Expression Vector Construction And Function Determination Of EIF1A Gene From Tamarix.s

This study was aimed to obtain the eIF1A gene from Tamarix.sp, that is a drought resistance and salt tolerance plant, and to clone it into the plant expression vector pROK II. Eighty-nine kanamycin-resistant shoots were obtained from transgenic tobacco via Agrobacterium-mediated transformation systems and 7 excellent lines were subjected to PCR examination and PCR-Southem blotting analysis, indicating that all the transgenic plant;were positive. Furthermore, the results of reverse transcription-PCR and real-time quantitative RT-PCR approved that eIF1A gene had been integrated into tobacco genome and can be expressed. However, the expression rates varied from 14.61 to 290.42 times against the housekeeping gene GAPDH (glyceraldehydes-3-phosphate-dehydrogenase).(1) The T₀ generation of transgenic tobacco was subjected to salt and drought stress treatment, and their tolerance and resistance were analyzed. The results revealed that the most of the transgenic seedlings could grow well in the medium containing 240 mmol/L NaCl, with a radication ratio bigger than 50% and a salt-injury index less than 57.5% whereas the control line could not take root with a high salt-injury index of 67.7%, which in turn demonstrated that the salt tolerance of transgenic lines improved. Under different concentration of NaCl, the weight increments of all the transgenic lines were higher than that of the control line. With concentration of NaCl increases, the growth rate of control line decrease remarkably, but the weight of the transgenic lines increased evidently than that of the control line. We also analyzed the effects of different NaCl concentrations on tobacco cell membrane systems. The results showed that relative conductivity and MDA content of transgenic plants were both lower than that of the control line, suggesting that injure degree of the cell membrane system of transgenic lines were minor. The determination of SOD showed that both of transgenic and non-transgenic tobaccos both raised with the salt concentration increase, but amplitude of transgenic plants was higher.Studying on potted plants of T₀ under drought conditions, we concluded that during 20d drought stress, drought-injure index of control line was up to 52.27% while it was only 30.56% 46.67% in transgenic lines. Moreover, relative conductivity under 10d and 20d drought stress had a trend of raise in both transgenic and control plants, but it increased slightly in transgenic tobaccos, the SOD content and soluble protein of the transgenic lines and the control line increased with the duration of the drought stress.(2) T₁ generation of transgenic tobaccos was subjected to salt stress treatment at a concentration of 340mmol/L NaCl, and the relative conductivity and MDA content were analyzed. The results showed that cell membrane systems of transgenic lines were slightly injured. The average SOD content of tobacco with eIF1A gene was 1.17 times than control line, and the salt-injured index waslower than non-transgenic line.