Growing in the dark, foe or friend?
The National Collection of Fungi
There are more than 50 documented uses of fungi (Hyde, 2019) including being used as a source of food and nutraceuticals, in the making of beverages such as wine, beer and tea; a source of animal feed, and as an alternative for standard, chemical synthesis of phosphonates as biocatalysts. They also play an active role in environmental management as they can break down plastics and poly hydrocarbon pollutants. In the production of pulp, paper and textiles, complicated structures such as lignin are broken down and are used to produce biomass used as biofuel. In the food sector, we grow fungi as food in compost, use them for food coloring and flavoring and they are also used as a source of tourism income, named mycotourism (Buntgen, 2017). In this segment, however, we will focus on their dual contribution to the agricultural sector in South Africa.
As plant pathogens, the devastating impact of fungi on the world economy is well documented. In 2012, the journal Molecular Plant Pathology published a survey on the top 10 fungal plant pathogens. Not surprisingly the top candidate was the rice pathogen Magnaporthe oryzae as over one-half of the world’s population relies on rice as the main source of calories. Botrytis cinerea was in second place due to its broad host range and because it causes severe damage, both pre- and post-harvest. The impact of fungal plant pathogens derives from crop or yield loss; decreased quality of the plant or plant product; the costs of control and the need for continuous monitoring. Food contamination by fungi also have a social impact as The Food and Agriculture Organization has estimated that 25% of the world’s crops are contaminated with unacceptable levels of toxins produced by fungi.
In South Africa, the National Collection of Fungi (NCF) was established in 1905 with the mandate to study and document plant diseases in the then Union of South Africa. The first comprehensive list of agriculture associated fungi was published in 1950 by Ethel Mary Doidge who documented 1698 genera and 9496 species from across South Africa (Doidge, 1950). All the specimens used in this document are housed in the NCF. In 2000, the list was updated by Crous et al., and again the NCF dried fungorium collection (PREM) played a significant role, in providing data.
Specimens in the collection have been used in a variety of ways to support the agricultural industry in South Africa. The description of a new fungal species from pineapple enabled the country’s growers to distinguish the species recorded to occur in South Africa from the species that devastated the pineapple industry in Brazil (Jacobs et al., 2010). Similarly kikuyu poisoning of cattle in South Africa was shown to be caused by a different species than that reported from Australia (Botha et al., 2010), which assisted veterinarians to diagnose the disease effectively.
As part of an early warning system, fungorium specimens housed at the NCF for wheat brown rust, provided the opportunity to investigate the genetic development of populations using isolates collected between 1906 and 2010 (Labuschagne et al., 2021). Five sub-populations that survived between 21 and 82 years in the field, were found. While three of these could represent the original races that entered SA during European settlement, two appear to be recent exotic introductions into SA, most probably from other African countries. These results illustrated the importance of annual surveys to timeously, detect the presence of new virulent races that could threaten wheat production in SA. The diagnostics services support by the NCF, a Department of Agriculture, Land Reform and Rural Development (DALRRD) registered laboratory, further expands the support to early warning systems in South Africa by the certification of material for quarantine fungi, such as Tillitia indica (Karnal Bunt on wheat) and Ustilago maydis (Maize smut).
The role of fungi in agriculture is not restricted to causing plant diseases. Fungal antagonists used as biocontrol agents (BCAs) play a significant role in controlling pests, diseases and weeds globally. As an important component of sustainable crop production, fungi have several characteristics that make them suitable as BCAs. These include the direct penetrate through the insect cuticle or an increase in the mortality rates in a pest population. Against fungi BCAs ability to affect the survival or germination of the pathogen or competing with the pathogen for nutrients and/or space, induce resistance responses in the plant and/or promote plant growth render them an economic viable alternative to chemical control. Towards this end, the NCF entered into benefit sharing negotiations with BASF in 2018. The fungal strain, PPRI 5339, was purchased from the NCF and developed into a biocontrol agent by BASF, marketed as BroadBand®. It acts as a broad-spectrum, biological insecticide for effectively reducing target insects on vegetable crops.
Fungi and specifically mycorrhizae have also been commercial employed as biofertilisers worldwide. Fungal biofertilisers, which involve the use of selected fungal strains, are formulated to provide nutrients to the host plant and safeguard the crop against pathogens. As they have an ability to transform nutritionally important elements from non-usable to highly assimilable forms without deleterious effects on natural environment, they are an important component of integrated crop management. In this regard, the NCF serves as depository for commercial strains under the Budapest Treaty of which South Africa is a signatory.
The recent economic figures released by Statistics South Africa (StatsSA) show that agriculture was the only sector that posted a positive growth figure in the last quarter of 2020. Agriculture continues to be the redeeming feature of the South African economy even in trying times of economic contraction and the Covid-19 pandemic. The NCF’s contribution towards this sector spans over 116 years and should continue well into the future as new technologies are being employed to study its holdings.
References:
Botha, C.J., Truter, M., Jacobs, A., (2014). Fusarium species isolated from Pennisetum clandestinum collected during outbreaks of kikuyu poisoning in cattle in South Africa’, Onderstepoort Journal of Veterinary Research 81(1), Art. #803, 8 pages.
Büntgen, U., et al. 2017. New insights into the complex relationship between weight and maturity of Burgundy truffles (Tuber oaestivum). PLoSNE 12:e0170375. https://doi.org/10.1371/journal.pone.0170375
Crous, P. W., Phillips, A. J. L., Baxter, A. P. (2000). Phytopathogenic fungi from South Africa, 546 pp.
Doidge, E.M. (1950). The South African fungi and lichens to the end of 1945. Bothalia, 5: 1–1094
Hyde, K.D., Xu, J., Rapior, S. et al. The amazing potential of fungi: 50 ways we can exploit fungi industrially. Fungal Diversity 97, 1–136 (2019). https://doi.org/10.1007/s13225-019-00430-9
Jacobs A., Van Wyk P.S., Marasas, W.F., Wingfield, B.D., Wingfield, M.J., Coutinho, T.A. Fusarium ananatum sp. nov. in the Gibberella fujikuroi species complex from pineapples with fruit rot in South Africa. Fungal Biol. 2010 Jul;114(7):515–27. doi: 10.1016/j.funbio.2010.03.013.
Labuschagne, R., Venter, E., Boshoff, W. H. P., Pretorius Z. A., Terefe, T., Visser B. (2021). Historical development of the Puccinia triticina population in South Africa. Plant Disease https://doi.org/10.1094/PDIS-10-20-2301-RE
Number of holdings: 63 000 dried specimens
Number of species: ca 13454
Number of types: 2906
