Functional analysis of a cotton glucuronosyltransferase promoter in transgenic tobaccos

Abstract

The 5' fragment (1 647 bp) of the cotton glucuronosyltransferase gene (GhGlcAT1) was transcriptionally fused to the b-glucuronidase (GUS) gene, and functionally analyzed for important regulatory regions controlling gene expression in transgenic tobacco plants. GUS activity analysis revealed that the full-length promoter drives efficient expression of the GUS gene in the root cap, seed coat, pollen grains and trichomes. Exposure of the transgenic tobacco to various abiotic stresses showed that the promoter was mainly responsive to the sugars (glucose and sucrose) as well as gibberellic acid. Progressive upstream deletion analyses of the promoter showed that the region from -281 to +30 bp is sufficient to drive strong GUS expression in the trichomes of shoot, suggesting that the 311 bp region contains all cis-elements needed for trichome-specific expression. Furthermore, deletion analysis also revealed that the essential cis-element(s) for sucrose induction might be located between -635 and -281 bp. In addition, sequence analysis of the regulatory region indicated several conserved motifs among which some were shared with previously reported seed-specific elements and sugarresponsive elements, while others were related with trichome expression. These findings indicate that a 1 647-bp fragment of the cotton GhGlcAT1 promoter contains specific transcription regulatory elements, and provide clues about the roles of GhGlcAT1 in cotton fiber development. Further analyses of these elements will help to elucidate the molecular mechanisms regulating the expression of the GhGlcAT1 gene during fiber elongation.

Polyploidization Altered Gene Functions in Cotton (Gossypium spp.)

“…In this study, four groups of fiber development genes were identified: first group, ESTs that were generated from fiber cell, investigated by microarray or RT-PCR function profiling, and confirmed enrichment expression during fiber development, including up-regulation and down-regulation genes [18], [48]; second group, individual genes that were not only confirmed by microarray expression, but also were transformed to Arabidopsis or tobacco to verify their function by complementation test [35], [67], [81], [82]; third group, transcription factors, including MYB family, AP2/EREBP family, and GARP-G2-like transcription factors [36], [38]; and last group, genetically mapped fiber-derived EST gene candidates [40], [41], [44]. All four groups of genes were collected from previous publications and their sequences were downloaded based on the accession numbers from NCBI http://www.ncbi.nlm.nih.gov/or collected from dissertation text (Dr. Hassan's dissertation, Texas A&M University library).…”

Trichome specific expression of the tobacco (Nicotiana sylvestris) cembratrien-ol synthase genes is controlled by both activating and repressing cis-regions

“…When introduced in tobacco however, many of these genes show an expression profile which includes trichome cells but is otherwise poorly specific. For example, the promoters from the cotton fiber genes SUS3 (Ruan et al 2009), GhRGP1 , GhGlcAT1 (Wu et al 2007), GhGAL1 also confer expression in vascular tissues, roots, flowers and cotyledons. Other promoters such as the cotton LTP3 (Liu et al 2000;Hsu et al 2005) and LTP6 (Hsu et al 1999) genes show specificity to the whole glandular trichomes of tobacco (Nicotiana tabacum), but do not differentiate between the secreting cells and the cells of the trichome stalk.…”

A brief summary of major advances in cotton functional genomics and molecular breeding studies in China

“…Applying electrophoretic mobility shift assay, Liu JingYuan's group [14] revealed that a transcription factor encoded by a cotton DREB1/CBFlike gene had a specific binding activity with the previously characterized DRE element and DRE-like sequence in the promoter of the dehydration-responsive late embryogenesis-abundant gene LEA D113, suggestive of a role in low temperature, drought and high salinity resistance. They also studied the expression patterns of several cotton genes, including a reversibly glycosylated polypeptide gene and a glucuronosyl transferase gene, in tobacco cells using the β-galactosidase reporter system [15][16][17] .…”