Rice salT promoter is activated in Papaver somniferum and Nicotiana tabacum transgenic cells in the absence of exogenous ABA

With the aim of modifying secondary metabolism in Opium poppy (Papaver somn iferum) and tobacco (Nicotiana tabacum) cells, gene transfer was performed using the sam1 gene from Arabidopsis thaliana under the control of the salT promoter, This promoter is induced by ABA in rice and in tobacco and we ha ve shown that it is also induced in poppy cells (gus gene). Putatively tran sformed poppy and tobacco cell lines with the sam1 gene were obtained. In t he absence of exogenous inducer we noticed the expression of the transgene resulting in a significant increase of SAM-S activity in all tested transfo rmants of poppy and in half the transgenic tobacco cell lines tested. Addit ion of ABA to the culture medium failed to enhance the expression of the tr ansgene in both species and resulted in a decrease of the sam1 gene express ion in some cell lines. Since the salT promoter is induced by exogenous ABA in both species (gus reporter gene), we suggest a partial sam1 transgene i nactivation in certain cell lines. These results show that the efficiency o f a regulatory sequence may be different when fused with a reporter gene (g us) compared to fusion with a gene belonging to the housekeeping family (sa m1). (C) 2001 Elsevier Science Inc. All rights reserved.