Functional analysis of the Hikeshi-like protein and its interaction with HSP70 in Arabidopsis

Heat shock proteins (HSPs) refold damaged proteins and are an essential component of the heat shock response. Previously, the 70 kDa heat shock protein (HSP70) has been reported to translocate into the nucleus in a heat-dependent manner in many organisms. In humans, the heat-induced translocation of HSP70 requires the nuclear carrier protein Hikeshi. In the Arabidopsis genome, only one gene encodes a protein with high homology to Hikeshi, and we named this homolog Hikeshi-like (HKL) protein. In this study, we show that two Arabidopsis HSP70 isoforms accumulate in the nucleus in response to heat shock and that HKL interacts with these HSP70s. Our histochemical analysis revealed that HKL is predominantly expressed in meristematic tissues, suggesting the potential importance of HKL during cell division in Arabidopsis. In addition, we show that HKL regulates HSP70 localization, and HKL overexpression conferred thermotolerance to transgenic Arabidopsis plants. Our results suggest that HKL plays a positive role in the thermotolerance of Arabidopsis plants and cooperatively interacts with HSP70.     

Analysis of Arabidopsis thaliana transgenic plants transformed with CER2 and CER3 genes in sense and antisense orientations

 A number of genes involved in the biosynthesis of the epicuticular wax (EW) of Arabidopsis thaliana have recently been isolated through genetic approaches. In view of the evidence in favor of the importance of EW compounds in the adaptation of higher plants to a number of physiological and ecological stresses, we have used clones of some of these genes to genetically engineer constructs with which to manipulate EW biosynthesis in transgenic A. thaliana plants. All our constructs were placed under the control of the near constitutive CaMV 35S promoter. We were able to complement mutant plants with the construction in the sense orientation as well as induce phenocopies of the eceriferum phenotype by transforming wild-type plants with both the sense and antisense constructs. We observed reduced fertility in the wild-type plants transformed with the 35SCER3sense or 35SCER3antisense constructs but not in those transformed with the 35SCER2sense or 35SCER2antisense constructs. Received: 28 December 1997 / Accepted: 31 March 1998     

禾本科植物单锌指家族基因对逆境应答的研究进展

转录调控是植物生长发育、逆境反应、信号转导、抗病性等一系列基因表达的最主要调控形式,转录因子是参与基因转录水平调控过程的重要反式因子。单锌指(DNA binding with one finger,DOF)转录因子是植物特有的一类转录因子,包含一个C_2-C_2锌指结构,其N-末端保守的DOF结构域是能与DNA和蛋白相互作用的双重功能域,在植物生长发育过程中参与多种生物学过程。尽管已有研究报道DOF家族基因参与植物抗逆响应,但其在禾谷类重要粮食作物中的作用机制还极不明确。本文通过对禾本科植物DOF家族基因系统进化分析及组织表达和诱导表达分析,综述了DOF家族基因参与植物胁迫应答方面的相关研究进展,为进一步深入了解禾本科植物抗逆机制提供重要参考。