ABSTRACT
18Species of Trichoderma belong to one of the most useful group of microbes to have had an impact on human welfare in recent times. Trichoderma (teleomorph Hypocrea; Hypocreaceae, Hypocreales, and Ascomycota) spp. have had a major influence on agriculture too. Trichoderma spp. are one of the most plentiful fungal genera found in many ecosystems. They are most widespread and popular research tools as microbial inoculants that are largely used against several plant pathogenic fungi causing soil borne, foliar, and post-harvest diseases of plants. This is well reflected by the completion of whole genome sequencing of as many as seven species of Trichoderma by the Joint Genomic Institute (JGI) (Mukharjee et al., 2013). Having highly antagonistic and mycoparasitic potential in laboratory conditions, they have shown to reduce the severity of plant diseases by inhibiting plant pathogens in the soil. Trichoderma can have direct effects on plants, increasing their biomass and nutrient uptake, fertilizer use efficiency, seed germination, and stimulation of plant defenses by enhanced photosynthetic ability, against biotic and abiotic stresses and hence is a famous plant growth promoter. Some species can kill plant parasitic nematodes and have the potential to be used as bio-nematicides.
Most Trichoderma are endophytic plant symbionts. These changes alter plant physiology and may result in the improvement of nitrogen uptake, resistance to pathogen, photosynthetic efficiency, as well as abiotic stress tolerance. According to an estimate, about 60% of all the registered biofungicides worldwide are Trichoderma based with more than 250 Trichoderma-based formulations being commercially sold in India alone (Verma et al., 2007). Trichoderma strains interact with the plant by colonizing roots, establishing chemical communication, and systemically altering the expression of numerous plant genes.
So far major bottleneck with the use of Trichoderma is their uneven field performance. This is due to the fact that they are biotic agents. Their field performance depends upon a number of factors like, strain/ host selectivity, environmental conditions, inoculum density, method of delivery, and so forth. By far, application of Trichoderma both through seed and colonized compost is the most effective delivery system for the management of seedling and root diseases in different crops. Also they can help alleviate abiotic stresses in plants, including water deficit (drought), salinity, and temperature.
