Patent ID: 7572634

Claim:
A method for locating preferred integration sites within a genome of a plant cell, said method comprising a) stably integrating into the genome of the plant cell a target site comprising a first nucleotide sequence operably linked to a promoter wherein said target site is flanked by a first recombination site and a second recombination site and wherein said first and said second recombination sites are non-identical; b) locating the preferred integration site by selecting the plant cell expressing said first nucleotide sequence; c) introducing into the plant cell expressing said first nucleotide sequence a transfer cassette, said transfer cassette comprising a nucleotide sequence of interest flanked by the first and the second recombination sites; and, d) providing a recombinase that recognizes and implements recombination at the first and the second recombination sites, wherein said preferred integration site does not disrupt expression of an essential sequence and provides for adequate expression of said first nucleotide sequence.