Molecular Biotechnology

, Volume 49, Issue 2, pp 116–128

Synonymous Codon Usage, GC3, and Evolutionary Patterns Across Plastomes of Three Pooid Model Species: Emerging Grass Genome Models for Monocots


DOI: 10.1007/s12033-011-9383-9

Cite this article as:
Sablok, G., Nayak, K.C., Vazquez, F. et al. Mol Biotechnol (2011) 49: 116. doi:10.1007/s12033-011-9383-9


We have analyzed factors affecting the codon usage pattern of the chloroplasts genomes of representative species of pooid grass family. Correspondence analysis of relative synonymous codon usages (RSCU) showed that genes on secondary axis were correlated with their GC3S values (all r > 0.3, p < 0.05), indicating mutational bias as an important selective force that shaped the variation in the codon usage among chloroplast genes. The Nc-plot showed that although a majority of the points with low-Nc values were lying below the expected curve, a few genes lied on the expected curve. Nc plot clearly showed that mutational bias plays a major role in codon biology across the monocot plastomes. The hydrophobicity and aromaticity of encoded proteins of each species were found to be other factors of codon usage variation. In the view of above light, besides natural selection, several other factors also likely to be involved in determining the selective constraints on codon bias in plastomes of pooid grass genomes. In addition, five codons (B. distachyon), seven codons (H. vulgare), and four codons (T. aestivum) were identified as optimal codons of the three grass chloroplasts. To identify genes evolving under positive selection, rates of nonsynonymous substitutions (Ka) and synonymous substitutions (Ks) were computed for all groups of orthologous gene pairs.


Brachypodium distachyon Triticum aestivum Hordeum vulgare subsp. vulgare Correspondence analysis GC3 biology Mutational bias 

Supplementary material

12033_2011_9383_MOESM1_ESM.ppt (815 kb)
Supplementary material 1 (PPT 815 kb)

Copyright information

© Springer Science+Business Media, LLC 2011

Authors and Affiliations

  1. 1.Key Lab of Horticultural Plant Biology (MOE)Huazhong Agricultural UniversityWuhanChina
  2. 2.Department of BiotechnologyBioinformatics Centre, Institute of Life SciencesBhubaneswarIndia
  3. 3.Zurich-Basel Plant Science CenterBotanical Institute, University of BaselBaselSwitzerland
  4. 4.Division of Mathematics and StatisticsUniversity of GlamorganPontypriddUK

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