Function Deletion Analysis of Light-induced Gacab Promoter from Gossypium arboreum in Transgenic Tobacco

The 1009 bp promoter sequence of a light-induced gene, cab, has been cloned from the Gossypium arboreum in an earlier study. This gene encodes the chlorophyll a/b binding protein, which belongs to a class of light-inducible proteins. For designing a minimal length light-inducible Gacab promoter, the full-length Gacab P and the 5′ truncations of 197, 504, and 779 bp in length were fused with gus (uid A) gene and ligated into plant expression vectors. All the constructs were transformed into Nicotiana tabacum variety NC89 using Agrobacterium-mediated transformation method. Seeds from the T1 generation of transgenic tobacco were germinated and grown in either light or dark condition. A GUS histochemical assay showed that only the full-length Gacab promoter was light inducible and expressed in a tissue-specific manner. Promoter activities were quantified by GUS quantity analysis, and the promoter fragment from −504 to −1 bp had the highest activity, which was 0.6-fold higher than that of the CaMV35S promoter.