Publications by authors named "Z Wilhelm De Beer"

144 Publications

Fire impacts bacterial composition in Protea repens (Proteaceae) infructescences.

FEMS Microbiol Lett 2021 Oct 9. Epub 2021 Oct 9.

Department of Biochemistry, Genetics and Microbiology, Forestry and Agriculture Biotechnology Institute, University of Pretoria, Pretoria, South Africa.

The diverse bacterial communities in and around plants provide important benefits, such as protection against pathogens and cycling of essential minerals through decomposition of moribund plant biomass. Biodiverse fynbos landscapes generally have limited dead-wood habitats due to the absence of large trees and frequent fire. In this study, we determined the effect of a fire disturbance on the bacterial communities in a fynbos landscape dominated by the shrub Protea repens using 16S rRNA amplicon sequencing. The bacterial community composition in newly formed fruiting structures (infructescences) and soil at a recently burnt site was different to that in an unburnt site. Bacteria inhabiting P. repens infructescences were similar to well-known taxa from decomposing wood and litter. This suggests a putative role for these above-ground plant structures as reservoirs for post fire decomposer bacteria. The results imply that inordinately frequent fires, which are commonplace in the Anthropocene, are a significant disturbance to bacterial communities and could affect the diversity of potentially important microbes from these landscapes.
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http://dx.doi.org/10.1093/femsle/fnab132DOI Listing
October 2021

Phylogenetic and phylogenomic analyses reveal two new genera and three new species of ophiostomatalean fungi from termite fungus combs.

Mycologia 2021 Sep 3:1-19. Epub 2021 Sep 3.

Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute, University of Pretoria, Private Bag X20, Pretoria, 0028 South Africa.

The Ophiostomatales (Ascomycota) accommodates more than 300 species characterized by similar morphological adaptations to arthropod dispersal. Most species in this order are wood-inhabiting fungi associated with bark or ambrosia beetles. However, a smaller group of species occur in other niches such as in soil and infructescences. Recent surveys of fungus gardens (fungus combs) of fungus-growing termites led to the discovery of characteristic ophiostomatalean-like fruiting structures. In this study, these ophiostomatalean-like fungi were identified using morphological characteristics, conventional molecular markers, and whole genome sequencing. In addition, the influence of the extracts derived from various parts of combs on the growth of these fungi in culture was considered. Based on phylogenomic analyses, two new genera ( and ) were introduced to accommodate these ophiostomatalean species. Phylogenetic analyses revealed that the isolates resided in three well-supported lineages, and these were described as three new species (, and ). Culture-based studies showed that these species do not depend on the comb material for growth.
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http://dx.doi.org/10.1080/00275514.2021.1950455DOI Listing
September 2021

Fungal associates of an invasive pine-infesting bark beetle, , including seven new Ophiostomatalean fungi.

Persoonia 2020 Dec 22;45:177-195. Epub 2020 Jul 22.

Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Private Bag X20, Pretoria 0028, South Africa.

The red turpentine beetle (RTB; ) is a bark beetle that is native to Central and North America. This insect is well-known to live in association with a large number of Ophiostomatalean fungi. The beetle is considered a minor pest in its native range, but has killed millions of indigenous pine trees in China after its appearance in that country in the late 1990s. In order to increase the base of knowledge regarding the RTB and its symbionts, surveys of the beetle's fungal associates were initially undertaken in China, and in a subsequent study in its native range in North America. A total of 30 Ophiostomatalean species that included several undescribed taxa, were identified in these surveys. In the present study, seven of the undescribed taxa collected during the surveys were further characterised based on their morphological characteristics and multi-gene phylogenies. We proceeded to describe five of these as novel spp. and two as new species of . Four of the spp. resided in the species complex, while one formed part of the -species complex One sp. was a member of the -species complex, while the only new species from China was closely related to . Two of the previously undescribed taxa from North America were shown to be congeneric with , implying that this species was most often isolated in association with the RTB in North America. The undescribed taxon from North America was identified as , and like , this species was also not recognized during the initial North American survey. Resolving the identities of these taxa provides essential baseline information to better understand the movement of fungal pathogens with this beetle. This then enhances our ability to accurately assess and predict the risks of invasions by these and related fungi.
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http://dx.doi.org/10.3767/persoonia.2020.45.07DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8375344PMC
December 2020

Ancestral predisposition toward a domesticated lifestyle in the termite-cultivated fungus Termitomyces.

