Abstract
The pattern of molecular evolution of imprinted genes is controversial and the entire picture is still to be unveiled. Recently, a relationship between the formation of imprinted genes and gene duplication was reported in genome-wide survey of imprinted genes in Arabidopsis thaliana. Because gene duplications influence the molecular evolution of the duplicated gene family, it is necessary to investigate both the pattern of molecular evolution and the possible relationship between gene duplication and genomic imprinting for a better understanding of evolutionary aspects of imprinted genes. In this study, we investigated the evolutionary changes of type I MADS-box genes that include imprinted genes by using relative species of Arabidopsis thaliana (two subspecies of A . lyrata and three subspecies of A . halleri ). A duplicated gene family enables us to compare DNA sequences between imprinted genes and its homologs. We found an increased number of gene duplications within species in clades containing the imprinted genes, further supporting the hypothesis that local gene duplication is one of the driving forces for the formation of imprinted genes. Moreover, data obtained by phylogenetic analysis suggested “rapid evolution” of not only imprinted genes but also its closely related orthologous genes, which implies the effect of gene duplication on molecular evolution of imprinted genes.
Highlights
Genomic imprinting is a phenomenon that causes complete or partial uniparental gene expression of particular genes
We investigated the evolutionary changes of type I MADS-box genes, which include imprinted genes, by using relative species of A. thaliana
The origin of other plant materials was as follows: four A. lyrata ssp. petraea strains from Plech Germany; A. halleri ssp. gemmifera strain 144-1 isolated in Mino-shi, Osaka, Japan; A. halleri ssp. tatrica strain T-PLDH1 isolated in Vysoke Tatry, Poland; A. halleri ssp. halleri strain H– RB isolated in Bistrita, Romania; Turritis glabra strain OM isolated in Ohmi-Shirahama, Shiga, Japan; and Crucihimalaya wallichii strain SJS00500 obtained from RIKEN BioResource Center
Summary
Genomic imprinting is a phenomenon that causes complete or partial uniparental gene expression of particular genes (called “imprinted genes”). The methylation status of the differently methylated regions in the proximal region of the imprinted genes between maternal and paternal alleles affects the expression of some imprinted genes [7,8]. It is reported that transposable elements (TEs) are methylated in the embryo but extensively demethylated in the endosperm, affecting the imprinting status of the nearby genes [1]. These results may support the defense theory that the status of imprinting arises as a byproduct of silencing of the invading DNA fragments such as TEs [13]. Together with TEs, gene duplication might affect the imprinting status and evolution of imprinted genes
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call