Cloning and Characterization of Apple Class B MADS-box Genes Including a Novel AP3 Homologue MdTM6.

Abstract

Three cDNA clones (MdiPI, MdTM6 and MdiMADS13) homologous to class-B MADS-box protein were isolated from Mains domestica Borkh. 'Indo'. From the sequence similarity, MdiPI is thought to be a homologue of PISTILLASTA (PI), while MdTM6 and MdiMAD13 are homologues of APETALA3 (AP3). MdiPI and MdiMADS13 are possibly counterparts of apple MdPI and MdMADS13 in 'Indo', respectively, whereas MdTM6 is considered to be a novel AP3 homologue. Both MdTM6 and MdiMADS13 are close to TM6 lineage members based on phylogenetic analysis in addition to the presence of the PI motif-derived, and paleo AP3 motif at the C-terminal region. MdTM6 and MdiMADS13 genes showed the same expression patterns, mainly, in petals and stamens which suggests that both genes have the same function for AP3 homologues. This is the first case of two TM6 lineage genes existing in one plant.