Study On Function Of ThMT3Gene From Tamarix Ramosissima In Arabidopsis Thaliana

With industrialization, heavy metal pollution becomes increasingly serious, which leads to significant deleterious not only for the environment but also for human health. Evolutionarily, plants have developed a number of regulatory mechanisms, including heavy metal absorption, transportation, chelation and regional isolation, and detoxification to adapt to the increasing concentrations of metal ions. Metallothioneins (MTs), are low molecular weight, cysteine-rich, heat-stable, metal-binding proteins that are common in plants. The cysteine residues (Cys), which conserved across MTs sequences of different species probably play an important role in metal chelation. Recently, increasing numbers of reports have indicated that plant MTs may play important roles as they exist in animals and fungi. Many studies suggested that MTs might be involved in biological processes as diverse as apoptosis, growth, embryonic development, microspore development, senescence, fruit development, maturation and stress responses. Plant MTs function in metal metabolism and detoxification due to their metal-binding activity and inducibility by heavy-metal ions. In rice, several type1and type2MTs genes have been identified from the rice MTs family. Their exhibited induction patterns vary by the metals to which they are exposed, sucrose starvation, salt stress and other stimuli MTs genes involved in heavy metal metabolism, seed development, and antioxidation. Understanding the biological roles of plant MTs is important enhance forest tree productivity.ThMT3gene(EH057039)was obtained from Tamarix chinensis cDNA library, which was created by Gao and anybody else. It was cloned into the plant express vector ProkⅡ which driven by35SCAMV promotor. The recombinant plasmid was transformed into Arabidopsis thaliana by the floral dip method. To prove the function of ThMT3gene,25kanamycin resistant plant lines were obtained in T2generation after examination. By PCR analysis,23lines was positive. RT-PCR was also performed by randomly selected8transgenic PCR-positive lines, and the result are all positive. In the heavy metal and salt stress test, we used1line which was positive in RT-PCR test. We determined and analyzed the activity of superoxide dismutase (SOD), chlorophyll, malondialdehyde (MDA) contents between the transgenic and control A. thaliana after stress treatment, dry growth, fresh growth and the length of root index variation were also compared. The experience results suggested that the experssion of external gene ThMT3in transgenetic A. thaliana enhanced the resistance to heavy metal, salt and also reduced the damage caused by them. It is effective proved that the Metallothioneins gene can enhance the ability of A. thaliana resistance to heavy metal and salt stress.