DOG1-like genes in cereals: investigation of their function by means of ectopic expression in Arabidopsis.

The Arabidopsis gene DOG1 (AtDOG1) functions in seed dormancy and in sugar signaling. Little is known about the structural and functional features of plant genes homologous to AtDOG1, except for one type (clade 1) of Triticeae AtDOG1-like genes, which was previously demonstrated to be functionally orthologous to AtDOG1. Here, through phylogenetic, structural, and functional analyses of cereal AtDOG1-like genes, we characterized their features: these genes exist as a gene family that can be classified into five distinct clades (1-5). Of these, AtDOG1-like genes in clades 1-4 have a similar architecture to AtDOG1: they encode proteins with three conserved regions. In contrast, the clade 5 genes are distinct; their encoded proteins lack these conserved regions, but harbor domains that interact with DNA. Ectopic expression of the cereal AtDOG1-like genes of clades 2-4 in Arabidopsis demonstrated that like the clade 1 genes, they performed the same function as AtDOG1. The correlation between the depth of seed dormancy and the efficiency of sugar signaling in transgenic Arabidopsis conferred by genes in clades 1-4 suggests a close link in the underlying mechanisms between the seed dormancy and sugar signaling functions of AtDOG1.