ABSTRACT
The jasmonic acid (JA)-responsive gene RERJ1 isolated from suspension-cultured rice cells encodes a transcription factor with a basic helix-loop-helix motif. In this study, we found that RERJ1 is also expressed in rice plants in response to JA, and that its expression in rice leaves is up-regulated by exposure to wounding and drought stress. It is also suggested that JA but not abscisic acid is involved in the up-regulation of RERJ1 expression caused by wounding and drought stress.
Subject(s)
DNA-Binding Proteins/metabolism , Oryza/metabolism , Transcription Factors/metabolism , Abscisic Acid/metabolism , Basic Helix-Loop-Helix Transcription Factors , Cyclopentanes/metabolism , Gene Expression Regulation, Plant/physiology , Helix-Loop-Helix Motifs , Oxylipins , Plant Growth Regulators/physiology , Plant Leaves/metabolism , Plant Proteins , Plant Roots/metabolism , Up-Regulation , WaterABSTRACT
Differential screening of a cDNA library constructed using poly(A)(+) RNA from suspension-cultured rice cells treated with jasmonic acid (JA) for 1/2h yielded a cDNA of a gene tentatively named RERJ1 that is upregulated in response to exogenous JA. Northern blot analysis indicated that the RERJ1 mRNA levels peaked at 1/2-1h after the addition of jasmonic acid and then decreased gradually. RERJ1 encodes a transcriptional regulator with a basic helix-loop-helix motif. The phenotypes of transgenic rice plants overexpressing sense or antisense RERJ1 mRNA demonstrated that RERJ1 is involved in the growth inhibition of rice shoots caused by JA. Other biological functions of RERJ1 are discussed from an evolutionary standpoint.
Subject(s)
DNA-Binding Proteins/physiology , Helix-Loop-Helix Motifs/physiology , Oryza/physiology , Plant Shoots/physiology , Transcription Factors/metabolism , Transcription Factors/physiology , Amino Acid Sequence , Basic Helix-Loop-Helix Transcription Factors , Cells, Cultured , DNA-Binding Proteins/chemistry , Dose-Response Relationship, Drug , Gene Expression Regulation, Plant/drug effects , Gene Expression Regulation, Plant/physiology , Molecular Sequence Data , Oryza/drug effects , Plant Proteins , Plant Shoots/drug effects , Plants, Genetically Modified/drug effects , Plants, Genetically Modified/physiology , Recombinant Proteins/chemistry , Recombinant Proteins/metabolism , Sequence Homology, Amino Acid , Transcription Factors/chemistry , Up-Regulation/drug effects , Up-Regulation/physiologyABSTRACT
In suspension-cultured rice ( Oryza sativaL.) cells, jasmonic acid (JA) functions as a signal transducer in elicitor N-acetylchitoheptaose-induced phytoalexin production. Differential screening of a cDNA library constructed using poly(A)(+) RNA from suspension-cultured rice cells treated with JA (10(-4) M) for 2 h yielded a cDNA for a gene that responded to exogenous JA by an increase in mRNA level. Nucleotide sequence analysis indicated that the cDNA encodes an homologue of the yeast Old Yellow Enzyme. The deduced amino acid sequence was very similar to the sequences of 12-oxophytodienoic acid reductases (OPR) 1 and 2 from Arabidopsis thaliana(AtOPR1 and AtOPR2) and OPR1 from tomato ( Lycopersicon esculentum) (LeOPR1). The cDNA-encoded protein purified from recombinant Escherichia coli cells as a hexahistidine-tagged fusion protein exhibited OPR activity similar to that of AtOPR1, AtOPR2, and LeOPR1, which catalyze reduction of (-)- cis-12-oxophytodienoic acid (OPDA) preferentially over (+)- cis-OPDA, a natural precursor of JA. Thus the rice enzyme was termed OsOPR1. The physiological roles of OsOPR1 are discussed. This is the first report of the cloning of an OPR gene from a monocot plant.
Subject(s)
Cyclopentanes/pharmacology , Oryza/genetics , Oxidoreductases Acting on CH-CH Group Donors , Oxidoreductases/genetics , Plant Growth Regulators/pharmacology , Cells, Cultured , Cloning, Molecular , Cycloheximide/pharmacology , DNA, Complementary/chemistry , DNA, Complementary/genetics , Fatty Acids, Unsaturated/pharmacology , Gene Expression Regulation, Enzymologic/drug effects , Gene Expression Regulation, Plant/drug effects , Molecular Sequence Data , Oryza/cytology , Oryza/drug effects , Oxidoreductases/metabolism , Oxylipins , Phylogeny , Plant Proteins/genetics , Plant Proteins/metabolism , RNA, Messenger/drug effects , RNA, Messenger/genetics , RNA, Messenger/metabolism , Sequence Analysis, DNAABSTRACT
Two cDNA clones for jasmonic acid (JA)-responsive genes, RRJ1 and RRJ2, were isolated by differential screening from suspension-cultured rice cells treated with JA for 2 h. The putative RRJ1 protein is completely identical to that of a putative rice cystathionine gamma-lyase, while the putative RRJ2 protein is highly similar in sequence to a rice pyruvate decarboxylase, PDC1.
