جداسازی Rhizobium از ریزوسفر خارشتر (Alhagi persarum L.) در ایران

Camel thorn (Alhagi persarum L., Fabaceae) is an important perennial weed that can be found in nearly all regions of Iran. It is used as herbal medicine and more recently cultivated as animal fodder. Rhizobia are essential for sustainable agriculture due to their ability to fix atmospheric nitrogen and enhance plant growth. Their complex genetic makeup and metabolic interactions with host plants enable them to adapt to various environmental conditions and form effective symbiotic relationships. This symbiosis not only benefits leguminous plants but also has broader ecological implications, including potential applications in biofertilization and plant protection. In order to find novel rhizobia with specific characteristics, rhizosphere soil was collected from a depth of 15 cm in Alhagi persarum plants in pistachio orchards located in Rafsanjan county (Kerman province, southeast Iran) during the summer of 2022. The samples were placed in a sterile plastic bag to be brought into the laboratory for the isolation and characterization of bacteria. Isolations were carried out on Yeast mannitol agar (YMA) and sucrose nutrient agar (SNA, 1% sucrose) using the serial dilution method. Bacterial colonies resembling Rhizobium (fast growth rate, white and glistening colonies) appeared on YMA plates. Isolates were Gram negative and positive for oxidase and catalase. The 16S rRNA region of a representative isolate were amplified and sequenced (GenBank accession number: OR085848). BLAST analyses showed that the Camel thorn isolate had 100% nucleotide sequence similarity to Rhizobium sp. strain BD1, which was isolated from Albizia lebbeck in India. To the best of our knowledge, this is the first report of the presence of Rhizobium sp. in the rhizosphere of Alhagi persarum in Iran.