Small genome of the fungus Escovopsis weberi , a specialized disease agent of ant agriculture

Abstract

Many microorganisms with specialized lifestyles have reduced genomes. This is best understood in beneficial bacterial symbioses, where partner fidelity facilitates loss of genes necessary for living independently. Specialized microbial pathogens may also exhibit gene loss relative to generalists. Here, we demonstrate that Escovopsis weberi, a fungal parasite of the crops of fungus-growing ants, has a reduced genome in terms of both size and gene content relative to closely related but less specialized fungi. Although primary metabolism genes have been retained, the E. weberi genome is depleted in carbohydrate active enzymes, which is consistent with reliance on a host with these functions. E. weberi has also lost genes considered necessary for sexual reproduction. Contrasting these losses, the genome encodes unique secondary metabolite biosynthesis clusters, some of which include genes that exhibit up-regulated expression during host attack. Thus, the specialized nature of the interaction between Escovopsis and ant agriculture is reflected in the parasite’s genome.

Genome Analysis of Two Pseudonocardia Phylotypes Associated with Acromyrmex Leafcutter Ants Reveals Their Biosynthetic Potential

“…We also identified several BGCs appearing on DNA with similarity to plasmids, suggesting that Pseudonocardia associated with fungus farming ants may be inclined to pass around BGCs via horizontal gene transfer. Genome sequencing recently revealed that Escovopsis weberi has a reduced genome, most likely due to its role as a parasite on the fungal garden of attine ants (de Man et al, 2016). Despite loss of many genes, however, E. weberi has maintained a number of genes involved in secondary metabolite biosynthesis, suggesting that colony-life in fungus-growing ants are characterized by ongoing evolutionary arms races between microbial symbionts.…”

Ericoid mycorrhizal fungi and their genomes: another side to the mycorrhizal symbiosis?

“…For example, extensive gene loss was found in populations of the cyanobacterium Prochlorococcus highly specialised to narrow ecological niches (Dufresne et al, 2005). In fungi, a reduced genome and gene content was found in Escovopsis weberi, a highly specialised mycoparasite of ant-cultivated fungi, when compared with unspecialised mycoparasitic species in the closely related genus Trichoderma (De Man et al, 2016), suggesting that gene loss in E. weberi is connected to its narrow niche and highly specialised lifestyle. Gene loss is very well documented for microbes that specialised as obligate biotrophs, with extremely reduced genomes being reported for bacteria living in association with different eukaryotes (McCutcheon & Moran, 2012).…”

Secondary Metabolites from Escovopsis weberi and Their Role in Attacking the Garden Fungus of Leaf‐Cutting Ants

“…E. weberi degrades the hyphae of L. gongylophorus before direct physical interaction, suggesting that the pathogen secretes toxins and/or enzymes that can break down host mycelium before contact occurs . The recently sequenced E. weberi genome encodes for a variety of secondary metabolite biosynthesis gene clusters . Some of these gene clusters including polyketide synthase gene clusters were significantly up‐regulated when growing with L. gongylophorus .…”

“…The recently sequenced E. weberi genome encodes for a variety of secondary metabolite biosynthesis gene clusters . Some of these gene clusters including polyketide synthase gene clusters were significantly up‐regulated when growing with L. gongylophorus . Moreover, crude extracts of several Escovopsis species were reported to inhibit the growth of L. gongylophorus .…”