The Function Of O₁ Type Thioredoxin Gene In Arabidopsis Thaliana Under Environmental Stress

At present, within the scope of world, the phenomenon of alkali-salt soil aggravate gradually, becoming one of the serious environment problems.Under salt coerce, plant grows slowly, the metabolism is repressed, appears a salt spot, sliced leaf, even dying. In recent years, along with the rise of the biology engineering, make use of the biology measure to improve salt soil, become the main improvement measure to hold out for long time, stability and be advantageous to the conservation of water and soil and ecosystem balance. So it makes sense for us to study the response mechanism of oxidative stress, finding stress related genes and breeding for stress tolerance in crops.Thioredoxin (Trx) is a kind of low molecular weight (12kD), heat stability, acidity protein with a highly conserved and prominent active site sequence WCG/PPC. They take part in many reaction to play their Oxidize and revivification function via catalyse thiol-disulphide oxido-reduction. Trxs are important enzyme vitality regulate proteins. Their functions are key to cells, such as:alleviate oxidize coerce to cells, control growth, cell procedure death, vitality of cell factor and chemotaxis factor.For decades, people had more and more information about it, characteristics, function...etc., established necessary foundation.for better utilization it.In this study, the Arabidopsis thaliana Trx gene AtTrx o1 was cloned from the green leaves by RT-PCR.And we did a particular research for the AtTrx o1 type gene.To understand the genes function in vitro, we were cloned the Trx o1 genes into the prokaryotic vector pQE-30. pQE-30-AtTrx o1 plasmid was transformed into E. Coli M15.After the inducement with IPTG, the His-AtTrx o1 fusion protein were purified by Ni+-sepharose affinity column and analyzed by SDS-PAGE.But the purification of the target protein can not use to do further research.We tried to solve this problem,but failed.In the future research,we will continue try our best to finger out this issue,so that we can know the physiology and biochemistry characteristic of the target protein better.To understand the responsive relationship between Trx o1 and environmental stress, the transcription expression profile of Trxs was studied by Northern blot analysis using A. thaliana suspension cells under several stresses. The results showed that the accumulation of Trx o1 mRNA was observed in salts (NaCl, NaHCO3), ABA, and H2O2 conditions and the intensity of stresses influenced the expression of Trxs. These results suggested that the expression of Trx o1 responses to several abiotic stresses, but the response mechanisms are different.To further investigate the role of the Trx o1 tolerance, AtTrx o1 was cloned into pBI121, and introduced into A.thaliana by Agrobacterium tumefaciens-mediated transformation using the vacuum infiltration method. The independent and stable expression lines of over-expressing Trx o1 was confirmed by PCR analysis.Salt tolerance of the independent transgenic lines in germination was examined, and the wide type plants were restrained more heavily than the the transgenic plants under NaCl stress. For treatment with 50 mM NaCl, the root length of AtTrx o1 increased about 32.5%;for treatment with 100 mM NaCl, the root length of AtTrx o1 increased about 62.5%; for treatment with 100 mM NaCl, the root length of AtTrx o1 increased about 53%; and under 200mM NaCl, the wide type could't germinate completely, but the trasnsgenic plants harboring CaMV35S: AtTrx o1 could germinate though the growth was hampered. In oreder to confirm the relationship between AtTrx. o1 gene with the salt stress in the development of the plants, the transplant experminents were done under salt stress.The results indicated that the salt tolerance of the transgenic plants increased the transgenic plants grown better than the control. Under 100 mM NaCl stress, the growth of the wide type plants were restrained and the leaves showed some chlorosis and decreased vigor, but the transgenic plants harboring AtTrx. o1 have a higher resistance.The research suggested that O1-type A.thaliana thioredoxin gene plays an important role in abiotic stress tolerance and can enhance the transgenic plants'ability to salt stress.