Exploiting the interactions between fungal antagonists, pathogens and the plant for biocontrol

Abstract

The soil community supports an enormous variety of biological interactions among its living inhabitants,which include those occurring between animals, insects, microorganisms and plants. Some of the most commonly found soil microbes belong to different species of Trichoderma and function as antagonists of phytopathogens, thus protecting plants and reducing disease incidence in many different soil types. Together with other species, such as Pseudomonas spp., Bacillus spp., Coniothyrium spp., Pythium spp. etc., these highly interacting microbes have been extensively studied and commercially marketed mainly as biopesticides/biofertilizers and soil amendments, all containing live cells. Trichoderma spp. are also known to produce many different bioactive compounds, including dozens of cell wall degrading enzymes, and thus their biodegradation by-products, hundreds of antibiotics and many others still uncharacterized but highly reactive molecules. In fact, the broad spectrum biological effects of the relative fungal extracts suggest their use as alternatives to or additives with live microbes in diverse agriculture and industrial applications, including plant/fruit protection and food processing. These mixtures of fungal compounds can be easily produced at an industrial level and effectively applied to enhance antimicrobial activity of common fungicidal compounds, as well as activate or stimulate biocontrol agents and plant resistance to pathogen attack. Studies into the complex three-way relationship that Trichoderma establishes with the plant and pathogen are revealing mechanisms involved in partner recognition and the molecular cross-talk used to maintain the stable association that provides benefits both for the fungal antagonist and the plant. © 2007 Springer.