Analysis of Thermophilic Meiothermus taiwanesis MtDnaJ and MtDnaK in Arabidopsis in Response to Abiotic Stresses
Date Issued
2012
Date
2012
Author(s)
Yang, Tzu-Yi
Abstract
Climate change results in severely abiotic stresses and affects crop growth, development and yields. For the improvement of crop stress tolerance, the stress-tolerant gene mining and applications for transgenic biotechnology application become more important. The extreme environment organism, such as thermotolerance or halophytic hot spring bacteria has been used for its molecular chaperone system related genes to enhance crop stress resistance. The Hsp70 molecular chaperone system is composed of DnaJ (Hsp40)-DnaK (Hsp70)-GrpE (NEF), and the main function is to prevent denatured protein aggregation and precipitation, help the unfold polypeptides refolding and gain the functional composition, and furthermore maintain the protein homeostasis in cells. Previous studies showed that prokaryotes or eukaryotes overexpressing chaperone-related genes could enhance their abiotic stresses tolerance. Thus, in this study we overexpression of Meiothermus taiwanesis MtDnaJ and MtDnaK driven by CaMV 35S promoter or T7 promoter, respectively in Arabidopsis thaliana or Erscherichia coli to test if this strategy could confer the abiotic stresses tolerance in Arabidopsis and E. coli. First, the phylogenic analysis and polypeptides alignment of MtDnaJ/MtDnaK and other organisms showed that indeed these proteins are highly conserved in proteins of various species and may share similar physiological functions. Second, phynotypic analyses of transgenic Arabidopsis under multiple stresses showed that almost all transgenic lines have acquired thermotolerance. On the other hand, under the salt stress, the double cross transformants with MtDnaJ/MtDnaK expressed better phenotype no matter in seed viability, root length, or adult survival rate, especially the MtDnaJ- and MtDnaK- overexpression transformant, H8. This may be due to the establishment of a more complete Hsp70 chaperone system that leads to better gene expression and to confer stress tolerance. In E. coli system, the better growth curve was observed with the overexpression of MtDnaJ and MtDnak fusion gene under normal condition. Combined all the results, the overexpression of prokaryotic Meiothermus taiwanesis MtDnaJ or MtDnaK, especially co-expression of both genes by PCR-fusion, could confer plants with the tolerance of high temperature, salt stress and osmotic stresses.
Subjects
abiotic stress tolerance, molecular chaperone, heat shock protein, hot-spring bacteria, DnaJ, DnaK
SDGs
Type
thesis
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