摘要(英) |
Plants respond to evaluated temperature by inducing the heat shock response. The heat shock response (HSR) protects plants from cellular damage not only by accumulation of heat shock protein, but also by accelerated cooling down of biological system mediated by stomatal opening. The plant hormone abscisic acid (ABA) normally accumulates in response to drought, cold and salt stresses. Previous study indicated that rice OsRZFP34 was identified as a heat- and ABA- responsive gene according to analyses of microarray expression profile and reverse transcriptase polymerase chain reaction (RT-PCR). The complex cascades of gene expression in various stresses can contribute to stress response, which further enhances the stress tolerance. To identify the crosslink between high temperature and ABA-related response in Arabidopsis, we characterized the Arabidopsis At5g22920, also named AtRZFP33, which is a homolog of rice OsRZFP34. AtRZFP33 belongs to zinc finger subfamily, containing a deduced RING zinc finger signature. Using quantitative RT-PCR to analyze tissue specificity and expression pattern of AtRZFP33, we found that AtRZFP33 was significantly reduced by heat and ABA treatments. Although zinc finger protein is usually characterized as a transcription factor, subcellular localization of AtRZFP33-GFP in onion epidermal cells showed that AtRZFP33 was localized not only in nucleus but in the cytosol. To study the role of AtRZFP33 in resistance to stresses, we examined the loss of function of AtRZFP33 in a T-DNA insertion mutant, SALK_017562. Thermotolerance was decreased in atrzfp33 mutant line in seed stage; in seedling, we found atrzfp33 mutant line was resistant to drought and chilling stresses, resulting from its stomatal closure. The stomatal aperture was smaller in atrzfp33 mutant line, but 20% higher in transgenic plants overexpressing AtRZFP33 relative to wild type. It reflects that AtRZFP33 may play a negative role in stomatal closure controlling mechanism. Using quantitative RT-PCR to analyze the expression of ion channels related to stomata opening, we found that KAT1, OST2 and MRP5,were upregulated in atrzfp33 mutant, and downregulated in overexpression plants. Moreover, we transformed 35S::AtRZFP33 construct into nced3, abi1 and abi2 mutant lines. Stomatal aperture of nced3/AtRZFP33OX and abi2/AtRZFP33OX were higher than single mutants, but there was no difference between abi1/AtRZFP33OX and its single mutant. Collectively, these results indicated that AtRZFP33 may functions in heat and ABA stress response by regulating the stomatal mechanism.
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