The promoter of soybean photoreceptor GmPLP1 gene enhances gene expression under plant growth regulator and light stresses

To reveal the molecular mechanism underlying the expression of soybean PLP1 (GmPLP1) gene that contains PAS/LOV domain, its 5′ regulatory region was analyzed. The 1.5 kbp fragment upstream of the GmPLP1 gene was isolated from soybean cultivar ‘Dongnong L13’ by genome walking. There were 107 cis-acting elements in the promoter predicted by online software Plant CARE and PLACE. The possible transcription start site (TSS) was confirmed by RACE (rapid-amplification of cDNA ends) and the promoter fragment deletions were inserted into the 5′ region of the gusA reporter gene in vector pBI121 (replacing the 35S promoter). In order to determine the promoter characteristic of GmPLP1, The constructs were transferred into Nicotiana tabacum and Glycine max. The GUS activity was up-regulated under dark, blue light, gibberellin A3 and abscisic acid driven by GmPLP1 promoter. The highest GUS enzyme activity was analyzed in transgenic plants at seedling and seed developmental stages. The high GUS enzyme level was detected in the leaves of tobacco and soybean seedlings, as well in seed formation when the full sequence of the promoter was present. The promoter activities decreased along with the plant being close to maturity. These results provided evidence of the developmental regulation of the GmPLP1 promoter in seedlings and developing seeds.