In maize, the opaque 2 mutants are found to have some of the following quality parameters. Identify -
Show Hint
- High methionine and high lysine
- High methionine and high tryptophan
- High lysine and high tryptophan
- High lysine and high proline
The Correct Option is C
Solution and Explanation
Normal maize endosperm protein (zein) is nutritionally poor because it is deficient in two essential amino acids: lysine and tryptophan.
Opaque-2 is a recessive gene mutation in maize that drastically alters the protein profile of the endosperm.
Step 2: Detailed Explanation:
The opaque-2 ($o2$) gene encodes a transcription factor that regulates the synthesis of storage proteins.
In $o2$ mutant maize, the synthesis of the lysine-poor zein proteins is suppressed.
Simultaneously, the synthesis of non-zein proteins (such as glutelins, albumins, and globulins) is upregulated.
Because these non-zein proteins are naturally rich in lysine and tryptophan, the mutant endosperm contains nearly double the amount of these two essential amino acids compared to standard maize.
This discovery served as the biological foundation for developing Quality Protein Maize (QPM) varieties, which have improved nutritional quality for humans and monogastric animals.
Step 3: Final Answer:
The opaque-2 mutant is characterized by high lysine and high tryptophan content. Therefore, the correct option is (C).
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