Arabidopsis Cys2/His2-Type Zinc-Finger Proteins Function as Transcription Repressors under Drought, Cold, and High-Salinity Stress Conditions

Abstract

ZPT2-related proteins that have two canonical Cys-2/His-2-type zinc-finger motifs in their molecules are members of a family of plant transcription factors. To characterize the role of this type of protein, we analyzed the function of Arabidopsis L. Heynh. genes encoding four different ZPT2-related proteins (AZF1, AZF2, AZF3, and STZ). Gel-shift analysis showed that the AZFs and STZ bind to A(G/C)T repeats within an EP2 sequence, known as a target sequence of some petunia (Petunia hybrida) ZPT2 proteins. Transient expression analysis using synthetic green fluorescent protein fusion genes indicated that the AZFs and STZ are preferentially localized to the nucleus. These four ZPT2-related proteins were shown to act as transcriptional repressors that down-regulate the transactivation activity of other transcription factors. RNA gel-blot analysis showed that expression of AZF2 and STZ was strongly induced by dehydration, high-salt and cold stresses, and abscisic acid treatment. Histochemical analysis of b-glucuronidase activities driven by the AZF2 or STZ promoters revealed that both genes are induced in leaves rather than roots of rosette plants by the stresses. Transgenic Arabidopsis overexpressing STZ showed growth retardation and tolerance to drought stress. These results suggest that AZF2 and STZ function as transcriptional repressors to increase stress tolerance following growth retardation.Drought, high salinity, and low temperature are adverse environmental conditions that limit the growth of plants. Plants respond and adapt to these stresses in order to survive. These stresses induce various biochemical and physiological changes, including growth inhibition, to acquire stress tolerance. A number of genes have been described that respond to stresses at the transcriptional level (Ingram and

Mapping methyl jasmonate-mediated transcriptional reprogramming of metabolism and cell cycle progression in cultured Arabidopsis cells

“…The repressors were encoded by STZ/ZAT10 and AZF2. These closely related C2H2 Zn finger proteins contain an ERF-associated amphiphilic repression domain and might act as both positive and negative regulators of plant defenses (24,34). These findings are summarized in a model (Fig.…”

The EAR-motif of the Cys2/His2-type Zinc Finger Protein Zat7 Plays a Key Role in the Defense Response of Arabidopsis to Salinity Stress

“…It was shown to contain a functional EAR-motif and to suppress the transcription of different reporter and defense genes (5,11,12). Constitutive expression of Zat10 was found to result in growth suppression and enhanced tolerance of plants to drought stress, osmotic stress, and salinity (12,13). Interestingly, Zat10 loss-of-function lines are also more tolerant to osmotic and salinity stress, suggesting that Zat10 plays a dual role in modulating the defense response of plants to abiotic stresses (13).…”

“…Zat10 was initially identified as a salt-, drought-, and cold-response protein (10). It was shown to contain a functional EAR-motif and to suppress the transcription of different reporter and defense genes (5,11,12). Constitutive expression of Zat10 was found to result in growth suppression and enhanced tolerance of plants to drought stress, osmotic stress, and salinity (12,13).…”

“…Although different Zat proteins were shown to suppress the transcription of reporter and defense genes (5,11,12), it is not clear whether the EAR-motif of these proteins is involved in this function (1). In addition, it is not clear whether the enhanced tolerance of transgenic plants expressing different Zat proteins to abiotic stresses is mediated by the EAR-motif, and whether or not growth suppression observed in some of these plants is also a result of transcriptional repression by the EAR-motif.…”

Dual function of an Arabidopsis transcription factor DREB2A in water-stress-responsive and heat-stress-responsive gene expression

“…Many of their protein products, such as RNA-binding proteins, sugar transport proteins, desaturases, late embryogenesis-abundant (LEA) proteins, and osmoprotectant biosynthesis-proteins, are known to function against stresses (4) and are probably responsible for the stress tolerance of the transgenic plants. Transcription factors were also downstream targets, which suggests the existence of further regulation of gene expression downstream of the DRE͞DREB regulon (16)(17)(18). Conserved sequences in the promoter regions of the genes directly downstream of DREB1A were analyzed, and A͞GCCGACNT was found in their promoter regions between Ϫ51 and Ϫ450 as a consensus DRE (16).…”