Question

Which gene in shoot apical meristem (SAM) negatively regulate WUS expression?

• A. CLV
• B. STM
• C. AP1
• D. TAB1

Hint:

Memorize the WUS-CLV feedback loop: {WUS} promotes stem cells, stem cells make {CLV3}, and {CLV} signaling pathway inhibits {WUS}. It's a classic example of negative feedback in developmental biology.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
The question is about the genetic regulation of the shoot apical meristem (SAM), specifically the negative feedback loop that controls the stem cell population.
Step 2: Detailed Explanation:
The maintenance of the stem cell population in the SAM is controlled by a feedback loop involving the WUSCHEL (WUS) and CLAVATA (CLV) genes.
WUS is expressed in the organizing center (below the stem cells) and sends a signal upwards to promote stem cell identity.
The stem cells, in turn, express the CLV3 gene, which encodes a small peptide.
This CLV3 peptide diffuses and binds to the CLV1/CLV2 receptor complex on the cells of the organizing center.
The activation of the CLV signaling pathway negatively regulates or represses the expression of the WUS gene.
This negative feedback loop ensures that the stem cell population remains stable. If WUS is too active, it leads to more stem cells, which produce more CLV3, which in turn shuts down WUS. Therefore, the CLV gene family negatively regulates WUS expression.
STM (SHOOT MERISTEMLESS) is required for the formation of the SAM, while AP1 (APETALA1) is involved in flower development.
Step 3: Final Answer:
The CLV genes negatively regulate WUS expression in the shoot apical meristem.