| As plants are sessile organisms, they are forced to survive in environments with variable environmental stresses such as cold stress and osmotic stress which include drought and high salinity. Cold stress is one of the major environmental stresses that limit crop productivity, quality, and post-harvest life. Many plants, including Arabidopsis, increase in freezing tolerance in response to low non-freezing temperatures, a phenomenon known as cold acclimation.In research of plant stress responsion, the CBF cold-response pathway plays an important role in the cold stress responsive. The CBF regulons (C-repeat/dehydration responsive binding factor), which is the key element, was encoded by DREB/CBF family. CBF gene widely exists in higher plants, and the DREB/CBF regulons DREB/CBF regulons plays a key role in the cold responsion, and almost 90ï¼…of the most highly induced genes in the cold stress. DREB/CBF regulons induced by low temperature quickly, and it bound the cis-element CRT/DRE which exist in the promoter of most stress-response gene to induce the expression of cold responsive genes, which will improve the cold, dehydration and salt resistant of the plant.Recent researches focus on the plants lived in hot or temperate zone, such as extensively characterized model plant Arabidopsis thaliana. Descurainia Sophia, which is from altiplano, can endure cold stress and hold much adaptability. Arabidopsis thaliana and Descurainia Sophia both belong to Cruciferae plants with different cold resistance. It has been proved in our former physiologic research. It is very important for further research about the mechanism of plant cold resistance and breeding economic crops with excellent cold resistance to clone and determine of CBF gene Descurainia Sophia and analysis its function. Based on the EST of a CBF gene in Descurainia Sophia, in this study we got the following results:â… . Cloning of full length cDNA of DsCBF1 and the EST of DsCBF2 in D.Sophia. We cloned the 946bp full length DsCBF1 cDNA by the 5'RACE method of CLONTECH. We aligned DsCBF1 and CBF genes of some species, and designed the degenerate primers according to their structural conservative region. The 640bp EST sequence of DsCBF2 gene has been gained by using homologous clone.â…¡. Bioinformatics analysis. We used bioinformatics tools analyzing the DsCBF genes and the deduced protein of DsCBF1. The whole open reading frame (ORF) of DsCBF1 was 642bp. The DsCBF genes are highly homologous, especially the bases in the N terminal of ORF. Compared with other DREB1/CBF proteins known, DsCBF1 protein has the characteristic domain of DREB1/CBF family. Unrooted phylogenetic tree showed that type of DsCBF1 protein in D.Sophia corresponds to AtCBF3 types in Arabidopsis thaliana.â…¢. Short-term changes in mRNA levels of DsCBF1 and DsCBF2 corresponding to different light conditions. This research was made by Real-Time Quantitative PCR. The results indicated that the DsCBF1 and DsCBF2 can be induced by cold stress quickly, but they have different mRNA levels at the same time and at different times of the highest mRNA levels, that suggests excellent cooperation of cold resistant. DsCBF1 did not express in the room temperature, which is same as the condition of DsCBF2, and CBF mRNA will accumulate quickly until 10 degree, when the temperature is lower, the mRNA will accumulate more. When plants are back to 22 degree again after being kept in 4 degree for 2h, mRNA descends fast. It dedicated the mechanism of the regulation of CBF genes in the cold responsive pathway. This basic works will help us do further research on the function of DsCBF family.â…£. Transgenic Arabidopsis overexpressing DsCBF1 was generated. The ORF of DsCBF1 gene was transformed to wild-type Arabidopsis by the floral dipping with Agrobacterium tumefaciens. Our work will help us go further in research on transgenic Arabidopsis and the function of DsCBF1 in vivo.
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