title: Functional characterization of Arabidopsis HsfA6a as a heat-shock transcription factor under high salinity and dehydration conditions.
abstract: Although heat-shock transcription factors are well characterized in the heat stress-related pathway, they are poorly understood in other stress responses. Here, we functionally characterized AtHsfA6a in the presence of exogenous abscisic acid (ABA) and under high salinity and dehydration conditions. AtHsfA6a expression under normal conditions is very low, but was highly induced by exogenous ABA, NaCl and drought. Unexpectedly, the levels of AtHsfA6a transcript were not significantly altered under heat and cold stresses. Electrophoretic mobility shift assays and transient transactivation assays indicated that AtHsfA6a is transcriptionally regulated by ABA-responsive element binding factor/ABA-responsive element binding protein, which are key regulators of the ABA signalling pathway. Additionally, fractionation and protoplast transient assays showed that AtHsfA6a was in cytoplasm and nucleus simultaneously; however, under conditions of high salinity the majority of AtHsfA6A was in the nucleus. Furthermore, at both seed germination and seedlings stage, plants overexpressing AtHsfA6a were hypersensitive to ABA and exhibited enhanced tolerance against salt and drought stresses. Finally, the microarray and qRT-PCR analyses revealed that many stress-responsive genes were up-regulated in the plants overexpressing AtHsfA6a. Taken together, the data strongly suggest that AtHsfA6a acts as a transcriptional activator of stress-responsive genes via the ABA-dependent signalling pathway.
authors: Division of Applied Life Sciences (BK21+), Graduate School of Gyeongsang National University, Jinju, 660-701, Korea; Research Center for Biobased Chemistry, Korea Research Institute of Chemical Technology, Deajeon, 305-600, Korea.
authors: Sung Min
authors: SM
authors: Hwang
authors: Dae Won
authors: DW
authors: Kim
authors: Min Seok
authors: MS
authors: Woo
authors: Hyeong Seop
authors: HS
authors: Jeong
authors: Young Sim
authors: YS
authors: Son
authors: Salina
authors: S
authors: Akhter
authors: Gyung Ja
authors: GJ
authors: Choi
authors: Jeong Dong
authors: JD
authors: Bahk
mesh_terms: D000040:Abscisic Acid / Q000494:pharmacology; D000222:Adaptation, Physiological / Q000187:drug effects / Q000235:genetics; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D004269:DNA, Bacterial / Q000235:genetics; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D003681:Dehydration; D055864:Droughts; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D000076249:Heat Shock Transcription Factors; D016254:Mutagenesis, Insertional / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding / Q000187:drug effects / Q000235:genetics; D015203:Reproducibility of Results; D012441:Saccharomyces cerevisiae / Q000166:cytology; D054712:Salinity; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D013347:Subcellular Fractions / Q000187:drug effects / Q000378:metabolism; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation / Q000187:drug effects / Q000235:genetics; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics
chemical_list: D029681:Arabidopsis Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D000076249:Heat Shock Transcription Factors; C000593178:HsfA6a protein, Arabidopsis; C036483:T-DNA; D014157:Transcription Factors; D000040:Abscisic Acid
keywords: ABA-dependent signalling pathway; ABF/AREB proteins; AtHsfA6a; abscisic acid (ABA); drought; transcriptional activator