Rhizobial strain involvement in plant growth, nodule protein composition and antioxidant enzyme activities of chickpea-rhizobia symbioses: modulation by salt stress.

Mesorhizobium ciceri, Mesorhizobium mediterraneum and Sinorhizobium medicae strains showed different symbiotic performances when inoculated to chickpea (Cicer arietinum L., cv. chetoui) at unstressed conditions and under salt stress. The analysis of nodular proteic composition and antioxidant enzyme activities revealed a polymorphism of patterns on SDS and native PAGE suggesting a potential dependence on the bacterial partner. Salt effect was analysed on plant growth, nitrogen fixation and antioxidant enzymes. M. ciceri, the most efficient strain, seemed to allow a best tolerance to chickpea plants under salt stress. This constraint did not affect the nodular superoxide dismutase (SOD, E.C. 1.15.1.1) activity of the symbiosis implicating the latter strain. This symbiosis showed the least decrease for the nodule protein level and the catalase (CAT, E.C. 1.11.1.6) activity, and the highest increase of peroxidase (POX, E.C. 1.11.1.7) activity that seemed to be related with the tolerance to salt.