engleski

Genotypic characterisation of indigenous Sinorhizobium meliloti strains isolated from Istrian soils

Symbiotic relation between nodule bacteria, Sinorhizobium meliloti and alfalfa (Medicago sativa L.) enables significant entries of biologically fixed nitrogen in soil. The inoculation of alfalfa seeds with efficient S. meliloti strains is recommended in order to increase the utilization of symbiotic nitrogen fixation. The presence of indigenous S. meliloti strains in soil can limit the inoculation response even with highly efficient commercial strains. The aim of this investigation was to isolate and identify indigenous S. meliloti strains from different soil types of Istria and to determine genetic diversity within rhizobial field population. Physical and chemical properties of soil samples were determined in order to describe the field sites of rhizobial isolation.The seventeen S. meliloti isolates were characterised by using RAPD-PCR and ERIC-PCR methods. Results of each method were converted to two-dimensional binary matrix and analysed using a biostatistical program NTSYS-pc. The results revealed the presence of indigenous S. meliloti strains. Among indigenous strains a considerable level of genetic diversity was determined. The highest differences were determined between strain Is4/2 and all other isolates. The highest level of similarity was determined between strains Is10/2 and Is2/2 that were isolated from different soil types. The results indicated that genetic diversity level of natural field population was not influenced by different soil properties.

Sinorhizobium meliloti; alfalfa; Medicago sativa L.; nitrogen fixation; indigenous; RAPD-PCR; ERIC

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