Processes and vectors for amplification or expression of nucleic acid sequences of interest in plants

A process of causing amplification and expression of one or more nucleic acid sequences of interest in a plant, plant tissue, plant cell or cell culture, comprising providing a plant cell with at least two precursor vectors designed for and undergoing processing by site-specific recombination between at least two of said precursor vectors in said cell, whereby due to said processing said plant cell is endowed with at least one replicon which provides(s) for said amplification and expression of said one or more nucleic acids sequences of interest from said at least one replicon.