Question

Bt cotton has been produced by

• A. Northern blotting of Bt gene
• B. Cloning of Bt gene
• C. $Insitu$ hybridisation of Bt gene
• D. Southern blotting of Bt gene

Answer 1

The correct option is B Cloning of Bt gene

$Insitu$ hybridisation is the technique to identify the expression of specific mRNA using a complementary probe against that mRNA. However, Bt cotton is not produced by this technique.

Northern blotting is the technique to identify a specific RNA from the pool of RNA present in a cell. It is a hybridisation-based method in which total RNA is isolated and transferred on a nylon membrane. This is followed by the identification of specific RNA by autoradiography using a specific RNA probe. Bt cotton is not produced by northern blotting of the Bt gene.

Cloning is the process to make replicas or clones of recombinant DNA. Bt cotton is produced by cloning. Initially,
'$cry$' gene is isolated from the bacterium, $Bacillusthuringiensis$. This is then incorporated into the cotton plant (host cell) by using suitable vectors.

The host cell containing the recombinant DNA with the $cry$ gene replicates and creates copies in daughter cells. Thus, cloning of the Bt gene produced Bt cotton.

Southern blotting is the technique to identify a specific DNA sequence. It is also based on a hybridisation method in which a complementary DNA probe binds to the specific DNA sequence for its identification.

Hence the correct option is
c. Cloning of Bt gene