A nematode which infects the roots of tobacco plants and causes a great reduction in yield is:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Meloidegyne incognitia
Meloidegyne incognitia is a nematode (roundworm) that lives in the roots of tobacco plants and greatly lowers the yield. It is the example used for RNA interference (RNAi). Genes of the nematode were put into the plant so that the plant made both sense and anti-sense RNA. These formed double-stranded RNA, which silenced the matching mRNA of the nematode. The parasite could not survive in such a transgenic plant.
(1) Ascaris — Incorrect. Ascaris is a roundworm of the human intestine. It causes ascariasis in humans, not a disease of tobacco roots.
(2) Meloidegyne incognitia — Correct. This nematode infects tobacco roots and was controlled by RNAi.
(3) Wuchereria — Incorrect. Wuchereria is a filarial worm of humans. It lives in the lymphatic vessels and causes elephantiasis.
(4) Earthworm — Incorrect. The earthworm is an annelid, not a nematode. It is useful to the soil and does not harm plant roots.
Note: A similar question was also asked in CUET (UG) 2025 on 14-05-2025 (Slot 2).
NCERT Extract:
Biotechnological Applications in Agriculture – “… Pest Resistant Plants: Several nematodes parasitise a wide variety of plants and animals including human beings. A nematode Meloidegyne incognitia infects the roots of tobacco plants and causes a great reduction in yield. A novel strategy was adopted to prevent this infestation which was based on the process of RNA interference (RNAi).”