Abstract
Recent genomic projects reveal that about half of the gene repertoire in plant genomes is made up by multigene families. In this paper, a set of structural and phylogenetic analyses have been applied to compare the differently sized nicotianamine synthase (NAS) gene families in barley and rice. Nicotianamine acts as a chelator of iron and other heavy metals and plays a key role in uptake, phloem transport and cytoplasmic distribution of iron, challenging efforts for the breeding of iron-efficient crop plants. Nine barley NAS genes have been mapped, and co-linearity of flanking genes in barley and rice was determined. The combined analyses reveal that the NAS multigene family members in barley originated through at least one duplication event that occurred before the divergence of rice and barley. Additional duplications appear to have occurred within each of the species. Although we detected no evidence for positive selection of recently duplicated genes within species, codon-based tests revealed evidence for positive selection having contributed to the divergence of some amino acids. The integrated comparative and phylogenetic analysis improved our current view of NAS gene family evolution, might facilitate the functional characterization of individual members and is applicable to other multigene families.
Original language | English (US) |
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Pages (from-to) | 169-179 |
Number of pages | 11 |
Journal | Functional and Integrative Genomics |
Volume | 7 |
Issue number | 2 |
DOIs | |
State | Published - Apr 2007 |
Bibliographical note
Funding Information:Acknowledgement We thank Prof. P. Hayes for providing seeds of the OWB mapping population and T. Thiel for support in sequence comparison. P. Tiffin thanks the US National Science Foundation for financial support (DEB 0235027).
Keywords
- Barley
- Gene family mapping
- Nicotianamine synthase
- Orthologues and paralogues