Licorice (Glycyrrhiza glabra L.), is an herbaceous perennial and has been used as a flavoring agent in foods and medicinal remedies for years. Piriformospora indica, as an endophyte Mycorrhizal-like fungus, promotes the growth and survival of plants belonging to a number of species when exposed to various abiotic stresses, including drought and salinity stress. Drought stress is a major constraint of crop productivity. The goal of this research was the study of P. indica potential to colonize the roots of the licorice plant and to enhance growth and photosynthesis capacity under drought stress. This study was done as a factorial experiment in a completely randomized design with three replications and was conducted in the greenhouse of Malayer university (Malayer). The experimental factors included three fungal levels (inoculated with spore and mycelium and non-inoculated) and two drought levels (F.C., 50% F.C.). The results demonstrated that P. indica, promotes growth and confers drought resistance. Inoculation of the plant with P.indica increased the biomass of licorice plants, as in inoculated plants under drought stress total shoot and root dry weight was increased. The results showed that the chlorophyll and carotenoid contents of P. indica-inoculated licorice leaves were also higher than those of the uninoculated controls in drought stress. Higher chlorophyll and carotenoid content and thus photosynthesis rates might accelerate carbohydrate synthesis and thus growth of Glycyrrhiza glabra. These results suggest that P. indica is a helpful symbiont for promoting licorice growth and drought resistance [1, 2].
