Premium
Two cis‐ acting elements necessary and sufficient for gibberellin‐upregulated proteinase expression in rice seeds
Author(s) -
Sutoh Keita,
Yamauchi Daisuke
Publication year - 2003
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.2003.01753.x
Subject(s) - aleurone , transactivation , gibberellin , promoter , glutelin , biology , gene , genetically modified rice , storage protein , gene expression , genetics , regulation of gene expression , microbiology and biotechnology , transgene , genetically modified crops
Summary In germinating rice seeds, a cysteine proteinase (REP‐1), synthesized in aleurone‐layer cells, is a key enzyme in the degradation of the major storage protein, glutelin. The expression of the gene for REP‐1 ( Rep1 ) is induced by gibberellins (GAs) and repressed by abscisic acid (ABA). To identify GA‐responsive elements in the Rep1 promoter, we developed a transient expression system in rice aleurone cells. Deletion and point‐mutation analyses indicated that the GA‐response complex was composed of TAACAGA, TAACGTA, and two copies of CAACTC. The two former sequences were identical to GAREs conserved in the promoter of genes for α‐amylase and proteinases in cereals. The latter, termed as CAACTC regulatory elements (CAREs), were novel GAREs. Gain‐of‐function experiments revealed that two pairs of GARE and CARE were necessary and sufficient to confer GA inducibility. The sequences were also required for effective transactivation by the transcription factor OsGAMyb. Four copies of either GARE or CARE showed transactivation neither by OsGAMyb nor by GA induction. CARE and GARE were also found in the promoters of a rice α‐amylase gene, RAmy1A , and a barley proteinase gene, EPB1 , which are expressed in germinating seeds. Mutations of CARE in their promoters caused a loss of GA inducibility and GAMyb transactivation, suggesting that CARE is the regulatory element for GA‐inducible expression of hydrolase genes in the germinating seeds.