FIGURE 1.

Schematic representation of phytomers with different developmental fates and AM developmental stages marked by the expression of STM. (A–C) A reproductive primordium develops as a bias in the meristem suppresses expression of leaf domain genes. Instead, the meristem maintains STM expression and high levels of LFY and AP1 expression (Grbic, 2005). (D–F) A transitional primordium develops leaf and axillary meristems (AMs) concomitantly. The floral meristem identity gene LFY and the shoot meristem identity gene TFL1 (brown color) are expressed at high levels in this primordium (Ratcliffe et al., 1999), which confers mixed features of both leaf and flower primordia. This primordium develops into a cauline phytomer. (G–I) A vegetative primordium develops with the leaf domain prevailing, due to biases toward leaf fate, resulting in a rosette phytomer. (J–M) AM initiation in the leaf axils. The blank region of (M) without STM expression indicates primordium initiation. Asterisks indicate that the expression pattern is postulated and not verified by experiments.