Curr Biol 2021 Oct 16;31(19):4413-4421.e5. Epub 2021 Aug 16.

Laboratory of Genetics, Wageningen University & Research, Droevendaalsesteeg 1, 6708PB Wageningen, the Netherlands. Electronic address:

The ancestor of termites relied on gut symbionts for degradation of plant material, an association that persists in all termite families. However, the single-lineage Macrotermitinae has additionally acquired a fungal symbiont that complements digestion of food outside the termite gut. Phylogenetic analysis has shown that fungi grown by these termites form a clade-the genus Termitomyces-but the events leading toward domestication remain unclear. To address this, we reconstructed the lifestyle of the common ancestor of Termitomyces using a combination of ecological data with a phylogenomic analysis of 21 related non-domesticated species and 25 species of Termitomyces. We show that the closely related genera Blastosporella and Arthromyces also contain insect-associated species. Furthermore, the genus Arthromyces produces asexual spores on the mycelium, which may facilitate insect dispersal when growing on aggregated subterranean fecal pellets of a plant-feeding insect. The sister-group relationship between Arthromyces and Termitomyces implies that insect association and asexual sporulation, present in both genera, preceded the domestication of Termitomyces and did not follow domestication as has been proposed previously. Specialization of the common ancestor of these two genera on an insect-fecal substrate is further supported by similar carbohydrate-degrading profiles between Arthromyces and Termitomyces. We describe a set of traits that may have predisposed the ancestor of Termitomyces toward domestication, with each trait found scattered in related taxa outside of the termite-domesticated clade. This pattern indicates that the origin of the termite-fungus symbiosis may not have required large-scale changes of the fungal partner.
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http://dx.doi.org/10.1016/j.cub.2021.07.070DOI Listing
October 2021

Asthma in Youth and Early-Onset Type 2 Diabetes: A Nationwide Study of 1.72 Million Israeli Adolescents.

J Clin Endocrinol Metab 2021 Jul 22. Epub 2021 Jul 22.

Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.

Background: The prevalence of both asthma and early onset diabetes is on the rise, however the association between them remains unclear. We examined a possible association of asthma at adolescence with type 2 diabetes in young adulthood.

Methods: This is a nationwide, population-based study of 1,718,541 Israeli adolescents (59% males; mean age 17.3 years; range 16-19 years), examined before compulsory military service during 1992-2016, with data linked to the Israeli National Diabetes Registry. Asthma diagnosis and severity were determined by a board-certified pulmonologist and based on spirometry tests.

Results: Type 2 diabetes developed in 58/9,090 (0.64%), 507/97,059 (0.52%), 114/23,332 (0.49%), and 7,095/1,589,060 (0.44%) persons with moderate-to-severe, mild, inactive, and no history of asthma, respectively, during a mean follow-up >13 years. The respective odds ratios (ORs) were 1.33 (95%CI, 1.02-1.74), 1.17 (1.06-1.28), and 1.09 (0.9-1.31), considering those without asthma history as the reference, in a model adjusted for birth year, sex, BMI, and other socio-demographic variables. The association persisted when the analysis accounted for coexisting morbidities, and when persons without asthma, individually matched by age, sex, birth year, and BMI were the reference. Both mild and moderate-to-severe asthma were associated with type 2 diabetes before age 35 years: ORs 1.18 (1.05-1.34) and 1.44 (1.05-2.00), respectively. The strength of the association was accentuated over time. The effect was unchanged when adjusted for oral and inhaled glucocorticoid use.

Conclusion: Adolescents with active asthma have higher risk to develop type 2 diabetes. This seems related to disease severity, independent of adolescent obesity status, apparent before age 35 years, and more pronounced in recent years.
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http://dx.doi.org/10.1210/clinem/dgab542DOI Listing
July 2021
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