Genomic changes in the infectious yeast Candida tropicalis may play a role in its resistance to antifungals, according to a study published on April 1st in the open-access journal, PLOS Biology by Guanghua Huang at Fudan University, China, and colleagues. These genomic changes can be brought on by a common antifungal, TBZ. The study demonstrates that the use of TBZ in agriculture may contribute to the increasing problem of antifungal resistance.
C. tropicalis is one of the most common fungi to infect humans, and while many infections are treatable, some can be life-threatening, especially among people who are immunocompromised. Infections of C. tropicalis and other fungi are of growing concern as many of these pathogens are becoming increasingly resistant to antifungal medicines. However, the biological mechanisms underlying this resistance are not well understood.
The researchers surmised that these yeast may be developing resistance from exposure to antifungal agents and one of the most common uses of these agents is in agriculture. When C. tropicalis was exposed to the agricultural fungicide TBZ, the researchers found that the yeast cells' genomes became unstable, losing half their DNA.
It was previously thought that C. tropicalis requires two copies of each chromosome to survive, known as being diploid. However, these cells with one copy of each chromosome — or haploid cells — persisted and were resistant to TBZ and similar antifungals used in medicine.
How exactly this change in chromosomes creates antifungal-resistance is a question that remains to be answered. This study, however, provides evidence that the use of antifungals in agriculture is likely a key factor in the increasing levels of resistance seen among C. tropicalis and perhaps even other infectious yeast, such as the recently emerged "superbug" fungal pathogen Candida auris.
The authors add, "The human fungal pathogen Candida tropicalis is widely distributed in natural environments and often exposed to agricultural fungicides. This study reports that tebuconazole, a triazole fungicide, can induce the formation of haploid cells (having a one set of chromosomes) and promote genetic diversity in this fungus, which has long been thought to be an "obligate" diploid organism (having two sets of chromosomes)."
In your coverage, please use this URL to provide access to the freely available paper in PLOS Biology: https://plos.io/4cdGJoE
Citation: Hu T, Zheng Q, Cao C, Li S, Huang Y, Guan Z, et al. (2025) An agricultural triazole induces genomic instability and haploid cell formation in the human fungal pathogen Candida tropicalis. PLoS Biol 23(4): e3003062. https://doi.org/10.1371/journal.pbio.3003062
Author countries: China, United States
Funding: This work was supported by the National Key Research and Development Program of China (grants 2022YFC2303000 to JB and HD; 2021YFC2300400 to GH), the National Natural Science Foundation of China (grants 31930005 and 82272359 to GH, 32000018 and 32170193 to JB, 82172290 and 82002123 to HD, 82402648 to TH), the National Institutes of Health (NIH) National Institute of General Medical Sciences (NIGMS) (grant R35GM124594 to CJN), and by the Kamangar family in the form of an endowed chair (to CJN). The content is the sole responsibility of the authors and does not represent the views of the funders. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.
