Gibberellins regulate the abundance of RNAs with sequence similarity to proteinase inhibitors, dioxygenases and dehydrogenases.
In an effort to understand the molecular mechanism of gibberellin (GA) action, we have cloned and performed an initial characterization of three cDNAs (GAD1, 2, and 3) which correspond to RNAs that become less abundant by 2 h after treatment of tomato (Lycopersicon esculentum Mill.) shoot tissue with gibberellic acid (GA3). Treatment with either auxin or ethephon also decreases the abundance of all three of the GAD RNAs. The tomato ethylene-insensitive mutant, Nr, and the GA-deficient mutant, gib1, were used to show that GA or auxin regulation of GAD RNA abundance is not dependent on ethylene sensitivity, and that ethylene or auxin regulation is not dependent on normal levels of gibberellin biosynthesis. Treatment with abscisic acid (ABA) antagonizes the GA-induced suppression of the GAD1 and GAD2 RNAs. GAD1 is similar to type-II wound-inducible plant proteinase inhibitors. Like the well-characterized proteinase inhibitor II (pin II) of tomato, the GAD1 and GAD2 RNAs are wound inducible. Induction of pin II and GAD1 RNA in gib1 was found to require less-severe wounding than was required using wild-type plants or plants doubly mutant for gib1 and sit (the sit mutation causes ABA deficiency). The predicted GAD2 protein sequence is similar to 2-oxoglutarate-dependent dioxygenases while the predicted GAD3 protein sequence is similar to proteins belonging to the nonmetallo-short-chain alcohol-dehydrogenase family, especially the T ASSELSEED2 (TS2) gene of maize and bacterial hydroxysteroid dehydrogenases.
Jacobsen
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SE
Department of Plant Biology, University of Minnesota, St. Paul 55108, USA.
Olszewski
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NE
D000595:Amino Acid Sequence; D001483:Base Sequence; D002478:Cells, Cultured; D017931:DNA Primers; D018076:DNA, Complementary; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000502:physiology*; D005875:Gibberellins / Q000096:biosynthesis / Q000378:metabolism* / Q000494:pharmacology*; D007210:Indoleacetic Acids / Q000494:pharmacology; D018551:Solanum lycopersicum / Q000187:drug effects / Q000378:metabolism*; D008969:Molecular Sequence Data; D009943:Organophosphorus Compounds / Q000494:pharmacology; D010088:Oxidoreductases / Q000096:biosynthesis / Q000235:genetics*; D010105:Oxygenases / Q000096:biosynthesis* / Q000235:genetics; D010937:Plant Growth Regulators / Q000494:pharmacology; D016133:Polymerase Chain Reaction; D011480:Protease Inhibitors / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis*; D018749:RNA, Plant / Q000096:biosynthesis*; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid
D017931:DNA Primers; D018076:DNA, Complementary; D005875:Gibberellins; D007210:Indoleacetic Acids; D009943:Organophosphorus Compounds; D010937:Plant Growth Regulators; D011480:Protease Inhibitors; D012333:RNA, Messenger; D018749:RNA, Plant; C007842:gibberellic acid; D010088:Oxidoreductases; D010105:Oxygenases; C005073:ethephon