., A.O.R., and J.D.P. analyzed data; and W.H., A.O.R., and J.D.P. wrote the paper.

The authors declare no conflict of interest.

Data deposition: The sequences reported in this paper have been deposited in the GenBank database (accession nos. HQ437915–HQ437987).

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