Mechanistic Insights into Fluoride Stress Mitigation in Vigna mungo: The Interplay Between Host Genotype and Bradyrhizobium Symbiosis

Abstract

Fluoride (F) toxicity in soil is a growing agricultural challenge that severely limits the growth and nitrogen-fixing potential of pulses like black gram. This study provides mechanistic insights into how Bradyrhizobium symbiosis alleviates stress and investigates the role of host genotype in this protective relationship. By evaluating tolerant and sensitive blackgram genotypes under gradients, we observed that fluoride exposure triggers oxidative damage and disrupts nodulation. However, Bradyrhizobium inoculation significantly mitigated these effects by enhancing the antioxidant defense system (SOD, CAT, and APX). The tolerant genotype exhibited a more robust synergy with the microsymbiont, suggesting that the effectiveness of the symbiosis is governed by the host’s genetic architecture. These results highlight the biological buffering capacity of Bradyrhizobium and suggest that integrating specific plant-microbe combinations is a viable strategy for sustainable pulse production in fluoride-contaminated soils.