Construction And Function Identification Of Plant Expression Vector Of The Late Embryogenesis Abundant Protein Gene

The LEA gene was obtained from Tamarix.sp, which is a drought resistance and salt tolerance plant. It was cloned irto the plant express vector pROK Ⅱ. The recombinant plasmid was transformed into tobacco by Agrobacterium mediated genetic transformation. The purpose is to identificate the function of LEA gene. 84 kanamycin-resistant buds was obtained in study the transform efficiency was 34 percent. Through differentiation, we selected 24 excellent lines to PCR test. All the lines were positive in PCR. In Southern blotting hybridization, we checked 10 transgenic plants selected from 24 plants randomly. The results demonstrated that foreign target gene had been integrated into tobacco genome already. The results of reverse transcription-PCR and real-time quantitative RT-PCR approved that the transformed gene can be expressed. However, there were different among the 10 lines about expression level of LEA gene. The expression level of LEA gene were 15.52 — 115.49 times than that of GAPDH gene in the 10 lines.In this study. we determined the peroxidase ( POD ) activity , malondialdehyde(MDA) contents and the relative conductivity of the 10 transgenic tobacco, compared the relative growth and drought-irjury index variation under drought condition. All the results confirmed that the LEA gene, which obtained from Tamarix.sp can enhance the drought tolenance of transgenic plants. In this research we found that the POD activity of transgenic plants and control plants were all increased after drought stress, however, the POD activity of transgenic plants was significantlv higher than that of control plants. In the 10 transgenic tobaccos, TL15 and TL10 have the highest POD activity, which exceeded the control plants 68.1% and 61.0% respective!}. Even the TL19, which have the lowest POD activity in the 10 transgenic plants was higher than the control plants 18.0%. Same to the POD activity, the MDA content of the 10 transgenic plants were also increased after drought stress, but the MDA content of the transgenic plants was significant lower than that of control plants. The results of multiple comparisons indicatec. that the MDA content of TL8, TL15 and TL 16 achieved the significant difference level to that of the control plants. The MDA content of the three transgenic lines above was lower than that of the control planrts 46.2%, 46.3% and 43.3% respectively. The relative conductivity mensurate results were same to the MDA content experiment results. The results of multiple comparisons indicated that the relative conductivity of all the transgenic plants achieved the significant difference level to that of the control plants except TL22. In the 10 transgenic tobaccos, TI.8, TL15 and TL16 were the excellent lines that the relative conductivity lower than the control plants 38.3%, 36.6% and 37.3% respeetivelyThe relative growth of the trarsgenic plants was at the range from 205.0% to 341.1%. higher than that of the control plants—-170.3%. TL8, TL15 and TL16 had the highest relative growth, which higher than the control plants 91.3%, 98.8% and 100.3% respectively. This result consistent to the MDA content and relative conductivitv outcome. Under the same droughtstress condition, the drought-injury index of all the transgenic lines was lower than that of the control plants. To the control plants, the drought-injury index was 56.9%. and to the transgenic plants the lowest one was TLlf, the index was 28.1%. Howere, the highest one was TL10. achi\ed43.8%.All the experiments results above indicated that the LEA gene have the function of protect plant organize and cell under drought stress condition, that was the LEA gene from Tamurix.sp could enhance the stress tolerance of plants.