Abstract Current biotechnology research is focused on tissue-specific expression of genes of interest in plants. Promoters with specific spatial and temporal expression profiles in targeted organisms are in wide use for this. This study investigated whether the Arabidopsis thaliana seed- and pollen-specific promoter MXL maintains its specificity in transgenic tobacco plants. Histochemical analysis revealed that the MXL fusion promoter drives slightly different GUS expression in that heterologous organism. GUS staining was clearly detected in the bicellular stage of pollen development and later in germinating tobacco pollen grains. Unlike in A. thaliana, where the MXL promoter is active during the whole period of embryo development, in tobacco its activity was restricted to a short temporal and spatial window from late-heart to mid-torpedo stages, mainly in the apical part of the developing embryo. These results point to the need to test the expression profiles of heterologous promoters in targeted species before they are used in particular biotechnological programs.