1 research outputs found
Fenotipska i genotipska raznolikost sojeva Sinorhizobium meliloti izoliranih iz tala Zadarske županije
Soil bacteria, Sinorhizobium melilo i is of great agricultural importance because of its ability to fix atmospheric nitrogen in symbiosis with alfalfa, a very valuable forage crop. The main aim of this study was to evaluate tolerance of indigenous S. melilo i strains to stress environmental conditions. Twenty rhizobial strains, isolated from different regions in Croatia, were genotipically characterized to assess diversity amongst natural population. Stress tolerance assays were performed in order to select indigenous rhizobia with tolerance to unfavorable soil conditions. The growth of the strains was studied at different pH values, temperatures, NaCl and heavy metals concentrations. The results of 16S rDNA genotyping using PCR/RFLP analysis showed that 17 isolates could be assigned to S. melilo i while RAPD and ERIC-PCR fingerprints revealed significant genetic diversity among indigenous rhizobial strains. In comparison to the reference strain, higher resistance to adverse growth conditions of indigenous S. melilo i strains was determined. Most of the strains grew at temperatures higher than optimal and tolerated both acidic and alkaline environment. It was found that indigenous strains tolerate extremely high NaCl concentrations. Better understanding of rhizobial response to adverse environmental conditions is of potential value for improving rhizobial inoculants and efficiency of symbiotic nitrogen fixationBakterija tla, Sinorhizobium meliloti važna je u poljoprivrednoj proizvodnji zbog sposobnosti fiksacije atmosferskog duÅ”ika u simbiozi s lucernom koja je vrlo vrijedna krmna kultura. Glavni cilj ovog istraživanja bio je procijeniti otpornost autohtonih sojeva S. meliloti na stresne uvjete okoliÅ”a. Najprije je genotipski karakterizirano dvadeset sojeva rizobija, izoliranih iz razliÄitih regija u Hrvatskoj, kako bi se procijenila raznolikost unutar prirodne populacije. Ispitivanje otpornosti na stres provedeno je u cilju odabira autohtonih sojeva rizobija otpornih na nepovoljne uvjete u tlu. Ispitivan je rast sojeva pri razliÄitim pH vrijednostima, temperaturama, koncentracijama NaCl-a i teÅ”kim metalima. Rezultati genotipizacije 16S rDNA PCR / RFLP analizom pokazali su da 17 izolata pripada vrsti S. meliloti, dok je primjenom RAPD i ERIC-PCR metode utvrÄena znaÄajna genetska raznolikost meÄu autohtonim sojevima rizobija. UtvrÄena je veÄa otpornost autohtonih sojeva S. meliloti na nepovoljne uvjete rasta u usporedbi s referentnim sojem. VeÄina sojeva rasla je na temperaturama viÅ”im od optimalnih i toleriralo je i kiselo i alkalno okruženje. UtvrÄeno je da autohtoni sojevi podnose ekstremno visoke koncentracije NaCl. Bolje razumijevanje prilagodbe rizobija na nepovoljne uvjete okoliÅ”a važna je u svrhu poboljÅ”anja inokuluma i uÄinkovitost simbiozne fiksacije duÅ”ik