Explain with the help of one example how genetically modified plants can:

(a) Reduce usage of chemical pesticides

(b) Enhance nutritional value of food crops

(a) A nematode Meloidogyne incognita is known to cause root rot in tobacco plant

- Initially nematocides were used to deal with this nematode.

- But later on, the scientists modified the tobacco crop and adopted a method to kill the nematode called the RNA interference (RNAi).

- In the RNAi mechanism, scientist introduced a host specific double standard DNA using Agrobacterium tumefaciens.

- The DNA had both sense & antisense sequences so, that when transcription happen complementary RNA strands of both sense & antisense strands are produced.

- Both RNA strands being complementary forms double strands & gets chop-off since RNA of nematode gets inactivate.

(b) Golden rice is the example of genetically modified crops.

- β-carotene gene from daffodil plant was introduced into the rice plant, in order to nutritionally enrich it with vitamin A.

- β-carotene is the precursor of vitamin A.