Question

Which gene is directly associated with shoot apical meristem formation?

• A. RCM1
• B. CLAVATA3
• C. PTN1
• D. QC25

Hint:

Associate CLAVATA (CLV) and WUSCHEL (WUS) with the Shoot (SAM). They are the "thermostat" that keeps the shoot growing correctly.

Answer 1

The Correct Option is B

Concept: The Shoot Apical Meristem (SAM) is maintained by a delicate balance between cell division and cell differentiation, controlled by a specific feedback loop of genes.

Step 1: The WUS/CLV Pathway.
The most critical genetic pathway for SAM maintenance and formation is the WUSCHEL (WUS) - CLAVATA (CLV) feedback loop. WUSCHEL promotes stem cell identity, while the CLAVATA genes act to limit the size of the stem cell population.

Step 2: Identifying the Role of CLAVATA3.
CLAVATA3 (CLV3) is a small signaling peptide expressed in the outermost layers of the SAM. It binds to receptors (like CLV1) to signal the down-regulation of WUS, ensuring the meristem does not grow too large. Because it is a central marker and regulator of the SAM stem cell niche, it is directly associated with its formation and maintenance.

Step 3: Evaluating Others.
QC25 is typically a marker for the Quiescent Center in the root apical meristem, not the shoot. RCM1 and PTN1 are not standard primary regulators of SAM formation in the context of general plant biotechnology curriculum.