| As the colse relative of Arabidopsis Thaliana, Thellungiella salsuginea is well adapted to salty environment, who can resist the assault of 500mM NaCl. The mechanism of plants salt tolerance can be divided into four catergories: the first kind refers to those equipped with salt glands like Limonium Sinense, who secretes the excessive salt ions out of cells to maintain the homeostasis of cells. The second are those who can regionalize salt ions into vacuole to avoid high concentration ions in cell plasma, for example, Suaeda salsa(L.)Pall can do this by pumping large amount of salt ions into the vacuole and cause leaf carnification. The third are those who equipped with strong ability to resist the assault of ROS, the level of ROS may rise to a high level when plants are treated with salt, and the activity of salt may cause damage to the macromolecular, like proteins, nucleic acids. Plant can relieve the damage by accumulating high concentration of redundancy materials like APX etc to neutralize the ROS, or plant can diminish the damage through enzyme activity, thus release the damage to cells caused by ROS. The mainstream enzymes are those like CAT, POD, SOD, MDAR, etc. The fourth are those possess strong ability of osmotic adjustment, plants do this by increasing the number of solute particles present in plant cells. Compatible solutes are a small group of chemically diverse organic compounds that are highly soluble and do not interfere with cellular metabolism, even at high concentration, materials like this are the amino acid proline, the quaternary ammonium compoundβ-alanine betaine, etc.While Thellungiella salsuginea, which lacks the salty glands and pumps to restrict ions, can resist the shock of salt by no way but diminishing the damage caused by ROS and maintaining water by accumulate osmotic protective material. Here we would like to do research on the ability of Thellungiella salsuginea to resist ROS to correlate the relationship with its ability to tolerate salt environment.The guideline of this research is as following: firstly, we try to find out the most active ROS eliminate enzymes and clone their coding genes, then we knock down this gene by RNA interfere, and measure how the ability of plant to resist stress change. So the first step of our research is to find out the target gene, we do this by firstly to search the gene bank to find out the EST of Thellungiella salsuginea and do BLAST on NCBI to screen those are likely to be ROS eliminate enzymes. Then we design primers, using RNA purified from wild type plants grown in normal conditions and salty conditions as temples to amplify targeted genes and qualify the copies of the genes with the hope of finding out the one whose transcription changed the most after treated with salt. However to our disappointment the genes we choose as pools do the same change after treated with salt. So we choose the most of them as the following targets, they are DHAR and Fe-SOD. We choose 300 base pair as the targeted sequence to clone and design silencing vector. After transformed into the Agrobacterium, we transform the Thellungiella salsuginea using the flower dipping method. After screened with herbicide and PCR identify to make sure gene transduction successfully. Then we testify the silencing rate using NORTHERN protocol. Then we measure the ability of salt tolerance of plant to correlate the two aspects. However because of the complexities of plant salt tolerance mechanism: through enzyme way or nonenzyme way, different functional molecular, so the lose function of one gene can hardly cause any change in the ability of eliminate ROS, which can be seen from our experiment, which reflects there are redundancy mechanism in the plant.
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