Analysis of the Cotton E6 Promoter

An E6 gene from sea island cotton (Gossypium barbadense) was expressed specifically in cotton fiber cells to transfer functions to cultivated species for better transgenic engineering. The regulatory activity of the E6 promoter region was then studied by isolating a 614-bp fragment of the 5'-flanking region from upland cotton (Gossypium hirsutum CRI-12) to produce a green fluorescent protein (GFP) reporter construct for analysis of tissue-specific expression in transgenic tobacco seedlings. Fluorescent analyses indicate that the relatively short E6 promoter is sufficient to direct green fluorescent protein expression specifically in the leaf trichomes (hair cells) of the transgenic tobacco plants. As cotton fibers are also unicellular trichomes that differentiate from epidermal cells of developing cotton ovules, the result suggests that the relatively short E6 promoter can serve as a fiber-specific expression promoter for genetic engineering to improve cotton fiber quality.