Question

Explain two advatanges and two limitations of using PCR to detect genetic modifications of plants.

Answer 1

·PCR stands for Polymerase Chain Reaction where multiple copies of gene of interest is amplified in vitro using two sets of DNA primers and the enzyme DNA polymerase, which are (amplified gene of interest) further can be ligated with a vector for cloning.

·GMP are the plants whose genes have been altered by manipulation.

ADVANTAGES OF USING PCR TO DETECT GMP :

1.       Genetic modifications has made the crops more tolerant to abiotic stresses , like: cold, draught, heat, salinity etc.. Also helping it in reduction of losses on post harvestation. It has increased the efficiency of plants for mineral uses and prevents the early exhaustion of fertility of soil. Food produced from genetically modified crops has high nutritional value and it also has been used to make tailor made plants to supply resources to industries, such as : starch, fuels, pharmaceuticals etc..

2.       It has reduced the dependencies of crops on chemical pesticides. As for example, Bt.cotton.

Ø  The soil bacteria Bacillus thuringinesisproduces crystal proteins called cry proteins, that are toxic to larva of insects; like : tobacco budworm, bettles and mosquitoes.

Ø  The cry proteins exists as inactive pro toxins and gets converted into activated anti toxins when ingested by the insects as the alkaline pH of the gut solubilises the crystals.

Ø  The activated toxins bind to the surface of the epithelial cells of the midgut and create pores.

Ø  This causes swelling and lysis of cells leading to the death of the insects.

Ø  The cry genes encoding these proteins are isolated from the bacterium and incorporated into several crop plants, like : cotton, tomato, corn, rice,  soyabean etc..

Ø  The proteins encoded by the following cry genes control the pest given against them.

                                                         i.            CryIAc and CryIIAb control cotton bollworm.

                                                       ii.            CryIAb controls cotton borer.

                                                      iii.            CryIIIAb controls colarad potato beetle.

                                                     iv.            CryIIIBb controls corn rootworms.

LIMITATIONS :

1.       As aforesaid in the advantages that it reduces the dependancies of crops on chemical pesticides that kills the insect affecting a plant. Unlikely, it can be dangerous to those insects which are profitable to the plant and carry out functions like : pollination and etc.. Insects like butterflies are not dangerous to any plant but new crop genes can be deadly to them.

2.       Subsequent removal of genetically modified crops from the soil leaves unwanted residual substances thtat can remain for a longer period of time that directly affect the environment thus affecting the entire ecosystem and also leaving its impact on the crop diversity.