Durga P. Panigrahi,Anubha Sagar, Shailu Dalal and Gursharn S. Randhawa
In the present study symbiotic abilities of two rhizobial strains were studied under arsenic stress. The rhizobial strains were isolated from the root nodules of alfalfa and cowpea plants grown in local agricultural fields and designated as Sinorhizobium sp. DP10 and Rhizobium sp. DP99 after 16S rDNA study. The arsenic resistance in these strains was tested in both liquid and solid mannitol salt yeast extract media. The presence of ars operon was confirmed by amplification of arsC genes through PCR using degenerate primers. Their symbiotic efficiencies under arsenic stress (1 and 5 mg/L) were studied by inoculating them onto their respective host plants. It was found that the plants were able to tolerate 1 mg/L of arsenic but got affected drastically at 5 mg/L arsenic level as evident from drastic reduction in mean dry weight, nodule number, total chlorophyll content, nitrogenase activity, shoot nitrogen content and activities of antioxidant enzymes.
