pBR322 + Source of desired DNA + Pvu-I+ Ligase.

For given contents of rDNA technology.  Which selectable marker gene helps in screening of transformants from non-transformants and recombinants from non-recombinants ?

The transformants will contain both ampicillin and tetracycline resistant gene. Therefore, presence of tet^R gene can help to separate transformants from non-transformants.

Now the Pvu I gene is present in the amp^R gene and hence Insertional inactivation of ampicillin resistant gene would help to separate recombinants from non-recombinants.