Arbuscular mycorrhizal influence on oxidative stress in French bean (Phaseolus vulgaris) under drought conditions

We investigated the antioxidant response in French bean (Phaseolus vulgaris) seedlings in a symbiotic interaction with Arbuscular mycorrhiza fungi (AMF) under drought and studied both shooting and rooting tissues to detect the targeted tissue for AMF effects induced under drought. AMF and Non-AMF French bean seedlings were grown under control (well-watered: WW) and drought-stress (DS) conditions to study their tolerance response by assessing various physiological and biochemical parameters. AMF plants appeared to be sheltered from drought as seen by their higher leaf water potential and production of shoot-biomass. The AMF shoots accumulated less proline than those of non-AMF, while the opposite was observed in roots. Also, in DS AMF plants, lipid peroxides were 60 percent lower than in DS non - AMF plants. However, no significant correlation could be established between antioxidant enzyme activity and the low lipid oxidative damage in AMF plants due to which it appears that the symbiont fungus enhances osmotic adjustment first in the root system, which promotes a water potential gradient that favors entry of water into roots from the soil. This enables increased leaf water potential in DS-AMF plants keeping plants sheltered from oxidative damage, and all these collective effects increase the drought hardiness of seedlings.