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Differential in vitro DNA binding activity to a promoter element of the gn1 β‐1,3‐glucanase gene in hypersensitively reacting tobacco plants
Author(s) -
Alonso Elena,
Niebel Fernanda,
Obregón Patricia,
Gheysen Godelieve,
Inzé Dirk,
Montagu Marc,
Castresana Carmen
Publication year - 1995
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1046/j.1365-313x.1995.7020309.x
Subject(s) - pseudomonas syringae , gene , promoter , biology , electrophoretic mobility shift assay , microbiology and biotechnology , transgene , regulatory sequence , gene expression , reporter gene , dna , genetics
Summary In a hypersensitive reaction to pathogen infection, expression of the β‐1,3‐glucanase gn1 gene is induced in cells surrounding the necrotic lesions. The 5′‐flanking sequence of gn1 was examined to investigate the molecular basis controlling activation of gene expression during this plant defense response. Studies on transgenic tobacco plants containing gn1 promoter deletions fused to the β‐glucuronidase reporter gene revealed the presence of negative and positive regulatory sequences mediating both the level and the spatial distribution of gn1 expression. Promoter sequences to −138 bp were sufficient to confer increased gene expression around the necrotic lesions produced in response to Pseudomonas syringae pv. syringae inoculation. It is demonstrated by electrophoretic mobility shift assays that nuclear proteins in both healthy and hypersensitively reacting tobacco leaves interact with DNA sequences within the regulatory elements identified. Among the binding sequences characterized, the promoter region extending from −250 to −217 bp contained the DNA motif ‐GGCGGC‐ found to be conserved in most if not all promoters of genes encoding pathogenesis‐related basic proteins. The activity bound by this promoter sequence was stronger in hypersensitively responding tissues than in healthy untreated tobacco leaves.