Identification of tobacco ANGUSTIFOLIA (AN) gene promoter activity
Narrower and thicker upper leaves of tobacco (Nicotiana tabacum) are the primary cause of its lower usability in southwest China. The ANGUSTIFOLIA (AN) gene controls the polar elongation of leaf cells in leaf width direction and the trichome-branching pattern in the plant. The tobacco K326 AN gene (NtAN) originated from diploid species N. tomentosiformis (NtAN-T) cloned in our previous study. The promoter activity of the NtAN-T gene was studied in this report. Firstly, the possible transcriptional regulation sites of the NtAN-T gene promoter sequence, which we had cloned 2779bp in our previous experiment, were analysed by bioinformatics analysis. Many light responsive regulatory sites (such as AE-box, ATCT-motif, Box 4, Box I, G-Box, GAG-motif, Gap-box, I-box and TCCC-motif), hormonal response regulatory site (such as TGA-element) and environmental stress reactions sites (such as TCA-element, ABRE, TC-rich repeats and CGTCA-motif) were found in this promoter sequence. Secondly, the full-length sequence of the NtAN-T gene promoter was cloned into the plant expression vector pCAMBIA 1301, the recombinant expression vector was then transferred into tobacco K326 sterile seedling leaf, and positive transgenic plantlets were detected; twelve positive transgenic plantlets were confirmed. These study results will provide the experimental basis for further study of the function of this promoter and for the control of NtAN-T gene expression.