High diversity and low host-specificity of Termitomyces symbionts cultivated by Microtermes spp. indicate frequent symbiont exchange

Lennart J.J Van De Peppel,Duur K Aanen

doi:10.1016/j.funeco.2020.100917

Lennart J.J Van De Peppel, Duur K Aanen

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https://doi.org/10.1016/j.funeco.2020.100917

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Journal: Fungal Ecology	Publication Date: Mar 31, 2020
Citations: 12	License type: cc-by

Affiliation: Wageningen University & Research

Abstract

Abstract Fungus-growing termites (subfamily Macrotermitinae) live in an obligate mutualistic symbiosis with species of the fungal genus Termitomyces (Basidiomycota). Although the species that build large mounds are the most conspicuous, termites of the genus Microtermes construct large underground networks of tunnels connecting many fungus gardens. They are also the only entire genus within the Macrotermitinae in which vertical transmission of the fungal symbiont has evolved. To study patterns of genetic diversity in species of the genus Microtermes and their Termitomyces symbionts, we sampled at three different locations in South Africa and sequenced COI for the termites and ITS for the fungi. We discovered high genetic diversity in both termites and fungal symbionts but very low interaction specificity. This implies that frequent horizontal exchange of fungal symbionts occurs between species, despite vertical transmission across generations. We also estimated colony size based on termite haplotype and fungal genotype combinations and found indications that colonies may extend over large areas.

Highlights

Termites are a large and diverse insect group
In general we found termite and fungal symbiont diversity to be highest at locations EF and MO
Aanen et al (2007) found four species of Microtermes and six different CO1 haplotypes in South Africa

Summary

Introduction

Termites (order Isoptera) are a large and diverse insect group. They play an important role in ecosystem functioning as decomposers, especially in the tropics (Jouquet et al, 2011). The most conspicuous fungus-growing termites construct large epigeal mounds but other genera have subterranean colonies in which they farm their fungus. The termites grow their fungus on a special substrate called the fungus comb, which they build from primary feces consisting of plant material inoculated with asexual spores. They harvest the asexual fruit bodies which serve as a protein-rich food source, a source of additional digestive enzymes, inoculum for new fungus combs and a source of the essential amino acid tryptophan (Martin and Martin, 1978; Leuthold et al, 1989; Nobre and Aanen, 2012; Chiu et al, 2019)

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