ABSTRACT
Fungi play a central role in many soil microbiological processes, influencing soil fertility, decomposition, cycling of minerals and organic matter, plant health, and nutrition. Fungi are immensely diverse, both structurally and functionally, and have adopted different trophic strategies, occurring as saprotrophs, symbionts, and pathogens. This chapter reviews the main groups of fungi and fungus-like organisms inhabiting soil together with their general structural and functional features. Chytrids are considered to be the most ancient of the presently existing fungi. The chytrids are unique among the true fungi in that they are able to produce motile, flagellate zoospores, which typically have a single posterior, whiplash flagellum. Similar to the chytrids, the group formerly referred to as Zygomycetes has been found by DNA-based phyogenetics to consist of several separate lineages, not united by a common ancestor. The chapter discusses the Glomeromycota, in particular in relation to mycorrhizal symbiosis and the taxonomy and evolution of the fungi.
