Analysis of the cotton sucrose synthase 3 (Sus3) promoter and first intron in transgenic Arabidopsis

Cotton sucrose synthase 3 (Sus3) plays an important role in the development of cotton fiber. In order to study the regulation of expression of Sus3, a 1705-bp 5′ up-stream fragment including the 151-bp coding region was amplified from upland cotton (Gossypium hirsutum). The results of the GUS assays of the Sus3 promoter in transformed Arabidopsis showed that the promoter directs GUS expression in sink-tissues including trichomes and root hairs. 3′ deletion analysis of different promoter fragments in transgenic Arabidopsis revealed that the first intron of the Sus3 coding region is a negative regulator of gene expression and specifically represses GUS expression in pollen. The intron had the same regulatory functions under the control of the 35S promoter in transgenic Arabidopsis indicating that this intron has an independent regulatory role during gene expression.