The endophytic fungus Piriformospora indica increases nutrient uptake in plants and allows plants to survive under biotic and abiotic stresses. This fungus stimulates growth and seed production of plants and increases the secondary metabolite contents of medicinal plants. There is little information on cultivation of symbiotic fungi therefore the development of methods to the mass culture of symbiotic fungi is very importance for practical applications. The aim of this study was to reveal a simple culture medium to higher biomass production for this fungus. A comparison of YPG simple medium and Kafer Complex medium was carried out on the dry weight of fungus. Then Taguchi method was used to design experiments for medium optimization to determine the effect of four factors including glucose, yeast extract and peptone concentrations, and pH on the fungal biomass production in a non-continuous culture. Comparison of the growth curve of the fungus in both the Kafer and YPG media showed that P. indica growth was better and higher in YPG medium. After optimization of YPG medium, biomass production was reached to 19.3 g.L-1 in compared with the initial amount i.e.16.2 g.L-1. Our results suggested that YPG medium can be used as a suitable medium to P.indicaindustrial production for agricultural application, due to the higher biomass production of P. indica in YPG medium by 2.5-fold and its low cost in compare to Kafer medium.

By modifying plants at genetical, physiological and ecological levels, entophytic fungi as the most important soil microorganisms have a pronounced growth-promoting activity and also increase plant resistance to biotic and abiotic stresses. This research was undertaken to evaluate the potential of P. indica to increase barley (Hordeumvulgare L.) resistance to lead (pb). Therefore, a greenhouse experiment with two fungus treatments (non-inoculated and P. indica inoculated) and five levels of pb (0, 25, 50, 100 and 500 mg/kg) with three replications was conducted based on a factorial design. Measurement of shoot and root dry weight showed that the growth of P. indica-colonized plants at all levels of pb treatments was higher (P<0.05) than that of the corresponding controls. Also, chlorophyll concentration of inoculated plants with P. indica was superior to non-inoculated plants. In addition, the results showed that in contrast to the plant shoot, lead concentration in the root of P. indica-colonized plants was higher than the non-inoculated controls.

Abiotic stresses including salinity are the major limiting factors of growth and crop production worldwide. Microbial endophytes as the most important soil microorganisms, by modifying plants at genetical, physiological and ecological levels increase their yield per area unit and provide the possibility of crop production in saline and arid soils or climates with biotic and abiotic stresses. The endophytic fungus, Piriformospora indica has a pronounced growth-promoting activity and also increases plant resistance to environmental stresses including salinity, drought and plant pathogens. This research deals with the potential of P.indica to improve growth of barley (Hordeum vulgareL.) and increase its resistance to salt stress. The obtained results show that P. indica increases the biomass of aerial parts and root of inoculated plant in compared to the controls. In addition to plant growth promoting activity of P.indica, the obtained results of this research approved the effective role of this fungus to improve growth and yield of barley under salt stress conditions. Application of this fungus as a plant growth promoting agent in production of biological fertilizers and its wide utilization for crop plants plays an important role to reach the sustainable agriculture.

Heavy metal stress is one of the most important factors limiting the growth and yield of plants in many parts of the world. The fungus Piriformospora indica, as a mycorrhizal endophytic fungus, stimulates the growth of many plant species and also increases the resistance to biotic and abiotic stress. In this research, the interaction effect of P. indica and Cd on germination of fenugreek, also the interaction effect of P. indica and Cd in soil system were investigated on morphophysiological traits of fenugreek according to a factorial experiment based on completely randomize design (CRD) with 3 replication in two independent experiments. The results of interaction effect of P. indica and Cd on germination of fenugreek showed that Cd stress may give to plants allows germination, but increased in their concentration impaired the some seed germination indices of fenugreek. Also the results of the interaction effect of P. indica and Cd in soil culture showed that Cd stress reduced the most of measured morphological traits mean and increased the most of enzyme studied in fenugreek. According to these results, it seems that the fungus in addition to colonization of fenugreek also has an effect on its improvement in Cd stress.