Tobacco plants, resistant to a nematode, have been developed by the introduction of DNA that produces (in the host cells):

Explanation

Many nematodes live in plants and animals including human beings. a nematode Meloidogyne incognita infects tobacco plants and causes a great reduction in yield. A novel strategy was adopted to prevent this infection that was based on the process of RNA interference. RNA interference is the phenomenon of inhibiting the activity of a gene by the synthesis of RNA molecules complementary to the mRNA. The normal messenger RNA of a gene is said to be 'sense' because it carries the codon that is 'read' during translation. Normally the complement to the mRNA 'sense' strand will not contain a sequence of codons that can be translated to produce a functional protein thus this complementary stand is called antisense RNA. The antisense RNA and messenger RNA molecules will anneal to form duplex RNA molecules and the duplex RNA molecules cannot be translated. Thus the presence of antisense RNA will block the translation of the Messenger RNA of the affected gene. Recent evidence indicates that these RNA duplexes are often rapidly degraded in Vivo.