Arabidopsis mutants deregulated in RCI2A expression reveal new signaling pathways in abiotic stress responses.
To uncover new pathways involved in low-temperature signal transduction, we screened for mutants altered in cold-induced expression of RCI2A, an Arabidopsis gene that is not a member of the CBF/DREB1 regulon and is induced not only by low temperature but also by abscisic acid (ABA), dehydration (DH) and NaCl. This was accomplished by generating a line of Arabidopsis carrying a transgene consisting of the RCI2A promoter fused to the firefly luciferase coding sequence. A number of mutants showing low or high RCI2A expression in response to low temperature were identified. These mutants also displayed deregulated RCI2A expression in response to ABA, DH or NaCl. Interestingly, however, they were not altered in stress-induced expression of RD29A, a CBF/DREB1-target gene, suggesting that the mutations affect signaling intermediates of CBF/DREB1-independent regulatory pathways. Several mutants showed alterations in their tolerance to freezing, DH or salt stress, as well as in their ABA sensitivity, which indicates that the signaling intermediates defined by the corresponding mutations play an important role in Arabidopsis tolerance to abiotic stresses. Based on the mutants identified, we discuss the involvement of CBF/DREB1-independent pathways in modulating stress signaling.
Medina
Joaquín
J
Departamento de Biotecnología, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Carretera de la Coruña, Km. 7, 28040 Madrid, Spain.
Rodríguez-Franco
Marta
M
Peñalosa
Andrés
A
Carrascosa
María J
MJ
Neuhaus
Gunther
G
Salinas
Julio
J
D000040:Abscisic Acid / Q000502:physiology; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D003080:Cold Temperature; D018506:Gene Expression Regulation, Plant / Q000502:physiology*; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D010641:Phenotype; D030821:Plants, Genetically Modified; D015398:Signal Transduction / Q000502:physiology*; D012965:Sodium Chloride; D014867:Water / Q000378:metabolism
D029681:Arabidopsis Proteins; D006360:Heat-Shock Proteins; D008565:Membrane Proteins; C108982:RCI2A protein, Arabidopsis; D014867:Water; D012965:Sodium Chloride; D000040:Abscisic Acid