Fungal Genes and Metabolites Associated with the Biocontrol of Soil-borne Plant Pathogenic Fungi

Abstract

This handbook compiles authoritative information about fungal metabolites and their chemistry and biotechnology. The first in the reference work series “Phytochemicals”, and written by a team of international expert authors, this book provides reference information ranging from the description of fungal natural products, over their use e.g. as anticancer agents, to microbial synthesis, even spanning to the production of secondary metabolites on industrial scale. On the other hand it also describes global health issues related to aflatoxin production in foods and agriculture, including perspectives for detoxification. The handbook characterizes different compound classes derived from fungal secondary metabolites, like ergot alkaloids and aflatoxins. The discussion puts a special emphasis on how potentially useful compounds can be obtained and what applications they can find, on the one hand, and how potential dangers can be encountered on the other hand. The comprehensive chapters in this handbook will thus appeal to readers from diverse backgrounds in chemistry, biology, life sciences, and even medicine, who are working or planning to work with fungal (secondary) metabolites and their application. They provide the readers with rich sources of reference information on important topics in this field. The first authoritative summary and reference work on fungal (secondary) metabolites, their chemistry and biotechnological use and applications Covering aspects from beneficial use, to potential health issues of fungal metabolites Reference information for readers from various backgrounds: chemists, biologists, life scientists, medical scienti The biocontrol of plant pathogenic fungi includes two complementary approaches depending on whether the aim is to control soil-borne or air-borne pathogenic fungi. In the first case, natural biotic interactions within the indigenous microflora should be stimulated to regulate inoculum density and the infectious activity of pathogen populations. This strategy can be enhanced by inoculating one or more previously selected biocontrol agents. In the second case, one or more previously selected biocontrol agents can be sprayed on plant foliage to interfere with the development of the targeted pathogen through different mechanisms involving particular enzymes or metabolites. Selecting the most effective biological control agents implies (i) knowing the mechanisms of their interactions with the pathogens and (ii) checking that the environment in which the biocontrol agent is introduced will permit the expression of these mechanisms. The common thread of this chapter is the impressive diversity of metabolites and proteins produced by fungi and involved in interactions between pathogenic and nonpathogenic fungi. Many metabolites and proteins were discovered empirically or by chance a few decades ago, and what we knew about them was they inhibited the growth of pathogenic models on agar medium. Fungi producing these metabolites were not well-known fungal species and were not used as biocon- trol agents. However, the demonstration of their intense metabolic activity paved the way for more investigations in this area and led to deciphering the mechanisms of interactions between fungal strains. Thus, in recent years a large number of enzymes, signal molecules, secondary metabolites, large-size proteins, as well as new metabolic pathways have been revealed by genomics, and it is now possible to understand why some strains can control a given pathogen more than others or stimulate plant defense reactions. To date, the most studied fungi include many strains of the genus Trichoderma but also the species Chlonostachys rosea, Coniothyrium minitans, Verticillium biguttatum, and the oomycete Pythium oligandrum. All of them are successfully used as biocontrol agents. This chapter does not aim to provide a comprehensive catalog, but rather to associate these metabolites and proteins to the modes of action involved in pathogen control. The state of the art presented in this review suggests promising prospects for rational, appropriate, and effective use of the biocontrol potential offered by the huge diversity of fungal metab- olites and proteins.