Title : Fungal diversity: Biotechnological exploitation in sustainable agriculture
Abstract:
Biodiversity, also called biological diversity, refers to the variety of life/ living organisms on our planet earth, including plants, animals, fungi and tiny microorganisms, that keep our ecosystems healthy and resilient. Biodiversity study includes the identification, describing and naming species, including their useful properties, across all habitats around the world. What grows where knowledge about where to find particular species in nature must have been key to the survival of humans throughout our evolution. Professor Alexandre Antonelll of Royal Botanic Gardens, Kew in 2023 stated", that to date, we have not been able to answer one of the most fundamental questions in plant and fungal diversity with confidence- namely, how many species are there globally and in different parts of the world fungi, the eukaryotic heterotrophs, occur as uni-to multicellular filamentous microscopic- to macroscopic organisms, across a board range of habitats- within soil or organic materials, in water, on rock, or on living and dead trees, including extreme environments, growing via absorptive nutrition. These elusive organisms, vital in ecosystem functioning, first appeared around 1.3 billion years ago, are currently considered as the 2nd largest kingdom of eukaryotes after animals. Global fungal diversity is estimated ranging between 2.5 million and 3.8 million with only 1,60,000 species described so far (Species Fungorum 2024), meaning that the vast majority are still undiscovered. Annually, mycologists describe under 3000 new fungal species and it would take 750-1000 years to fully describe the world' fungi at the current rate. Fungi are amazing organisms with the potential to be exploited biotechnologically in over 50 ways. For sustainable agriculture, they can be used in agricultural waste disposal (mycoremediation), controlling weeds (mycoherbicides) and soil borne pathogens (mycofungicides) and growth promoting hormones in enhancing crops production. Fungi, because of their ability to produce extracellular enzymes (cellulases, hemicellulases, xylanase and chitinase) can degrade/ decompose crop and forest residues, and has the potential to be exploited in reducing organic matter, conserving precious resources and reducing the generation of waste and greenhouse gas emissions, referred to as "circular economy". The adoption of 3Rs-reduce, reuse and recycle, strategy is highly significant to support sustainability efforts in agriculture, reduce pollution and support biodiversity. Two notable examples are: in situ compost production from parali using Trichoderma- based organo-decomposer; and Pusa decomposer, a consortium of eight fungi, developed by Pusa Institute (IARI), New Delhi, that helps paddy straw into compost within 20 days. There are over 10000 fungi known to cause diseases on plants- crops, vegetables, weeds, fruit and forest trees. Some of these diseases had been suicidal resulting in complete crop failures. Phytopathogenic fungal diversity is being exploited in developing eco-friendly bioherbicides/mycoherbicides - host specific microorganisms- based formulations for managing notorious weeds, and preferred over synthetic herbicides due to their potential health risks to humans, environment, plants, animals and pollinators. Over 23 mycoherbicides, mainly based upon the fungus Colletotrichum, a hemibiotrophic pathogen, has been developed globally. Several fungi are known to act as effective biocontrol agents (BCAs) against phytopathogenic fungi. Trichoderma spp. have been developed commercially as fungicides to control fusaria (wilts), Rhizoctonia, Sclerotium (root rots) and Pythium (damping off), as alternatives to synthetic fungicides. Trichoderma control plant pathogens via mycoparasitism, antagonism, competition or plant defence system induction. Most of the Trichoderma formulations are based upon T. harzianum, a soil borne saprophytic ascomycetous fungus, and are being used in several countries, including India for sustainable agriculture. In this presentation, the emphasis will be on what is biodiversity current status of fungal diversity, various ways of exploiting fungi industrially, especially in bioremediation of crop residues, and controlling weeds through mycoherbicides, and soil borne fungal diseases through mycofungicides.
