Functional Analysis Of MdSPDS1 And Primary Study On Transgenic Populus Tomentosa Carr.

The problem of the salty soil has represented some of the most significant constraints to agricultural and forestry productivity. It has become an important topic and hotspot on the researching of the future development in agriculture and forestry that how to make use of the large quantity of salty soil and salty water resources. Polyamines play an important role in plants to enhance environmental stress tolerance. So, functional analysis of MdSPDS1 gene which is encoding Polyamines biosynthesis has been carrying out. And transgenic Populus tomentosa Carr. with MdSPDS1 was abtained. The major results and conclusions are described as follows.(1) MdSPDS1 was transferred to Nicotiana tabacum by Agrobacterium–mediated, and the expression of MdSPDS1 gene was analyzed by Real time Quantitative PCR. The contents of three main polyamines -- Put,Spd,Spm were detected by HPLC. The result showed that the Spd levels in transgenic plants were 2-3 fold when compared to untransgenic plants.(2) It was found that transgenic plant D14 which has high expression of MdSPDS1 could live under 400mM NaCl stress. Under this stress, contents of polyamines were detected to learn the changes of three main polyamines. The results illustrated that the increase of Spd content and (Spd+Spm)/Put played an important role in enhancing tolerance to salt stress. On the other hand, it was found that the ability of resistance to TMV in D14 was higher than WT, and PAs levels altered by TMV infected. Put levels in WT were enhanced more than 5-folds when compared to healthy control; while Spd levels in D14 were enhanced 4-folds. The result showed that increase of Spd was one of the reseaons of enhancing plant resistance to TMV.(3) The primary transformation system was established in Populus tomentosa. The integration of the MdSPDS1 gene into plant genomes of transgenic Populus tomentosa was confirmed by PCR and Southern blot analysis. The expressions of MdSPDS1 gene and polyamines levels were also detected. The result showed that the Spd levels in transgenic plants were 1.65-folds when compared to untransgenic plants. It was also found that transgenic Populus tomentosa could live under 200mM NaCl stress.