Termitomyces: exploring the world’s most mysterious mushroom (original) (raw)
Termitomyces for sale at the Mu Shui Hua Wild Mushroom Market in Kunming. Photo: World Agroforestry/Samantha Karunarathna
Researchers are readying to shine light on the world’s ‘dark matter’ — fungi — and expect surprising results.
The world’s biodiversity never fails to astonish. Nowhere is this more evident than in Southeast Asia and Africa, home to some of the most miraculous organisms to inhabit our planet. While the sheer physicality of many large animals found in the regions may captivate onlookers, some of the more baffling case studies from nature are right beneath our feet: termites and the fungi they actively farm.
Their homes are engineering marvels. Mounds can reach as high as 6 metres, dotting landscapes like extraterrestrial skyscrapers. These complex architectural structures are thought to contain microclimates carefully calibrated by worker termites in response to temperature fluctuations. Other functions, though, remain largely unknown.
That’s not all. It turns out that some termite species, such as those in the genus Macrotermes, might even be the world’s oldest farmers: fungus farmers, that is. New research suggests the practice began upwards of 25 million years ago and continues to this day.
Farming systems vary among species. In general, after a queen gives birth to her first workers, they set out in search of spores belonging to a particular genus of fungi called Termitomyces. Afterwards, they are brought back and deposited in a special cultivation chamber called the ‘comb’. The termites then excrete partially digested plant material into the soil, providing essential nutrients for the fungus to grow. Spores sprout hyphae, which function as the ‘roots’ of the fungi, and digest the plant matter provided by the termites, converting it to sugar, which is then consumed by the termites. A great example of circular agriculture! In addition, some Termitomyces species also possess enzymes that can degrade lignin, an organic substance particularly tricky to break down. The microbial interactions in the gut that allow termites to digest the degraded lignin still remain unclear, though.
An interdisciplinary team of ICRAF mycologists, soil biologists and entomologists at the Kunming Institute of Botany, Chinese Academy of Sciences is answering the call to find out more. The team hopes to shed light on these complex processes. Moreover, the Termitomyces fungus produces edible mushrooms and understanding the science behind their growth could lead to cultivation under artificial conditions.
The rewards for domesticating Termitomyces mushrooms are considerable. These mushrooms (‘jizong’ in Chinese) are wildly popular in Asia and Africa, where they are known for their nutritious value, medicinal properties and delicious taste. Since they are only gatherable in the wild during the rainy season, demand far exceeds supply. In addition, trickle-down effects may follow, as they are typically gathered by rural community members. If we can comprehensively understand the ecological mechanisms behind the co-evolution of termites and this fungus, it may allow locals to farm their own mushrooms, boosting household incomes.
‘We have two main goals,’ said Professor Peter Mortimer, leader of the project. ‘One, to shine a light on the largely unknown relationship between termites and fungus, examining the specific mechanisms involved in their symbiosis. Two, we want to sequence the whole genomes of different Termitomyces species from Asian and Africa and compare which genes control certain functions. We hope to establish a protocol for their successful cultivation, something that has eluded mushroom growers thus far.’
Termitomyces for sale at the Mu Shui Hua Wild Mushroom Market in Kunming. Photo: World Agroforestry/Samantha Karunarathna
However, there is no single instance of successful lab cultivation of Termitomyces. Termite-maintained ‘fungi gardens’ represent an especially unique node in the web of global biodiversity. In fact, most termite species rely upon protozoa in their gut to assist in the digestion of cellulose and do not require mutualistic partnership with other organisms. There are accordingly few examples in nature to study. In addition, little is known about microbial and enzymic interactions as well as the genetic composition of the few species that do engage in fungal farming.
The task clearly presents several steep challenges. ICRAF researchers remain optimistic, though. Some species have been transported to the lab from Africa to be sequenced, with more on the way. Sequencing multiple species will allow us to better utilize the whole genome. Decoding their genetic information will play an important role in understanding what genes control for important stages of development, such as the emergence of fruiting bodies.
‘We have several unique advantages,’ said Samantha C. Karunaratha, ICRAF mycologist. ‘We have decades of combined experience studying mushrooms in our team. Also, our team is composed of mycologists, ecologists, molecular biologists and entomologists. It is quite rare to find such an interdisciplinary team working on a project like this.’
Each team member brings expertise to a critical aspect of the project and preliminary fieldwork has already begun. Teams have scoured the local wild mushroom markets of Kunming, the capital of Yunnan Province, for Termitomyces species. Specific sites in Yunnan have already been selected and mapped for Termitomyces and soil collection, including Pu’er, Jinghong and Lincang. They cluster at the border with Myanmar across the Upper Mekong River Basin. Data loggers will be used to record conditions in natural habitats.
Asanka Bandara demonstrates how to add mushroom spawn to sterilized growing bags. Photo: World Agroforestry
ICRAF is no stranger to this tropical region. In the past, researchers have carried out research and training in towns and villages dotting the landscape. Its hills teem with biodiversity and unknown fungi awaiting discovery.
Species from the genus are slow-growing and can take up to two months to be successfully cultured. The project is thus long term in vision. Team members will also be doing focused social-study impact assessments on how to enhance the value chain for mushrooms in the region and connect local producers with socially responsible consumers.
Though past fieldwork has yielded promising results, we continue to know little or even nothing about the vast majority of fungal species populating our planet. Fungi are the ‘dark matter’ of terrestrial life: they seem to play critical roles throughout global ecosystems but we still know little about them. The team intends to use this Termitomyces research to illuminate a small patch of this dark matter.
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