Histochemical map of the ectopic expression of the Arabidopsis atExt1 extensin gene in transgenic tobacco

Abstract

ABSTRACT. Histochemical analysis of transgenic tobacco plants harboring the promoter of the Arabidopsis extensin gene atExt1 fused to the β-glucuronidase gene coding sequence demonstrated expression of the transgene in stem tissues. The transgene was expressed in cells of the internal and external phloem at the nodal and internodal regions of the older parts of mature stems. In younger parts of the same stem, expression of the transgene was slightly modified: expression was detected in the internal phloem in the internodal areas. In the nodal areas, the phloem tissue and the surrounding parenchyma were stained, demonstrating transgene expression. Expression was also seen in the phloem of the inflorescence; it was non-specific at the junctions of the flowers to the inflorescence. β-glucuronidase (reporter gene) staining was also observed in the pollen grains and at the base of the corolla.

Identification of promoter regions in the Arabidopsis thaliana atExt1 extensin gene controlling late responses to wounding and pathogen attack

“…Analysis of the atExt1 promoter sequence by Merkouropoulos (2000) allowed the design of seven promoter truncations, the size and range of which were based on the identification and location of putative cis-elements in the 5' flanking promoter region. Elements given the most attention were those considered to be responsible for induction by stress.…”

“…The atExt1 gene is the best studied and characterised Arabidopsis extensin gene (Merkouropoulos 2000, Merkouropoulos et al 1999, Merkouropoulos and Shirsat 2003, Roberts and Shirsat 2006, Wei and Shirsat 2006. This gene, which has been analysed extensively in the present study, has an unusual coding region in which Ser(Pro) 4 motifs alternate regularly with Ser(Pro) 3 motifs, reflecting an extraordinary molecular flexibility in the tertiary protein structure (Lamport 2001).…”