Enabling Tobacco plants to hyperaccumulate heavy metals
Our challenge is to solve the problem of heavy metal polluted soil, especially in areas of high industrial use, such as mining. Extensive coal mining in the past released a high amount of heavy metals, such as lead or cadmium into the soil, thus making the soil unsuitable for agricultural use. Since plants like salad have the tendency of incorporating these heavy metals, consuming those plants is unhealthy for humans and other animals. Our goal is to enable a tobacco plant to hyperaccumulate cadmium and lead by transferring genes of Arabidopsis halleri(A. halleri) and adding other special abilities that support the accumulation of heavy metals. Tobacco is a plant with deeper roots than A. halleri, so it is reasonable to use tobacco in cleaning up polluted soil. Heavy metals not only occur in the first few inches of soil, due to rain, so it is important to use a plant which can go deeper into the ground than A. halleri. Furthermore, tobacco has a higher biomass, so it can accumulate and store a higher amount of heavy metals.
A. halleri is distributed in and around central/eastern Europe where it occurs on soils contaminated with Zinc (Zn) and Cadmium (Cd) such as the German Ruhr area. In comparison to other species, root tolerance tests show that A. halleri tolerates higher Zn/Cd concentrations. In research work we identify the genes that are responsible for heavy metal hyper accumulating and decided to use HMA3 for the first step of introducing a heavy metal hyperaccumulating gene to tobacco. We got it synthesized by IDT (integrated DNA Technologies).
To insert our target gene in PSB1C3, we used different restrictions enzymes (link zu parts) and followed protocols (link zu experiment). For more information about the theory and designing step pleasevhave a look into design.
You want information about the outlook, what happens after iGEM 2018? Just continue reading:
After creating E. coli, containing the HMA3 gene, we are going to use Agrobacterium Tumefaciens for transferring the gene into a tobacco plant, like shown in the figure below. This is because E. coli is not able to transfer genes into plants but A. Tumefaciens is. If you are wondering what happens to hyperaccumulating tobacco plants: Heavy metals are often used in the IT and computer industry, for example to produce lead acid batteries. Since our tobacco plant contains a high quantity of valuable heavy metals, we plan to recycle those, thus protecting the environment and its rare and most importantly finite resources.
Getting started: this picture was taken on our first day in the lab. First steps of cultivating our A. halleri.