Skip Navigation



AOBPreview published online on November 3, 2009
Annals of Botany, doi:10.1093/aob/mcp272
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Supplementary Data
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrowRequest Permissions
Google Scholar
Right arrow Articles by Liao, P.-C.
Right arrow Articles by Hwang, S.-Y.
PubMed
Right arrow PubMed Citation
Right arrow Articles by Liao, P.-C.
Right arrow Articles by Hwang, S.-Y.
Agricola
Right arrow Articles by Liao, P.-C.
Right arrow Articles by Hwang, S.-Y.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

© The Author 2009. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oxfordjournals.org

Duplication of the class I cytosolic small heat shock protein gene and potential functional divergence revealed by sequence variations flanking the {alpha}-crystallin domain in the genus Rhododendron (Ericaceae)

Pei-Chun Liao1, Tsan-Piao Lin2, Wei-Chieh Lan3, Jeng-Der Chung4 and Shih-Ying Hwang5,*

1 Department of Life Science, Pingtung University of Science and Technology, Pingtung 91201, Taiwan
2 Institute of Plant Biology, National Taiwan University, 1 Roosevelt Road, Section 4, Taipei 10617, Taiwan
3 Graduate Institute of Biotechnology, Chinese Culture University, 55 Hwagang Road, Yangmingshan, Taipei 11114, Taiwan
4 Division of Silviculture, Taiwan Forestry Research Institute, 53 Nanhai Road, Taipei 10066, Taiwan
5 Department of Life Science, National Taiwan Normal University, Taipei 11677, Taiwan

* For correspondence. E-mail hsy9347{at}ntnu.edu.tw

Received: 8 July 2009    Returned for revision: 11 September 2009    Accepted: 5 October 2009   

Background and Aims: Positive selection in the {alpha}-crystallin domain (ACD) of the chloroplast small heat shock protein (CPsHSP) gene was found in a previous study and was suggested to be related to the ecological adaptation of Rhododendron species in the subgenus Hymenanthes. Consequently, it was of interest to examine whether gene duplication and subsequent divergence have occurred in other sHSP genes, for example class I cytosolic sHSP genes (CT1sHSPs) in Rhododendron in Taiwan, where many endemic species have evolved as a result of habitat differentiation.

Methods: A phylogeny of CT1sHSP amino acid sequences was built from Rhododendron, Arabidopsis thaliana, Oryza sativa, Populus trichocarpa, Vitis vinifera and other species for elucidation of the phylogenetic relationships among CT1sHSPs. Phylogenies of Rhododendron CT1sHSP nucleotide and amino acid sequences were generated for positive selection and functional divergence analysis, respectively. Positively selected sites and amino acid differences between types of Rhododendron CT1sHSPs were mapped onto the wheat sHSP16·9 protein structure. Average genetic distance (Dxy) and dN/dS ratios between types of Rhododendron CT1sHSP genes were analysed using sliding window analysis. Gene conversion was also assessed between types of Rhododendron CT1sHSPs.

Key Results: Two types of Rhododendron CT1sHSP were identified. A high level of genetic similarity and diversity within and flanking the ACD, respectively, between types of Rhododendron CT1sHSP were found. Main differences between the two types of Rhododendron CT1sHSPs were: (1) increased hydrophobicity by two positively selected amino acid sites and a seven-amino-acid insertion in the N-terminal arm; and (2) increased structural flexibility and solubility by a seven-amino-acid insertion in the N-terminal arm and one positively selected amino acid site in the C-terminal extension.

Conclusions: Functional conservation of the ACD of Rhododendron CT1sHSP genes was inferred because of strong purifying selection. However, sequence variations flanking the ACD in Rhododendron CT1sHSP gene duplicates may have resulted in functional divergence and played important roles in chaperon function enhancement.

Key words: {alpha}-crystallin domain (ACD), cytosolic class I small heat shock protein (CT1sHSP), gene duplication, hydrophobicity, positive selection, purifying selection, Rhododendron, structural flexibility and solubility


Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?




Disclaimer: Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.