Prelims 2014 · archive
HardConsider the following techniques/ phenomena:
- 1.Budding and grafting in fruit plants
- 2.Cytoplasmic male sterility
- 3.Gene silencing
Which of the above is/are used to create transgenic crops?
Answer & explanation
Answer: (b) 2 and 3
The answer is (b): 2 and 3. A transgenic crop carries a gene introduced by genetic engineering. Gene silencing (RNA interference) and engineered cytoplasmic male sterility are both used to make such crops. Budding and grafting only join plant parts and add no new gene.
- ✗ 1. Budding and grafting are methods of vegetative propagation. A bud or shoot of one plant is joined onto another. No gene is transferred, so the plant is not transgenic.
- ✓ 2. Male sterility is used in genetic engineering to help produce hybrid seed. In one example, a CMS-associated gene, orf220, was expressed in the mitochondria of Brassica juncea. The resulting transgenic plants were male-sterile: most produced no pollen, and some produced only weak pollen.
- ✓ 3. In RNA interference (RNAi), a specific mRNA is silenced by a complementary double-stranded RNA. This is used to make transgenic plants. For example, tobacco plants were given nematode-specific genes that produce both sense and antisense RNA. This silenced the nematode's mRNA and protected the plants.
- • remember
Remember · Transgenic means a foreign gene is inserted. RNAi gene silencing and engineered male sterility are used to make transgenic crops; budding and grafting are only vegetative propagation.
📘 Read it in NCERT: Class 12 Biology, Ch 10 (practise this chapter) · Class 10 Science, Ch 7 (practise this chapter)
Sources
- NCERT Class 12 · Biology, Chapter 10 “RNAi takes place in all eukaryotic organisms as a method of cellular defense. This method involves silencing of a specific mRNA due to a complementary dsRNA molecule”
- NCERT Class 10 · Science, Chapter 7 “This property of vegetative propagation is used in methods such as layering or grafting to grow many plants like sugarcane, roses, or grapes for agricultural purposes.”
- Mitochondrially-targeted expression of a cytoplasmic male sterility-associated orf220 gene causes male sterility in Brassica juncea (BMC Genomics, via US National Library of Medicine PMC) ↗ “Transgenic plants were male-sterile, most being unable to produce pollen while some could only produce non-vigorous pollen.”
Question: UPSC Civil Services (Preliminary) 2014, General Studies paper. Explanation: Minimalist IAS, checked 25 Oct 2026 (how we verify). ·