Question

Which of the following hormones is synthesized from methionine?

• A. Auxin
• B. Gibberellin
• C. Cytokinin
• D. Ethylene

Hint:

For exams, it's very useful to remember the amino acid precursors for hormones:

\textbf{Tryptophan} \(\rightarrow\) \textbf{Auxin}
\textbf{Methionine} \(\rightarrow\) \textbf{Ethylene}
These two are the most commonly asked pairings.

Answer 1

The Correct Option is D

Step 1: Concept Overview:
The question requires identifying the plant hormone whose synthesis begins with the amino acid methionine.
Step 2: Detailed Elaboration:
Here's a review of the precursor molecules for major plant hormones:

Auxin (specifically IAA) is mainly synthesized from the amino acid tryptophan.

Gibberellin, a terpenoid, is synthesized from GGPP via the MEP or MVA pathway, not from an amino acid.

Cytokinin derives from the purine base adenine.

Ethylene (C₂H₄), a gaseous hormone, is biosynthesized from the amino acid methionine. Methionine is converted to SAM, then to ACC by ACC synthase, and finally to ethylene by ACC oxidase.

Step 3: Conclusion:
Therefore, ethylene is the plant hormone synthesized from methionine.