Correct option is B
The correct answer is (b) Glucosinolates. Methionine serves as a precursor for glucosinolates in Arabidopsis thaliana. Glucosinolates are sulfur-containing secondary metabolites derived from amino acids. They play an essential role in plant defense against herbivores and pathogens. In Arabidopsis, methionine-derived glucosinolates belong to the class of aliphatic glucosinolates, which are critical for chemical defense and stress tolerance.
Information Booster:
- Glucosinolates are primarily found in the Brassicaceae family, including Arabidopsis thaliana, broccoli, and mustard.
- Methionine-derived glucosinolates are aliphatic and contribute to the plant's resistance against herbivores.
- The biosynthetic pathway includes the elongation of methionine followed by core structure formation and side-chain modifications.
- Glucosinolates, when hydrolyzed, produce biologically active compounds such as isothiocyanates and nitriles.
- Methionine-derived glucosinolates are essential for cross-species defense signaling.
Additional Knowledge:
(a) Alkaloids:
This option is incorrect. Alkaloids are nitrogen-containing compounds primarily derived from other amino acids like tryptophan, tyrosine, or ornithine. Methionine is not a direct precursor for alkaloid biosynthesis.
(b) Glucosinolates:
This option is correct. Methionine is a key precursor in the biosynthesis of aliphatic glucosinolates. These secondary metabolites contribute to plant defense by deterring herbivores and pathogens.
(c) Phenolics:
This option is incorrect. Phenolic compounds, such as flavonoids, lignins, and tannins, are typically derived from the shikimate pathway, involving phenylalanine as a precursor, not methionine.
(d) Terpenoids:
This option is incorrect. Terpenoids are derived from isoprenoid pathways, specifically involving precursors like isopentenyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DMAPP). Methionine is not involved in this biosynthesis pathway.
