Research article

Phylogenetic analysis and molecular evolution of the dormancy associated MADS-box genes from peach

Sergio Jiménez¹ , Amy L Lawton-Rauh² , Gregory L Reighard¹ , Albert G Abbott² and Douglas G Bielenberg^1,3

¹  Department of Horticulture, Clemson University, Clemson, SC 29634-0319, USA

²  Department of Genetics & Biochemistry, Clemson University, Clemson, SC 29634-0318, USA

³  Department of Biological Sciences, Clemson University, Clemson, SC 29634-0314, USA

author email corresponding author email

BMC Plant Biology 2009, 9:81doi:10.1186/1471-2229-9-81

Published:	27 June 2009

Abstract

Background

Dormancy associated MADS-box (DAM) genes are candidates for the regulation of growth cessation and terminal bud formation in peach. These genes are not expressed in the peach mutant evergrowing, which fails to cease growth and enter dormancy under dormancy-inducing conditions. We analyzed the phylogenetic relationships among and the rates and patterns of molecular evolution within DAM genes in the phylogenetic context of the MADS-box gene family.

Results

The peach DAM genes grouped with the SVP/StMADS11 lineage of type II MIKC^C MADS-box genes. Phylogenetic analyses suggest that the peach SVP/StMADS11-like gene family, which contains significantly more members than annual model plants, expanded through serial tandem gene duplication. We found evidence of strong purifying selection acting to constrain functional divergence among the peach DAM genes and only a single codon, located in the C-terminal region, under significant positive selection.

Conclusion

Because all DAM genes are expressed in peach and are subjected to strong purifying selection we suggest that the duplicated genes have been maintained by subfunctionalization and/or neofunctionalization. In addition, this pattern of selection suggests that the DAM genes are important for peach growth and development.