Isolation and Characterization of a Novel Seed-Specific Promoter from Malaytea Scurfpea

摘要

Psc-AFP, an antifungal protein with trypsin inhibitor activity, was isolated from a traditional Chinese herb, malaytea scurfpea (Psoralea corylifolia L.); the protein was found to be preferentially expressed in seeds. A 737-bp upstream sequence from the ATG initiation codon site of the gene encoding this protein was isolated using a chromosomal walking method and identified as pPsc-AFP. The analysis of the cis-acting elements in PlantCARE database indicated that pPsc-AFP contains RY elements and GCN4 motifs, a kind of seed-specific elements, and a Skn-1 motif. The features of this fragment were studied by fusing it into the upstream region of the beta-glucuronidase (GUS) reporter gene and transforming the recombinant expression vector pBI121-pPsc-AFP::GUS into tobacco by using the leaf disk method. The expression pattern was determined using GUS histochemical staining. The fragment showed a strong GUS activity in seeds, whereas its expression level was considerably lower in other organs such as the roots, stems, and reproductive organs, including stamens and pistil, indicating that pPsc-AFP was able to direct GUS expression in a seed-specific manner in transgenic tobacco.