Utilization of luciferase fusion genes to monitor differential regulation of phytohemagglutinin and phaseolin promoters in transgenic tobacco
The firefly luciferase gene can be used as a very sensitive and easily assayed reporter to study promoter activity in transgenic plants. To study the regulation of the promoters of the genes for phytohemagglutinin-L and β-phaseolin, two seed storage proteins of the common bean, Phaseolus vulgaris, we constructed chimeric genes consisting of their 5′ flanking regions and the luciferase gene, and introduced the constructs into tobacco via Agrobacterium-mediated transformation. Our studies indicate that the two seed protein promoters are activated during seed development, and luciferase accumulates until seed maturation. Little or no luciferase activity could be found in other plant organs, and activity rapidly declined during seedling growth. The construct driven by the phaseolin promoter gave rise to about eight times more luciferase than the one driven by the phytohemagglutinin promoter. Thus, in addition to proper temporal and spatial regulation of promoter activity, we found that the differences in the levels of luciferase driven by the two promoters were similar to the calculated differences in the levels of protein in the bean resulting from the activities of these promoters. However, both promoters gave rise to similar levels of luciferase mRNA in the seeds of the transgenic plants. These results show that the levels of luciferase activity reflect not only the strength of the promoter but also the stability and/or translatability of the mRNA.
Riggs, C. D.,
Hunt, D. C.,
Chrispeels, M. J.
Utilization of luciferase fusion genes to monitor differential regulation of phytohemagglutinin and phaseolin promoters in transgenic tobacco.
Plant Science, 63(1), 47–57.