Evaluation of the expression level of the endogenous marker poUBI gene for studies on transgene stability in bar and StSy GM poplars

This work reports on the isolation and molecular characterization of the poUBI cDNA encoding polyubiquitin from white poplar (Populus alba L. cv ‘Villafranca’). Expression analysis was performed on different poplar organs and tissues, at different developmental stages and in relation to the growth/dormancy cycle. Information concerning the steady-state level of poUBI transcripts in planta are required to better evaluate the possible use of this gene as endogenous marker for studies on long-term transgene stability in genetically modified white poplars.