Expression of the Arabidopsis abi1-1 mutant allele inhibits proteinase inhibitor wound-induction in tomato.
Abscisic acid (ABA) is an essential component in the wound signalling cascade. Increased levels of endogenous ABA were observed after wounding and shown to be a requisite for wound-induced expression of the proteinase inhibitor II genes. We have taken advantage of the dominant character of the Arabidopsis abi1-1 mutation, to investigate whether ABl1 has a function in ABA signalling in response to wounding. Transgenic tomato plants carrying copies of either the wild-type ABI1 or the mutant abi1-1 alleles were obtained and assayed for wound-induction of the pin2 or LAP genes. While normal levels of gene induction were observed in the transgenic ABI1 plants, the abi1-1 transformants displayed a severe wilty phenotype and reduced seed dormancy. Expression of the abi1-1 dominant mutation blocked accumulation of the drought-induced TAS14 and LE25 mRNAs in response to ABA, as well as ABA- and wound-induced expression of the defense-associated pin2 and LAP transcripts. MeJA-induction of the pin2 and LAP mRNAs, on the contrary, was not affected in the abi1-1 transformants. These results indicate that abi1-1 inhibits wound-induced expression of the pin2 and LAP transcripts by blocking ABA-induction of these genes. This implicates ABI1 in wound-signalling and suggests that a common early ABA signalling pathway may function in the responses to wounding and water stress.
Carrera
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Departamento de Genética Molecular, Centro de Investigación y Desarrollo-C.S.I.C., Barcelona, Spain.
Prat
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D000483:Alleles; D017360:Arabidopsis / Q000235:genetics*; D029681:Arabidopsis Proteins; D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D018551:Solanum lycopersicum; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics; D010641:Phenotype; D010749:Phosphoprotein Phosphatases / Q000235:genetics*; D010935:Plant Diseases; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D011480:Protease Inhibitors / Q000378:metabolism*; D015398:Signal Transduction / Q000235:genetics; D015533:Transcriptional Activation; D014162:Transfection
D029681:Arabidopsis Proteins; D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D010940:Plant Proteins; D011480:Protease Inhibitors; C034104:proteinase inhibitor II protein, plant; C087434:ABI1 protein, Arabidopsis; D010749:Phosphoprotein Phosphatases