Trichoderma: A Biological Weapon for Managing Plant Diseases and Promoting Sustainability

Trichoderma is a genus of asexually reproducing fungi that is present in all types of soils. Recent discoveries show that they are opportunistic, avirulent plant symbionts, as well as being parasites of other fungi. At least some strains establish robust and long-lasting colonizations of root surfaces and penetrate into the epidermis and a few cells below this level. They produce or release a variety of compounds that induce localized or systemic resistance responses. These root-microorganism associations cause substantial changes to the plant proteome and metabolism. Plants are protected from numerous classes of plant pathogen by responses that are similar to systemic acquired resistance and rhizobacteria-induced systemic resistance. Root colonization by Trichoderma spp. also frequently enhances root growth and development, crop productivity, resistance to abiotic stresses and the uptake and use of nutrients. As most of the crops are infected by the soil borne plant pathogens that primarily attack the vulnerable seeds or seedlings, the Trichoderma can be applied directly to target area, i.e., to seeds or seedlings and a single application using an existing delivery system (seed treatment, biopriming, furrow treatment) can significantly reduce crop losses. A number of successful products based on different species of Trichoderma have been commercialized in India and elsewhere. Whatever the limitations these Trichoderma products may have, it can be addressed by enhancing biocontrol through manipulation of the environment, accurate strain identification by molecular approach, using mixtures of beneficial organisms, physiological and genetic enhancement of biocontrol mechanisms, and manipulation of formulations. In some instances, other alternative methods that alone do not provide adequate protection may be integrated with application of biocontrol agents to provide additive or synergistic effects. This review tries to present the approaches adopted by researcher all over the world.