Plant & Animal Genomes XVI Conference

January 12-16, 2008
Town & Country Convention Center
San Diego, CA

Duplicated Mikc-Type MADS-Box Genes Are Candidates For The Evergrowing Mutation In Peach: Phylogenetic Context, Duplication History, And Expression Analysis.

Zhigang Li¹ , Sergio Jimenez-Tarodo¹ , Amy Lawton-Rauh² , Gregory L Reighard¹ , Albert G Abbott² , Douglas G Bielenberg^1,3

¹  Department of Horticulture, Clemson University, Clemson, SC 29634-0319 U.S.A.

²  Department of Genetics & Biochemistry, Clemson University, Clemson, SC 29634-0318 U.S.A.

³  Department of Biological Sciences, Clemson University, Clemson, SC 29634-0314 U.S.A.

The evergrowing mutant of peach (Prunus persica L. [Batsch]) is a naturally occurring dormancy-incapable genotype. We have mapped, cloned, and sequenced the genomic locus of evergrowing in wild-type trees. The locus contains a duplicated array of six MIKC-type MADS box transcription factors which we have designated Ppdam1 through 6 (Prunus persica dormancy associated MADS). Expression of all six of the genes is lost in the mutant trees and is associated with an approximately 41 kb genomic deletion. The six MADS-box genes are members of the StMADS11/SVP clade of MADS-box genes and make up a monophyletic group when aligned with Arabidopsis and Populus sequences. The tandem array of genes appears to have resulted from successive duplications of individual genes from a single common ancestor. Quantitative expression of the six Ppdam genes was determined every two weeks through an annual cycle in field-grown wild-type trees. Expression was also measured in a controlled environment in response to reduction in photoperiod (LD to SD). With exception of Ppdam3, the genes show distinct seasonal expression patterns that can be correlated with the expression responses to photoperiod under controlled conditions.