The present invention relates to a method for excising a nucleic acid
sequence from the genome of a plant or a plant cell. This method is based
on the steps of transforming a plant cell with a construct encoding a DNA
double strand break inducing enzyme (DSBI), generating a transgenic plant
line, performing a transient assay to analyze the functionality of the
transgenic enzyme, crossing the plant line with a line containing a
nucleic acid sequence to be excised and performing an immature embryo
conversion or a tissue culture regeneration through callus formation. The
method can also be reversed, which means that a plant cell is transformed
with a construct encoding a nucleic acid sequence to be excised, and the
crossing is performed with a plant line containing a DSBI. As an
alternative to the crossing step, a re-transformation of a transgenic
plant line with a second construct can also be performed. The invention
is also directed to a plant obtained by this method, or progeny,
propagation material, part, tissue, cell or cell culture, derived from
such a plant. Finally, the invention relates to the use of a plant or
progeny, propagation material, part, tissue, cell or cell culture,
derived from this method, as aliment, fodder or seeds or for the
production of pharmaceuticals or chemicals.