Fungal Secondary Metabolites and Bioactive Compounds for Plant Defense

Abstract

Crop diseases are among the main constraints in adequate production of food crops and impose significant losses to global agricultural system. Considerable crop losses are caused by phytopathogens which need to be controlled in order to maintain the quality of food and feed around the world. In agricultural practices, chemical pesticides are mainly used to control plant diseases. However, their applications are costly and they pollute the environment, causing hazard to human and animal health. One of the most effective strategies to improve plant health is the biological control of plant pests and pathogens using microbial bioactive compounds. Numerous microorganisms, including fungi, produce secondary metabolites and bioactive molecules which affect the interactions of plants with their pathogens. These fungi can symbiotically colonize plants and produce bioactive secondary metabolites that can effectively suppress phytopathogens or stimulate plant growth. Fungal secondary metabolites are involved in a variety of mechanisms for plant defense, which involve direct antibiosis against damaging organism, triggering systemic plant defense activity against them, and enhancing plant nutrient uptake. Important fungi that produce biocontrol secondary metabolites against fungal and bacterial phytopathogens, nematodes, and other pests, include Trichoderma spp., Neotyphodium spp., Phomopsis spp., Paecilomyces lilacinus, and Pochonia chlamydosporia. In this chapter, three important groups of fungal bioactive secondary metabolites are discussed in detail with their sources, synthesis, and their role in the plant defense mechanisms against plant pathogens.