Submitted to: International Congress of Plant Molecular Biology
Publication Type: Abstract only
Publication Acceptance Date: 2/20/2003
Publication Date: 5/23/2003
Citation: Federico, M.L., Kaeppler, H.F., Skadsen, R.W. 2003. Comprehensive mutant analysis of the barley ltp6 gene promoter. Proceedings of 7th International Congress of Plant Molecular Biology. p. 79. Interpretive Summary:
Technical Abstract: Differential display was used to identify a transcript that was highly expressed in the pericarp epidermis but not in leaves of barley. The sequence and its promoter were cloned. The ORF encoded a polypeptide of 124 amino acids showing 87% identity with WBP1A, a wheat lipid transfer protein (LTP) homologue, but much lower homology with barley LTPs. This Ltp-like gene is also highly expressed in coleoptiles and embryos. Southern blots showed that it exists as a single copy in barley. mRNA levels increase during salt and cold treatment and under exogenously applied abscisic acid and salicylic acid in seedlings. The tissue-specific and response pattern of Ltp6 is distinct from other barley Ltp genes. A comprehensive mutant analysis of the promoter was performed using sgfp as a reporter gene in transient expression experiments. Real-time PCR was used to assess the level of transcription conferred by the different promoter constructs. Promoter deletion analysis showed that 246 bp of proximal upstream sequence confers tissue-specific expression and retains most of the promoter activity. A substitution mutant analysis performed in this region, which contains several previously identified motifs associated with abscisic acid responses, showed that substitution of a novel MYC binding site abolishes most of the promoter activity. The involvement of 3 MYB binding sites in the combinatorial control of Ltp6 transcription is under investigation. These studies may define determinants of tissue-specific and stress-related gene responses.