Studies On Cloning And Expression Characterization Of NtPx In Tobacco

Oxidative stress was brought due to the stimulation of environmental stress, which had made a great impact on characteristic of physiological and biochemical and metabolic pathway in plant. Peroxidase plays an important role in plant stress response, defense response and the process of growth and development. It takes tobacco as material and cloning a new gene named Ntpx which can code peroxidase. There are fews main results as follows.(1) Ntpx gene was cloned from tobacco, it has a typical peroxidase-4 domain and belonging to plant peroxidase. Ntpx gene open reading frame is 990 bp and can encode a protein of 329 amino acid residues.(2) The expression level of Ntpx from the high to the low followed by flowers, stems, leaves and roots in different organs of mature tobacco plant.(3) The expression of Ntpx gene was the most significant induced by low temperature and ABA and MeJA, more remarkable induced by high temperature and SA and GA, but litter remarkable induced by ET and NaCl. There are performed at first failed and then droped then increased and then decreased in the induced of abiotic stress, including high temperature and low temperature and high salt, and plant hormone, including SA^ GA^ ABA?ET?MeJA. However, it was increased firstly and then decreased during in the induced of drought stress.(4) Location of Ntpx protein was detected by the subcellular localization in onion epidermal cells after pBI121-Ntpx-GFP fusion expression vector was constructed. The result shows that Ntpx protein is mainly located in nucleus.(5) Expressed of Ntpx after pET30a(+)-Ntpx-GFP fusion expression vector was constructed. The results showed that the expressed Ntpx protein had the enzyme activity. Moreover, Ntpx protein has the higher enzyme specific activity when the bacteria oscillated in 200 rpm/min,then induced 10 h under the condition of 0.05 mmol/L IPTG, The enzyme specific activity was up to 8.617 U.g-1.min-1.The conclusions of the above studies was owed an important effect to future analyse biological function and molecular mechanism of Ntpx in tobacco.