Figure 8.

Model depicting the likely mechanism of OsMADS1 action in regulating meristem specification, determinacy, and organ differentiation through different stages of floret development. Gray dots depict the spatial domains of OsMADS1 expression in a young spikelet with an incipient FM, in a young floret at the early stages of lateral organ patterning, and in a differentiated floret. OsMADS1 and its partners in various complexes directly repress OsMADS34 to promote the transition from spikelet to FM. It activates other meristem regulators and genes in the auxin signaling pathway. These events could regulate early events in meristem specification, its floral fate, and lateral primordia differentiation. OsMADS1-containing complexes are also negative regulators of the cytokinin pathway that can contribute to meristem determinacy. These pathways and the cross talk between them in developing florets culminate in a determinate meristem, with its typically differentiated organs.