Abstract
Cys2/His2-type zinc finger proteins, which contain the EAR transcriptional repressor domain, are thought to play a key role in regulating the defense response of plants to biotic and abiotic stress conditions. Although constitutive expression of several of these proteins was shown to enhance the tolerance of transgenic plants to abiotic stress, it is not clear whether the EAR-motif of these proteins is involved in this function. In addition, it is not clear whether suppression of plant growth, induced in transgenic plants by different Cys2/His2 EAR-containing proteins, is mediated by the EAR-domain. Here we report that transgenic Arabidopsis plants constitutively expressing the Cys2/His2 zinc finger protein Zat7 have suppressed growth and are more tolerant to salinity stress. A deletion or a mutation of the EAR-motif of Zat7 abolishes salinity tolerance without affecting growth suppression. These results demonstrate that the EAR-motif of Zat7 is directly involved in enhancing the tolerance of transgenic plants to salinity stress. In contrast, the EAR-motif appears not to be involved in suppressing the growth of transgenic plants. Further analysis of Zat7 using RNAi lines suggests that Zat7 functions in Arabidopsis to suppress a repressor of defense responses. A yeast two-hybrid analysis identified putative interactors of Zat7 and the EAR-domain, including WRKY70 and HASTY, a protein involved in miRNA transport. Our findings demonstrate that the EAR-domain of Cys2/His2-type zinc finger proteins plays a key role in the defense response of Arabidopsis to abiotic stresses.
Highlights
Mental programs under control they are thought to prevent excessive waste of resources and the activation of programmed cell death caused by metabolic imbalances or runaway response pathways [1,2,3,4]
Expression of Zat7 was previously reported to be enhanced in Arabidopsis plants subjected to heat stress [23], as well as in knock-out Apx1 plants grown under controlled growth conditions [16, 17], suggesting that Zat7 expression could be associated with heat or hydrogen peroxide stress
Tolerance of Transgenic Plants That Constitutively Express Zat7, Zat7⌬, or Zat7m to Cold and Osmotic Stress—The EARdomain is found in several different C2H2 zinc finger proteins that are thought to be involved in regulating the response of plants to abiotic stress conditions [1]
Summary
C2H2, Cys2/His2-type zinc finger; EAR, ERF-associated amphiphilic repression; Ler, A. thaliana cv Landsberg erecta; KO, knock-out; WT, wild type; APX1, ascorbate peroxidase 1; aa, amino acid; miRNA, micro-RNA. 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] 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 a result of transcriptional repression by the EAR-motif. A deletion or a mutation of the EAR-motif of Zat abolishes salinity tolerance without affecting growth suppression These results demonstrate that the EAR-motif of Zat is directly involved in enhancing the tolerance of transgenic plants to salinity stress. Our findings demonstrate that the EAR domain of Zat plays a key role in the defense response of Arabidopsis to abiotic stress
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