Amino acids induce high seed-specific expression driven by a soybean (Glycine max) glycinin seed storage protein...

We characterize GFP expression driven by a soybean glycinin promoter in transgenic soybean. We demonstrate specific amino acid-mediated induction of this promoter in developing soybean seeds in vitro. In plants, gene expression is primarily regulated by promoter regions which are located upstream of gene coding sequences. Promoters allow transcription in certain tissues and respond to environmental stimuli as well as other inductive phenomena. In soybean, seed storage proteins (SSPs) accumulate during seed development and account for most of the monetary and nutritional value of this crop. To better study the regulatory functions of a SSP promoter, we developed a cotyledon culture system where media and media addenda were evaluated for their effects on cotyledon development and promoter activity. Stably transformed soybean events containing a glycinin SSP promoter regulating the green fluorescent protein (GFP) were generated. Promoter activity, as visualized by GFP expression, was only observed in developing in planta seeds and in vitro-cultured isolated embryos and cotyledons from developing seeds when specific media addenda were included. Asparagine, proline, and especially glutamine induced glycinin promoter activity in cultured cotyledons from developing seeds. Other amino acids did not induce the glycinin promoter. Here, we report, for the first time, induction of a reintroduced glycinin SSP promoter by specific amino acids in cotyledon tissues during seed development.