Showing 2 results for Sinorhizobium Meliloti
M. Sepehri, N. Saleh Rastin, H. Asadi Rahmani, H. Alikhani,
Volume 10, Issue 1 (4-2006)
Abstract
Heavy metals have deleterious the effects on nodulation and N2 fixation of Rhizobium- Legume symbiosis, due to their inhibitory effects on the growth and activity of both symbionts. This research has been undertaken to evaluate the effect of Cd tolerance of native rhizobial strains on diminution of the Cd detrimental effects on Sinorhizobium meliloti-alfalfa symbiosis. For this purpose, a greenhouse experiment was conducted based on Randomized Complete Block Design. The treatments in this experiment included: plants inoculation with 6 bacterial strains (sensitive, partially tolerant and tolerant to Cd), 5 levels of Cadmium (0, 2, 5, 10, 20 mg/kg soil) and non-inoculated control. In different levels of Cd, the effects of bacterial inoculation on root nodule number and total amount of nitrogen in plant shoot were compared. The results indicated that soil pollution by Cd even at 2 mg/kg had significant effect on symbiotic properties of rhizobial strains, and according to Cd tolerance of various strains, the mentioned effect was different. Decreasing effect of Cd concentration on root nodules and nitrogen concentration in plants that were inoculated with sensitive strains in comparison with plants inoculated with tolerant strains was 68.31% and 40.8%, respectively. In this research, R95m was introduced as the best strain because of its ability for nodulation and nitrogen fixation.
M Talebi, M Bahar, Gh Saeedi, A Mohamadi,
Volume 13, Issue 47 (4-2009)
Abstract
To characterize the geographical distribution of medicago-nodulating rhizobia in western regions of Iran, 950 Sinorhizobium isolates were trapped from a combination of two local alfalfa populations (Hamedani, Nikshahri) together with a foreign cultivar ( Kodi) and soil samples from eight sites across Kurdestan, Kermanshah, Eastern Azarbayjan and Lorestan provinces. Also, a total of 45 isolates were obtained from nodules of naturally grown Melilotus officinalis (14 isolates) and Trigonella foenum-graecum (31 isolates) plants in Isfahan. On the basis of PCR partial amplification of the plasmid born nod box gene and chromosomal mucR gene of the isolates,16S ribosomal DNA PCR-restriction fragment length polymorphism analysis, and the nucleotide sequence, three isolates from alfalfa, seven isolates from M. officinalis and 13 isolates from T. foenum-graecum were proved to be Sinorhizobium medicae. The remaining isolates (943 from alfalfa, seven from M. officinalis and 18 from T. foenum-graecum) were identified as S. melilloti. Both species, S. meliloti and S. medicae, were recovered from nodules of all the hosts although S. meloti was clearly more dominant in nodulating different populations of alfalfa. Taken together, these results indicated that the abundance of S. meliloti is independent of the site of isolation and have a wide geographical distribution. In this study, the banding pattern resulting from PCR amplification of 16S rRNA gene, followed by digestion with Rsa I, clearly differentiated S. meliloti and S. medica strains, showing that PCR-RFLP is an appropriate method to discriminate medicago-nodulating rhizobian with relative rapidity.
