These authors contributed equally to the article.
Molecular, phylogenetic and comparative genomic analysis of the cytokinin oxidase/dehydrogenase gene family in the Poaceae
Article first published online: 15 AUG 2011
© 2011 National Institute of Agricultural Botany (NIAB). Plant Biotechnology Journal © 2011 Society for Experimental Biology, Association of Applied Biologists and Blackwell Publishing Ltd
Plant Biotechnology Journal
Volume 10, Issue 1, pages 67–82, January 2012
How to Cite
Mameaux, S., Cockram, J., Thiel, T., Steuernagel, B., Stein, N., Taudien, S., Jack, P., Werner, P., Gray, J. C., Greenland, A. J. and Powell, W. (2012), Molecular, phylogenetic and comparative genomic analysis of the cytokinin oxidase/dehydrogenase gene family in the Poaceae. Plant Biotechnology Journal, 10: 67–82. doi: 10.1111/j.1467-7652.2011.00645.x
- Issue published online: 6 DEC 2011
- Article first published online: 15 AUG 2011
- Received 7 April 2011; accepted 20 June 2011.
- molecular phylogeny;
- comparative mapping;
- cytokinin oxidase;
- cytokinin oxidase/dehydrogenases 2
The genomes of cereals such as wheat (Triticum aestivum) and barley (Hordeum vulgare) are large and therefore problematic for the map-based cloning of agronomicaly important traits. However, comparative approaches within the Poaceae permit transfer of molecular knowledge between species, despite their divergence from a common ancestor sixty million years ago. The finding that null variants of the rice gene cytokinin oxidase/dehydrogenase 2 (OsCKX2) result in large yield increases provides an opportunity to explore whether similar gains could be achieved in other Poaceae members. Here, phylogenetic, molecular and comparative analyses of CKX families in the sequenced grass species rice, brachypodium, sorghum, maize and foxtail millet, as well as members identified from the transcriptomes/genomes of wheat and barley, are presented. Phylogenetic analyses define four Poaceae CKX clades. Comparative analyses showed that CKX phylogenetic groupings can largely be explained by a combination of local gene duplication, and the whole-genome duplication event that predates their speciation. Full-length OsCKX2 homologues in barley (HvCKX2.1, HvCKX2.2) and wheat (TaCKX2.3, TaCKX2.4, TaCKX2.5) are characterized, with comparative analysis at the DNA, protein and genetic/physical map levels suggesting that true CKX2 orthologs have been identified. Furthermore, our analysis shows CKX2 genes in barley and wheat have undergone a Triticeae-specific gene-duplication event. Finally, by identifying ten of the eleven CKX genes predicted to be present in barley by comparative analyses, we show that next-generation sequencing approaches can efficiently determine the gene space of large-genome crops. Together, this work provides the foundation for future functional investigation of CKX family members within the Poaceae.