Differential effectiveness of Arbuscular Mycorrhizae in improving Rhizobial symbiosis by modulating Sucrose metabolism and Antioxidant defense in Chickpea under As stress

Arbuscular mycorrhizal (AM) fungi can improve nitrogen (N2) fixing potential of legumes under metalloid stress by enhancing nutrient uptake and modulating antioxidant defense mechanisms. Diversity among AM species in imparting metalloid tolerance highlights the importance of selecting best host-fungal combinations. Therefore, effectiveness of AM species: Rhizoglomus intraradices (Ri), Funneliformis mosseae (Fm), and Claroideoglomus claroideum (Cc) in improving N2 fixation was assessed in two differentially metalloid tolerant chickpea genotypes: HC 3 and C 235 under arsenate (AsV) and arsenite (AsIII) stress. Nodulation potential had a negative correlation with As, the impacts being more severe in C 235 than HC 3. AM species strengthened symbiotic process by enhancing availability of N, P and Fe to the nodules through increased soil enzymes activities. AM also accelerated the activities of sucrolytic enzymes in host nodules, for improved C accessibility to the bacterioids. Mycorrhization significantly increased the antioxidant enzyme activities as well as the concentrations of thiol derivatives. Ri was most efficient in improving functional efficiency of nodules, closely followed by Fm, with least positive impact of Cc, which could be related to their differential mycorrhizal colonizing abilities. Study highlighted importance of Ri inoculation for maximising the symbiotic efficiency of chickpea in As contaminated soils.