title: Crosstalk between ABA and auxin signaling pathways in roots of Arabidopsis thaliana (L.) Heynh.
abstract: Studies of abscisic acid (ABA) and auxin have revealed that these pathways impinge on each other. The Daucus carota (L.) Dc3 promoter: uidA (beta-glucuronidase: GUS) chimaeric reporter (ProDc3:GUS) is induced by ABA, osmoticum, and the auxin indole-3-acetic acid (IAA) in vegetative tissues of transgenic Arabidopsis thaliana (L.) Heynh. Here, we describe the root tissue-specific expression of ProDc3:GUS in the ABA-insensitive-2 (abi2-1), auxin-insensitive-1 (aux1), auxin-resistant-4 (axr4), and rooty (rty1) mutants of Arabidopsis in response to ABA, IAA and synthetic auxins naphthalene acetic acid (NAA), and 2, 4-(dichlorophenoxy) acetic acid. Quantitative analysis of ProDc3:GUS expression showed that the abi2-1 mutant had reduced GUS activity in response to ABA, IAA, or 2, 4-D: , but not to NAA. Similarly, chromogenic staining of ProDc3:GUS activity showed that the aux1 and axr4 mutants gave predictable hypomorphic ProDc3:GUS expression phenotypes in roots treated with IAA or 2, 4-D: , but not the diffusible auxin NAA. Likewise the rty mutant, which accumulates auxin, showed elevated ProDc3:GUS expression in the absence or presence of hormones relative to wild type. Interestingly, the aux1 and axr4 mutants showed a hypomorphic effect on ABA-inducible ProDc3:GUS expression, demonstrating that ABA and IAA signaling pathways interact in roots. Possible mechanisms of crosstalk between ABA and auxin signaling are discussed.
authors.affiliation: Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409-3131, USA. chris.rock@ttu.edu
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Rock
authors.forename: Xin
authors.initials: X
authors.lastname: Sun
mesh_terms: D015084:2,4-Dichlorophenoxyacetic Acid / Q000494:pharmacology; D000040:Abscisic Acid / Q000494:pharmacology*; D017360:Arabidopsis / Q000145:classification* / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D007210:Indoleacetic Acids / Q000494:pharmacology*; D009280:Naphthaleneacetic Acids / Q000494:pharmacology; D010749:Phosphoprotein Phosphatases / Q000235:genetics / Q000378:metabolism; D010937:Plant Growth Regulators / Q000494:pharmacology; D018517:Plant Roots / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic; D015398:Signal Transduction / Q000187:drug effects*
chemical_list: C100794:AUX1 protein, Arabidopsis; D029681:Arabidopsis Proteins; D007210:Indoleacetic Acids; D009280:Naphthaleneacetic Acids; D010937:Plant Growth Regulators; D015084:2,4-Dichlorophenoxyacetic Acid; C034182:1-naphthaleneacetic acid; C030737:indoleacetic acid; D000040:Abscisic Acid; C087434:ABI1 protein, Arabidopsis; C106443:ABI2 protein, Arabidopsis; D010749:Phosphoprotein Phosphatases