Diversity and distribution of arbuscular mycorrhizal fungi in different salinity gradients of salt affected soils

Salt stress is one of the major environmental constraints for plant growth. Increasing salinization of soil induces hyperosmotic and hyperionic stress in plants due to accumulation of Na+ ions, which disturbs the normal metabolism of plants. Isolation and diversity analysis of native Arbuscular Mycorrhizal Fungi (AMF) from different gradients of saline soils collected from two salt affected soils of Karnataka viz., Gangavathi and Ugar Khurd was carried out. A total of Sixty one AMF isolates were isolated from the above two mentioned salt affected soils. Later it was identified that they belonging to three genera viz., Glomus, Acaulospora and Scutellospora by morphological characterization. The highest diversity was observed in Gangavathi habitat compared to Ugar Khurd in every diversity analysis measure (Shannon - weiner diversity index, Margalef’s index of species richness and simpon’s dominance index). Rapid In vitro screening were performed for evaluating early root colonization, antioxidant activities and biomass increasing ability of isolated AMF in different salinity levels (EC ranging 4 dS m-1, 6 dS m-1 and 8 dS m-1). The results of the screening indicated that the wheat plants which received UASDAMF SL27 exhibited high peroxidase activity (5.32, 5.36 and 6.04 U mg-1 protein at 4 EC, 6 EC and 8 EC respectively), followed by UASDAMF SL 11(5.02, 5.10 and 6.35 U mg-1 protein) and UASDAMF SL 31 (5.02, 5.09 and 6.04 U mg-1 protein). Therefore, it is evident from the results of the present study that application of AM fungi enhanced the activity of antioxidant enzymes in plants against the oxidative stress and improves the tolerance of plant to salinity stress.