The Functional Analysis Of Trehalose Phosphorylase TRP In Arabidopsis Under Salt Stress

Salt is one of the most important environmental factors that inhibits plant growth and development, and decreases crop productivity. Plants have developed a lot of mechanisms to cope with salt stress in the course of evolution, These mechanisms include increasing antioxidant enzymes activities to remove excess reactive oxygen species; selective absorption of salt ions; compartmentation of toxic ions and synthesis of compatible osmolytes. Osmotic stress is one of the most important factors that damage plants imposed by salt stress. In order to avoid osmotic stress, plant cells develop osmotic adaptation strategy to low water potentials, maintain the intracellular water content and keep the celluar physiological activities normally. Substances involved in osmoregulation are called osmolyte compounds including inorganic ions such as: Na~+ and K~+ and organic molecules such as: polyols, sugars, amino acids and so on. Trehalose is an important osmolyte of the sugars. The most important biological functions of trehalose are improving the stress resistance of plants. When plants grow under environmental stress conditions such as drought, salt and high temperature, the trehalose as a compatible media plays protective effects on the proteins, membrane and other biological macromolecules or cell structure. However, if trehalose functions in response to salt stress in Arabidopsis is not clear and the molecular evidence is limited.In this paper, functions of the trehalose phosphorylase gene AtTRP in Arabidopsis under salt stress were investigated. Firstly, we isolated and identified a T-DNA insertion mutant line trp by using the PCR-based method. RT-PCR results showed that trp is a knock out mutant. Then we used the mutant to analysis the function of TRP. The seed germination and the seedling growth of mutant trp plants was markedly inhibited under NaCl stress, indicating that the TRP gene plays a role in response to salt stress in Arabidopsis. We constructed the pTRP::GUS vector, transferred it into wild type Arabidopsis plants and obtained some hygromycin-resistance seedlings. GUS staining of the transgenic plants showed that TRP mainly expressed in root, stem, leaf and flower. Meanwhile, we constructed TRP::p-Super1300+ vector, and obtained transgenic Arabidopsis plants overexpressing TRP. The results of transient protoplast transformation by TRP tagged with GFP showed TRP protein was localized in cytoplasm. Taken together, the above results suggest that TRP is involved in salt stress response in Arabidopsis.