Abstract
Choice of Arabidopsis thaliana as a model in mid 1980s made molecular genetic studies of plant developmental processes much easier than before. We started genetic analyses of plant organ development, particularly in axis-dependent tissue differentiation in lateral organs, such as leaves, young floral buds and floral organs. They develop from primordia formed at the fixed position in the peripheral region of shoot apical meristem, and are considered to follow three axes; basal-apical, central-marginal, and adaxial-abaxial. We examined mechanism of the abaxial-side specific gene, FIL, and the adaxial-side specific gene, PHB, and showed that FIL expression is owing to two cis elements, and that PHB expression is controlled by microRNAs which is expressed at the abaxial side, suggesting that the two sides in lateral organ primordia mutually control specific gene expression. In addition, we showed that the marginal cell-specific genes, PRS and WOX1, are involved in the action of leaf margin as a boundary separating tissues specific to the adaxial and the abaxial sides. We are further investigating intercellular signaling factors controlling the axis-dependent development.
