Adams, Keith L. and Song, Keming and Roessler, Philip G. and Nugent, Jacqueline M. and Doyle, Jane L. and Doyle, Jeff J. and Palmer, Jeffrey D. (1999) Intracellular gene transfer in action: Dual transcription and multiple silencings of nuclear and mitochondrial cox2 genes in legumes. Proceedings of the National Academy of Sciences, 96 (24). pp. 13863-13868. ISSN 1091-6490

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Abstract

The respiratory gene cox2, normally present in the mitochondrion, was previously shown to have been functionally transferred to the nucleus during flowering plant evolution, possibly during the diversification of legumes. To search for novel intermediate stages in the process of intracellular gene transfer and to assess the evolutionary timing and frequency of cox2 transfer, activation, and inactivation, we examined nuclear and mitochondrial (mt) cox2 presence and expression in over 25 legume genera and mt cox2 presence in 392 genera. Transfer and activation of cox2 appear to have occurred during recent legume evolution, more recently than previously inferred. Many intermediate stages of the gene transfer process are represented by cox2 genes in the studied legumes. Nine legumes contain intact copies of both nuclear and mt cox2, although transcripts could not be detected for some of these genes. Both cox2 genes are transcribed in seven legumes that are phylogenetically interspersed with species displaying only nuclear or mt cox2 expression. Inactivation of cox2 in each genome has taken place multiple times and in a variety of ways, including loss of detectable transcripts or transcript editing and partial to complete gene loss. Phylogenetic evidence shows about the same number (3-5) of separate inactivations of nuclear and mt cox2, suggesting that there is no selective advantage for a mt vs. nuclear location of cox2 in plants. The current distribution of cox2 presence and expression between the nucleus and mitochondrion in the studied legumes is probably the result of chance mutations silencing either cox2 gene.

Item Type:	Article
Keywords:	Intracellular; gene transfer; cox2 genes; legumes;
Academic Unit:	Faculty of Science and Engineering > Biology
Item ID:	7419
Identification Number:	https://doi.org/10.1073/pnas.96.24.13863
Depositing User:	Dr. Jacqueline Nugent
Date Deposited:	31 Aug 2016 15:13
Journal or Publication Title:	Proceedings of the National Academy of Sciences
Publisher:	National Academy of Sciences
Refereed:	Yes
URI:	http://www.pnas.org
Use Licence:	This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here

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