Piriformospora indica: A Helper Endophytic Fungus in Enhancing Growth and Nutrient Status in Crops

Abstract

Many microorganisms including root endophytes establish symbiotic relationships with their host plants and play a crucial role in maintaining better soil health and plant growth. Most of the crops are responsive to manures and fertilizers; however, the indiscriminate use of inputs especially chemical fertilizers can result in adverse environmental impacts which may degrade soil health and quality, affect rhizosphere micro-environment and cause nutrient imbalances. These adverse effects can be reduced by adopting new microbial-based technological practices, especially the use of biofertilizers, which are renewable and ecofriendly alternatives to chemical fertilizers that promote plant growth by enhancing the availability of plant nutrients. Piriformospora indica, a helper mycorrhiza like endophytic fungus has received immense importance over the preceding decades because of its ability to efficiently promote plant growth through enhanced nutrient uptake, bioactive substance accumulation, crop protection from pest and disease attack. Additionally, P. indica also helps to improve plant resistance to biotic stresses such as bacterial, fungal, viral and nematode diseases and abiotic stresses like drought, salinity and heavy metal toxicity.  Apart from the fungal biomass, derivatives of P. indica such as cell wall extract as well as culture filtrate also acts as an excellent source for plant growth promotion. Here, we explore the mechanisms involved in P. indica mediated growth promotion as well as biotic and abiotic stress mitigation which includes enhanced nutrient acquisition and its translocation, increased efficiency of photosynthesis and modulation of phytohormones involved in growth and development. With the increasing demands for safer agricultural products and foods without the use of chemical fertilizers and pesticides, this paper also identifies research needs for making suitable biocontrol or biofertilizer formulations by utilizing the functional abilities of P. indica.