Question

how does STM gene contribute to maintaining SAM (shoot apical meristem) organization?

Answer 1

STM (shoot meristemless) gene contributes to maintaining SAM (shoot apical meristem) organisation as:
1. It  functions to organize undifferentiated cells into a self-sustaining meristem.
2. STM is required for continued stem cell function in the SAM(shoot apical meristem) by keeping active the expression of the stem cell-promoting factor (WUS) and it prevents the cells of the meristem organizing center from growing and gaining lateral organ-specific fates.
3. STM (shoot meristemless) is required by  SAM during embryogenesis and its subsequent maintenance throughout the plant life-cycle.
4. STM is required to maintain WUS expression and its function in SAM organization cannot be replaced by cytokinin.
5. STM plays its regulatory interactions with other KNOX genes.
6. STM also promotes cytokinin synthesis.
Through all these STM helps in organisation of Shoot apical meristem.