The Study Of The Transgenic Arabidopsis With Overexpression Of Endoplasmic Reticulum Small Heat-shock Protein

Most eukaryotic cells response to high temperature with the production of heat shock proteins. Plants can synthesize a large number of small heat shock proteins whose molecular weight are between 15-42kDa under the condition of heat. The expression of some smHSPs will be 1% of the total protein in plants. Under non-stress conditions, little smHSPs could be detected in the nutrition organizations of higher plants. However, the expression of smHSPs increase more than 200 times under the heat shock stress condition and become the major protein components. Endoplasmic reticulum smHSPs located in the endoplasmic reticulum and existing literature showed that the overexpression of tomato LeHSP21.5 could alleviate ER-stress and reduce unfolded protein response induced by low temperature and salt stress. Helm cloned the small heat shock protein AtHSP22.0 cDNA from Arabidopsis thaliana endoplasmic reticulum. The AtHSP22.0 cDNA has a putative signal peptide and a carboxyl-termina1 tetrapeptide SKEL, which is similar to known ER retention signals. In vitro, AtHSP22.0 mRNA translation product localized in the endoplasmic reticulum. In this study, a DNA construction pCAMBIA3301, including the endomembrane small heat shock protein cDNA under the control of cauliflower mosaic virus 35S promoter, was introduced into the genome of Arabidopsis using Agrobacterium.In order to study whether the Arabidopsis thaliana plants overexpress AtHSP22.0 protein also have resistance to abiotic stress we studied the overexpression mutants. We mainly discussed the role of AtHSP22.0 protein in Aradopsis thaliana during the tunicamycin stress and studied the differences from transgenic Arabidopsis thaliana and wild-type phenotypes under salt, drought, high temperature stress, to understand on the mechanism of stress tolerance and enhance the capacity of stress tolerance for plants. The results showed that the AtHSP22.0 protein played an important role in the abiotic resistance of Arabidopsis thaliana:1. The generation of Aradopsis thaliana with overexpressed AtHSP22.0 The constructed pCAMBIA3301 vector was introduced into Arabidopsis thaliana by Agrobacterium tumefactions-mediated, and the constitutive expression of AtHSP22.0 transgenic Arabidopsis thaliana lines was generated. Northern analysis confirmed the constitutive expression of the AtHSP22.0 transcript: the normal expression of the AtHSP22.0 transcript could be examined in the transgenic Arabidopsis thaliana lines at 25℃.2. Overexpression of AtHSP22.0 improved tunicamycin tolerance of Arabidopsis thaliana lines.In this study, transgenic and wild-type Arabidopsis plants were both treated with tunicamycin and the results showed that the overexpression of AtHSP22.0 enhances the capacity of tunicamycin tolerance; the seed germination rate of transgenic Arabidopsis thaliana was significantly higher than wild type Arabidopsis thaliana seeds.3. Overexpression of AtHSP22.0 improved high temperature tolerance of Arabidopsis thaliana lines.When transgenic and wild type Arabidopsis thaliana were under high temperature stress, the tolerance of transgenic was better than the wild type.4. Overexpression of AtHSP22.0 alleviates UPR caused by tunicamycin.Under concentration gradient of tunicamycin, the expression of BiP mRNA was significantly different between transgenic and control Arabidopsis plants. In control Arabidopsis thaliana, BiP mRNA expression increased with tunicamycin concentrations increased rapidly, which is the performance of plants under stress injury. While in transgenic Arabidopsis thaliana, BiP mRNA expression was significantly lower than the control, indicating that overexpression of At HSP22.0 alleviates UPR caused by tunicamycin.