Which of the following plants had resistance against a nematode introduced through the application of RNAi?

Tobacco

The correct answer is option (3) -Tobacco

The plant in which resistance against a nematode was introduced through the application of RNAi is (c) Tobacco.

In this context, RNA interference (RNAi) was employed as a novel strategy to combat the infestation of the nematode Meloidogyne incognita in tobacco plants. RNAi is a natural defense mechanism found in eukaryotic organisms, including plants, and it involves the silencing of specific genes by using complementary RNA molecules.

To protect tobacco plants from the nematode's harmful effects, scientists likely introduced synthetic double-stranded RNA (dsRNA) molecules that are complementary to essential genes in Meloidogyne incognita. When the nematodes come into contact with these dsRNA molecules, they trigger the RNAi mechanism within the nematode's cells.

The dsRNA is processed into small interfering RNAs (siRNAs), which then bind to the corresponding mRNA molecules inside the nematode. This binding leads to the degradation of the nematode's mRNA or blocks its translation, effectively silencing the critical genes required for the nematode's survival and reproduction.

As a result of this RNA interference-based approach, the nematode's ability to infest and damage the roots of tobacco plants is diminished or prevented, leading to increased crop yield and protection against infestation. Therefore, the strategy was successfully implemented in tobacco plants to enhance their resistance against the nematode Meloidogyne incognita.