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Pathobiome and microbial communities associated with forest tree root diseases [Chapter 15]

Formally Refereed

Abstract

Soil microbial communities occupy the most biologically diverse habitats in the world. A single gram of soil can support more than several thousand fungal taxa near the root rhizosphere (Buée et al., 2009). As mentioned in other chapters in this book, many factors can influence the microbial communities associated with tree leaves, stems, and roots. Differences in host species (Prescott and Grayston, 2013), cultivar type within a species, soil type, physiological status of host, and pathogen presence can influence variation in microbial communities (Costa et al., 2007; Aira et al., 2010; Chaparro et al., 2013; Yuan et al., 2015). Ecological balance within the associated microbial community is critical for plant health, especially in the rhizosphere, and disturbances can cause imbalances within the microbial communities. Previous studies have documented that beneficial microbial relationships can enhance seedling vigor, seed germination, plant development, and plant growth that lead to higher plant productivity, whereas attacks by plant pathogens can alter the microbiome structure, functionality, and activity (Trivedi et al., 2012). Beneficial microbial interactions can lead to improved host resistance against pathogenic bacteria and fungi. For example, beneficial microbial taxa can secrete various allelopathic chemicals and toxins that provide the plant with protective barriers that impede plant pathogens. The rhizosphere has been shown to contain diverse and complex biological communities that encompass bacteria, fungi, oomycetes, and many other microorganisms, such as archaea, nematodes, and viruses (Raaijmakers et al., 2009). Other tree organs, including leaves, branches, and stems, are also known to contain a diverse suite of microbial taxa, but overall diversities are typically lower than those found in soils (Baldrian, 2017). Although microbial diversity can vary greatly, pathogens can greatly affect microbial communities. This chapter will briefly review the concept of pathobiome, how microbial communities protect against plant disease, and various changes that can occur within microbial communities in the presence of plant pathogens. Because these research topics are recently developing in forest sciences, examples will be derived from cropping systems as diverse as wheat, apples, and forests. As expected, microbial communities can be vastly different within annual vs. perennial cropping systems; however, the influence of plant pathogens on microbial communities and their ecological roles have been documented primarily in diverse cropping systems.

Keywords

soil, pathobiome, microbial communities, forest tree root diseases, plant pathogens

Citation

Stewart, Jane E.; Kim, Mee-Sook; Lalande, Bradley; Klopfenstein, Ned B. 2021. Pathobiome and microbial communities associated with forest tree root diseases [Chapter 15]. In: Asiegbu, Fred O.; Kovalchuk, Andriy, eds. Forest Microbiology - Tree Microbiome: Phyllosphere, Endosphere, and Rhizosphere, Volume 1. London, UK: Academic Press, Elsevier, Inc. p. 277-292.
https://www.fs.usda.gov/research/treesearch/62774