108. Opaque2 gene in maize and Wx gene in rice affects the …………. and ……… content, respectively.
(1) protein quality, amylose
(2) oil, wax
(3)protein quality, wax
(4)oil, starch

Detailed Explanation:

Question:
Opaque2 gene in maize and Wx gene in rice affect the …………. and ……… content, respectively.

Correct Answer:
(1) protein quality, amylose

Introduction to Crop Quality Genes

Crop genetic improvement aims to enhance nutritional value, taste, texture, and processing qualities. Two prominent genes studied in this context are:

• Opaque2 (O2) in maize

• Waxy (Wx) gene in rice

These genes influence protein quality and amylose content, respectively, thereby affecting the end-use and nutritional benefits of these staple grains.

Opaque2 Gene in Maize – Improving Protein Quality

The Opaque2 (O2) gene in maize is a transcription factor that regulates the expression of zein proteins, which are a major component of maize endosperm storage proteins.

• In the wild-type O2 maize, zein proteins are abundant, but the nutritional value is low due to poor lysine content.

• In the opaque2 mutant, zein synthesis is reduced, and non-zein proteins (richer in lysine and tryptophan) are increased.

Thus, opaque2 maize varieties (e.g., Quality Protein Maize or QPM) are enriched with better amino acid profiles, improving protein quality significantly.

Wx Gene in Rice – Regulating Amylose Content

The Waxy (Wx) gene encodes granule-bound starch synthase I (GBSSI), a key enzyme involved in the biosynthesis of amylose, a linear polysaccharide in starch.

• High expression of the Wx gene results in higher amylose content, leading to firmer, less sticky rice (preferred in long-grain varieties).

• Low or mutated expression of Wx leads to waxy or glutinous rice, which has very low amylose content, resulting in a sticky, soft texture.

Manipulating the Wx gene allows breeders to produce rice varieties suited to different culinary and processing requirements.

Why Option (1) is Correct

• Opaque2 → Protein quality in maize

• Wx → Amylose content in rice

These two genes are directly responsible for modifying essential nutritional and physical traits in two of the world’s most important cereal crops.

Conclusion

Understanding the functions of the Opaque2 gene in maize and the Wx gene in rice provides valuable insights into how modern plant breeding enhances food quality. These genes are central to producing nutrient-rich maize and texture-specific rice, addressing both nutritional needs and consumer preferences.

✅ Final Answer: (1) protein quality, amylose