Figure 2: Mutant secondary inflorescences replaced by vegetative branches in pea veg1.

(a) Pea wild-type (WT) and veg1 plants grown for 11 weeks. Whereas the upper nodes of the wild type contain secondary inflorescences (I₂) with flowers (pods, arrowheads), veg1 has not produced any flower. (b) The same plants as in (a), where leaves have been removed. As in the wild type, the axillary buds of the lower nodes of veg1 remain dormant. However, at the nodes where I₂s (arrowheads) have grown in the wild type, branches (arrowheads) have grown out in veg1. (c) Diagrams (top) and schematic representation of meristem identity (bottom) of the wild-type and veg1 mutant plants. The vegetative meristem (V) becomes a primary inflorescence meristem (I₁) that produces secondary inflorescence meristems (I₂) that form flowers (F). In the veg1 plants the I₂s are replaced by vegetative branches similar to I₁s (I₁*). Arrowheads, indeterminate shoots; open circles, flowers; orange triangles, stubs. (d) Structures formed in equivalent apical nodes of the inflorescence stems of wild-type and veg1 plants. Whereas the wild type has produced an I₂ with two flowers and a stub (arrowhead in inset), veg1 has produced a vegetative branch. (e) Scanning electron micrographs of the main shoot apex of wild type and veg1. During the vegetative phase (top), in both the wild type and veg1, the vegetative SAM (V, highlighted in green) generates leaves with dormant axillary meristems. After transition to flowering (bottom), the SAM in the wild type becomes a primary inflorescence meristem (I₁) that produces I₂ meristems (orange) with floral meristems (F, pink). At an equivalent developmental stage, the SAM of veg1 produces leaves with axillary meristems (I₁*, green) that grow out following the same pattern as the I₁ meristem. Scale bars, 200 μm.