مطالعه اثرات بيوشيميايي سيستم تثبيت ازت AGROBACTERIUM TUMEFACIENS در برخي از ارقام يونجه

Study of the effects of nitrogen fixation system on biochemicals of Agrobacterium tumefaciens in some medicago cultivars

Nitrogen is one of the most important elements in plants. But gas is not usable by most higher plants. For many years nitrogen fixation by micro-organisms has been proved. Many researchers pointed that Agrobacterium tumefaciens has ability to fix nitrogen. To investigate the role of this bacterium in nitrogen fixation; three cultivars of Medicago sativa (Bami; Australian and American cultivars) which were either inoculated with nif"nod+ sinorhizobiumorwith sinorhizobium contained plasmid (pSRK9) were used and compared with wild type and control. The results showed that those plants which had higher growth; had the lower amount of reduced sugars in their roots. The lowest amount of sugar was recorded in plants which were inoculated with nifK~(pSRK9). The results indicated that; there is a correlation between decrease in roots sugars and increase in dissolved protein. Measurement of the total protein of the stem and leaves showed that those plants were inoculated with sinorhizobium contained plasmid (pSRK9) had the most amount of protein in comparison to the other plants. Those plants which were inoculated with sinorhizobium containd plasmid nifK"(pSRK9) converted higher amount of acetylen to ethylen and the rate of ethylen producted were higher significantly. In Conclusion, in our study the system which include nif gene effectively increased growth of the three Medicago sativa cultivars.