ABSTRACT
Trichoderma spp. (perfect state, where known, belongs to the genus Hypocrea) represent a large group of fungi omnipresent in soil and in diverse ecosystems. Trichoderma reesei is the primary source of industrial cellulases and hemicellulases (Mach and Zeilinger 2003). Many species of Trichoderma are mycoparasites and some are rhizosphere/root colonizers. The mycoparasitic nature renders these fungi to be used as biofungicides. A large number of formulation products are available for commercial agriculture (Varma et al. 2007). Intimate association of Trichoderma spp. with plant roots and the benefi cial effects of such interactions have led
Trichoderma spp. to be known as “opportunistic avirulent symbionts” (Harman et al. 2004, Shoresh et al. 2010). The benefi ts of such interactions range from improved nutrients uptake to imparting immunity in plants to pathogens are driven by a nutritional relationships where Trichoderma use plant sucrose and in return enhance photosynthetic ability of plants (Vargas et al. 2008, 2009). Trichoderma spp. are also known for their ability to reduce oxidative damage to plants/seeds and negates effects of seed aging (Harman et al. 2006, Shoresh and Harman 2008, Matsouri et al. 2010). By virtue of improving root growth, these fungi also impart drought tolerance, in addition to improving plant nutrition (Altomare et al. 1999). Some strains are reported to produce phytohormones (like auxins) that help improving the plant biomass (Contreras-Cornejo et al. 2009). Trichoderma spp. also produce a large number of secondary metabolites that infl uence interactions with plants and other microbes. The advent of molecular genetics has improved our knowledge of details of interactions of Trichoderma with plants and other fungi. The purpose of this review is to highlight the mechanisms of such interactions at the genetic level.
