Ancestral MADS box genes in sugi, Cryptomeria japonica D. Don (Taxodiaceae), homologous to the B function genes in angiosperms

In flowering plants, flower organ identity is controlled by the ABC genes, including several MADS box genes. We present two MADS box genes of a conife r, Cryptomeria japonica D, Don, The genes, CjMADS1 and CjMADS2, were relate d to the angiosperm B function genes which determine the identities of peta ls and stamens. A phylogenetic analysis showed that these genes form a new clade outside the angiosperm B group, that is, PISTILLATA (PI) and APETALA3 (AP3) lineages. CjMADS1 had a PI-group specific motif and CjMADS2 had AP3- group specific motifs at the C terminal end, respectively. CjMADS1 was expr essed in male strobili (or cones) throughout its development, while CjMADS2 was transiently expressed during male strobilus development. The specific expression in the male reproductive organ indicated that the B function is maintained in gymnosperms, Our cladistic analysis suggests that the gene du plication event which generated B function gene lineages predates the diver gence of angiosperms and gymnosperms and that the gene duplication which pr oduced the two genes of C. japonica occurred in an ancestral conifer specie s.