Characterisation of BRH1, a brassinosteroid-responsive RING-H2 gene from Arabidopsis thaliana.
Although many important aspects of plant development are controlled by brassinosteroids (BRs), the early molecular events of their hormonal action are largely unknown. Using a differential-display RT-PCR screen designed to detect early response transcripts, those regulated by BR treatment in the absence of de novo protein synthesis, we identified an Arabidopsis thaliana (L.) Heynh. gene (designated BRH1) that encodes a novel RING finger protein. As deduced from a complete cDNA clone, the 170-amino-acid sequence of BRH1 forms an N-terminal hydrophobic domain and a C-terminal RING-H2 signature. In wild-type Arabidopsis, the level of the BRH1 transcript was rapidly down-regulated by brassinolide, but this effect was abolished in a BR-insensitive mutant deficient in the BRI1 receptor. BRH1 mRNA abundance was not influenced by other phytohormones, but the pathogen elicitor chitin induced a rapid and transient accumulation of the transcript. Antisense expression of BRH1 resulted in transgenic Arabidopsis plants with thicker inflorescence stems and altered leaf morphology, whereas in sense overexpression lines no phenotypic effect could be observed. Considering the potential of the RING proteins to participate in regulatory protein complexes, BR-dependent expression of BRH1 may suggest its involvement in later hormonal effects.
Molnár
Gergely
G
Institute of Plant Biology, Biological Research Center of the Hungarian Academy of Sciences, P.O. Box 521, 6701 Szeged, Hungary.
Bancoş
Simona
S
Nagy
Ferenc
F
Szekeres
Miklós
M
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000235:genetics*; D015152:Blotting, Northern; D060406:Brassinosteroids; D002352:Carrier Proteins / Q000235:genetics*; D002686:Chitin / Q000494:pharmacology; D002777:Cholestanols / Q000494:pharmacology; D018076:DNA, Complementary / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D010802:Phylogeny; D010840:Phytosterols / Q000494:pharmacology; D030821:Plants, Genetically Modified; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013260:Steroids, Heterocyclic / Q000494:pharmacology; D016335:Zinc Fingers / Q000235:genetics
D029681:Arabidopsis Proteins; C463980:BRH1 protein, Arabidopsis; D060406:Brassinosteroids; D002352:Carrier Proteins; D002777:Cholestanols; D018076:DNA, Complementary; D010840:Phytosterols; D012333:RNA, Messenger; D013260:Steroids, Heterocyclic; D002686:Chitin; C023623:brassinolide