What is the likely basis of the novel strategy used to prevent Meloidogyne incognita infection in tobacco plants?

RNA interference (RNAi)

The correct answer is Option (2) - RNA interference (RNAi)

(2) RNA interference.

Explanation:

(1) DNA interference: DNA interference typically refers to techniques that target and manipulate specific genes at the DNA level. It can involve gene editing methods which allows scientists to modify or disrupt specific DNA sequences. While this approach can be used to alter genes in plants to make them resistant to certain pathogens, it is not commonly associated with preventing nematode infections in plants.

(2) RNA interference (RNAi): A novel strategy was implemented to prevent the infestation of tobacco plants by the nematode Meloidogyne incognita, which is known to cause significant reductions in yield. This strategy was based on a natural cellular defense mechanism called RNA interference (RNAi), which occurs in all eukaryotic organisms, including plants and animals.

RNAi involves the silencing of specific mRNA molecules by using complementary double-stranded RNA (dsRNA) molecules. These dsRNA molecules bind to the target mRNA and prevent its translation, effectively silencing the gene's expression. The complementary RNA used in this strategy can be obtained from various sources, such as infections by viruses with RNA genomes or mobile genetic elements (transposons) that replicate through an RNA intermediate.

By introducing synthetic dsRNA molecules that target essential genes in Meloidogyne incognita, the nematode's ability to infest tobacco plant roots is disrupted. As a result, the nematodes are unable to cause damage to the tobacco plants, leading to improved crop yield and protection against infestation.

This RNA interference-based approach provides a targeted and environmentally friendly method to combat nematode infestations, which are known to parasitize a wide range of plants and animals, including humans.

 (3) RNA initiation: "RNA initiation" is not a well-known term in the context of genetic manipulation or plant protection. It is not a commonly used strategy to prevent nematode infections in plants.

(4) DNA initiation: "DNA initiation" is also not a well-defined term in this context. It doesn't seem to be a relevant strategy for preventing nematode infections in tobacco plants.

Therefore, the most likely option is (b) RNA interference, as RNAi has been successfully used to silence genes in nematodes, rendering them less harmful or preventing their infection in plants.