Lifting the veil over mysterious desert truffles: Terfezia’s ecology and diversity towards cultivation

Developing below the soil surface, desert truffles are hard to find. Recently, researchers of the University of Évora updated the number of known species of the desert truffle genus Terfezia occurring in Portugal from three to ten species. They thoroughly characterized their ecological preferences, adding new knowledge on Terfezia’s cryptic lifestyle. These findings are of major importance, as desert truffles have a high economic value. The study was published in the open-access journal MycoKeys.

In a caring, symbiotic relationship, mycorrhizal fungi live and feed in the roots of specific plants, while providing water and nutrients to their ‘companion’. In arid and semi-arid environments, mycorrhization processes are essential to the survival of both plants and fungi. Moreover, the fungus’ hyphal network, which spreads within the soil connecting several plant individuals, is of utmost importance to enhancing soil quality and fertility.

Researchers of the University of Évora in Portugal, led by biologist Celeste Santos e Silva, worked on Terfezia fungi, the most diverse and species-rich genus among desert truffles. Their study, published in the open-access journal MycoKeys, might prove particularly valuable to rural populations in the Mediterranean basin, where desert truffles, highly valued in local markets, are an important food source. Increasingly turning into an exquisite component of the Mediterranean diet, Terfezia products can also be very profitable. Furthermore, these fungi are essential for soil conservation, preventing erosion and desertification.

Desert truffles.

After 8 years of exhaustive field exploration in search of desert truffles and many hours in the molecular biology lab, the researchers noted some previously unknown trends in the ecology of Terfezia species. They recorded seven species that were new to Portugal, including two that are new to science – Terfezia lusitanica and Terfezia solaris-libera. This brings the number of Terfezia species known to be growing in the country to ten. Particularly important was the discovery of a broader ecological range for many of the studied species (e.g. Terfezia grisea). Adding valuable information about their possible hosts, symbionts and ecological constraints, these findings help open new opportunities for truffle cultivation.

“It is very difficult to identify all specimens given that the Terfezia species look so much alike, and molecular biology was absolutely fundamental here”, explains the researcher. “The technique was essential to update and solve problems about their taxonomy and the relationship between the species in the genus.”

Furthermore, the discoveries are also expected to positively impact the local communities by stimulating agriculture produce, business and even employment. 

Desert truffle production explained. Video by University of Évora

Knowledge gained in this research about the conditions in which different Terfezia species grow is an important step to desert truffle cultivation: the fungi are hard to find in the wild, which is why it would make a big difference – including financially – for local communities if they figure out a way to grow truffles themselves.

Within the project “Mycorrhization of Cistus spp with Terfezia arenaria (Moris) Trappe and its application in the production of desert truffles” (ALT20-03-0145-FEDER-000006), the researchers took a step forward towards achieving mycorrhizal association of desert truffles with perennial plants (rock roses), which would allow their mass production for various sectors such as food, medicine and soil recovery. This new form of production, assures the MED researcher and leader of the project, “will make it possible to create more jobs, reversing the current trend towards desertification in rural areas, while being a great tool for ecosystem recovery and restoration”.

Research article:

Santos-Silva C, Louro R, Natário B, Nobre T (2021) Lack of knowledge on ecological determinants and cryptic lifestyles hinder our understanding of Terfezia diversity. MycoKeys 84: 1-14.

Long-distance survival: Effects of storage time and environmental exposure on soil bugs

Contaminated soil frequently arrives at the borders through transported items, and is widely recognised as a vector for non-native species, potentially threatening the local agriculture, horticulture and natural ecosystems. However, although soil is the target of management practices that aim to minimise the spread of invasive alien species, crucial knowledge of the biosecurity hazards that can accompany transported soil is currently lacking. While not much is known about the relative survival rates of the transported soil organisms, nor about their establishment probabilities, this information is essential to support optimal policy and management decisions.

soil-trays-on-top-of-research-sea-containersA recent study, led by Mark McNeill from AgResearch’s Biosecurity and Biocontrol team at Lincoln, New Zealand, and published in the open access journal NeoBiota, shows that biosecurity risks from soil organisms are to increase with declining transport duration and increasing protection from environmental extremes. The scientists sought the answer of a simple question – are soil organisms still risky after a year in the sun?

To find out, Mark and his team collected soil from both a native forest and an orchard and stored it on, in and under sea containers, as well as in cupboards. They tested it after three, six and twelve months for bacteria, fungi, nematodes and seeds.

“Soil can carry unwanted microbes, insects and plants, and this study showed that some died faster when exposed, than when protected in a cupboard. This work shows some of the risks presented by soil contamination,” Mark says.

“The results showed that viability of certain bacteria, nematodes and plants declined over 12 months, irrespective of soil source and where the soil was stored. But mortality of most organisms was higher when exposed to sunlight, moisture and desiccation than when protected,” he explains. “However, bacterial and fungal numbers were higher in exposed environments, possibly due to ongoing colonisation of exposed soil by airborne propagules.”

“The results were consistent with previous observations that organisms in soil intercepted from seaports tend to carry less bugs than soil found on footwear,” McNeill notes.

img-1-real-world_contaminated-footwear-2“The research also raised wider questions, because some results were unexpected, including trying to understand why the microbe numbers went up and down like they did in the soil sitting on the sea containers when everything else died off. Was it the circle of life or just new microbe migrants creating new populations?

“We hope that the work will be useful for plant quarantine authorities to assess the risk presented by transported soil based partly on where the soil is found and the age of the soil. This would help authorities to optimally allocate management resources according to pathway-specific risks. Importantly, the study will assist in the development of recommendations for increasing management efficiency and efficacy at national borders.”



Original source:

McNeill MR, Phillips CB, Robinson AP, Aalders L, Richards N, Young S, Dowsett C, James T, Bell N (2017) Defining the biosecurity risk posed by transported soil: Effects of storage time and environmental exposure on survival of soil biota. NeoBiota 32: 65-88.