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Aspergillus flavus (A. flavus) is a ubiquitous and opportunistic fungal pathogen that causes invasive and non-invasive aspergillosis in humans and animals. This fungus is also capable of infecting a large number of agriculture crops (e.g., peanuts, maze, cotton seeds, rice, etc.), causing economic losses and posing serious food-safety concerns when these crops are contaminated with aflatoxins, the most potent naturally occurring carcinogens. In particular, A. flavus and aflatoxins are intensely studied, and they continue to receive considerable attention due to their detrimental effects on humans, animals, and crops. Although several studies have been published focusing on the biosynthesis of the aforementioned secondary metabolites, some of the molecular mechanisms (e.g., posttranslational modifications, transcription factors, transcriptome, proteomics, metabolomics and transcriptome, etc.) involved in the fungal development and aflatoxin biosynthesis in A. flavus are still not fully understood. In this study, a review of the recently published studies on the function of the genes and the molecular mechanisms involved in development of A. flavus and the production of its secondary metabolites is presented. It is hoped that the information provided in this review will help readers to develop effective strategies to reduce A. flavus infection and aflatoxin production.
Elisabeth Tumukunde; Rui Xie; Shihua Wang. Updates on the Functions and Molecular Mechanisms of the Genes Involved in Aspergillus flavus Development and Biosynthesis of Aflatoxins. Journal of Fungi 2021, 7, 666 .
AMA StyleElisabeth Tumukunde, Rui Xie, Shihua Wang. Updates on the Functions and Molecular Mechanisms of the Genes Involved in Aspergillus flavus Development and Biosynthesis of Aflatoxins. Journal of Fungi. 2021; 7 (8):666.
Chicago/Turabian StyleElisabeth Tumukunde; Rui Xie; Shihua Wang. 2021. "Updates on the Functions and Molecular Mechanisms of the Genes Involved in Aspergillus flavus Development and Biosynthesis of Aflatoxins." Journal of Fungi 7, no. 8: 666.
Aspergillus flavus, a ubiquitous filamentous fungus found in soil, plants and other substrates has been reported not only as a pathogen for plants, but also a carcinogen producing fungus for human. Peptidyl-Prolyl Isomerase (PPIases) plays an important role in cell process such as protein secretion cell cycle control and RNA processing. However, the function of PPIase has not yet been identified in A. flavus. In this study, the PPIases gene from A. flavus named ppci1 was cloned into expression vector and the protein was expressed in prokaryotic expression system. Activity of recombinant ppci1 protein was particularly inhibited by FK506, CsA and rapamycin. 3D-Homology model of ppci1 has been constructed with the template, based on 59.7% amino acid similarity. The homologous recombination method was used to construct the single ppci1 gene deletion strain Δppci1. We found that, the ppci1 gene plays important roles in A. flavus growth, conidiation, and sclerotia formation, all of which showed reduction in Δppci1 and increased in conidiation compared with the wild-type and complementary strains in A. flavus. Furthermore, aflatoxin and peanut seeds infection assays indicated that ppci1 contributes to virulence of A. flavus. Furthermore, we evaluated the effect of PPIase inhibitors on A. flavus growth, whereby these were used to treat wild-type strains. We found that the growths were inhibited under every inhibitor. All, these results may provide valuable information for designing inhibitors in the controlling infections of A. flavus.
Saleem Ahmad; Sen Wang; Weizhong Wu; Kunlong Yang; Yan Feng Zhang; Elisabeth Tumukunde; Shihua Wang; Yu Wang. Functional Analysis of Peptidyl-prolyl cis-trans Isomerase from Aspergillus flavus. International Journal of Molecular Sciences 2019, 20, 2206 .
AMA StyleSaleem Ahmad, Sen Wang, Weizhong Wu, Kunlong Yang, Yan Feng Zhang, Elisabeth Tumukunde, Shihua Wang, Yu Wang. Functional Analysis of Peptidyl-prolyl cis-trans Isomerase from Aspergillus flavus. International Journal of Molecular Sciences. 2019; 20 (9):2206.
Chicago/Turabian StyleSaleem Ahmad; Sen Wang; Weizhong Wu; Kunlong Yang; Yan Feng Zhang; Elisabeth Tumukunde; Shihua Wang; Yu Wang. 2019. "Functional Analysis of Peptidyl-prolyl cis-trans Isomerase from Aspergillus flavus." International Journal of Molecular Sciences 20, no. 9: 2206.
Woronin bodies are fungal-specific organelles whose formation is derived from peroxisomes. The former are believed to be involved in the regulation of mycotoxins biosynthesis, but not in their damage repair function. The hexagonal peroxisome protein (HexA or Hex1) encoded by hexA gene in Aspergillus is the main and the essential component of the Woronin body. However, little is known about HexA in Aspergillus flavus. In this study, hexA knock-out mutant (ΔhexA) and complementation strain (ΔhexAC) were produced using homologous recombination. The results showed that, ΔhexA and ΔhexAC were successfully constructed. And the data analysis indicated that the colony diameter, stress sensitivity and the sclerotia formation of A. flavus were nearly not affected by the absence of HexA. Yet, the deletion of hexA gene reduced the production of asexual spores and lessened virulence on peanuts and maize seeds markedly. In addition, it was also found that there was a significant decrease of Aflatoxin B1 production in deletion mutant, when compared to wild type. Therefore, it suggested that the hexA gene has an essential function in conidia production and secondary metabolism in A. flavus. The gene is also believed to be playing an important role in the invasion of A. flavus to the host.
Jun Yuan; Ding Li; Ling Qin; Jiaojiao Shen; Xiaodong Guo; Elisabeth Tumukunde; Mingzhu Li; Shihua Wang. HexA is required for growth, aflatoxin biosynthesis and virulence in Aspergillus flavus. BMC Molecular Biology 2019, 20, 1 -13.
AMA StyleJun Yuan, Ding Li, Ling Qin, Jiaojiao Shen, Xiaodong Guo, Elisabeth Tumukunde, Mingzhu Li, Shihua Wang. HexA is required for growth, aflatoxin biosynthesis and virulence in Aspergillus flavus. BMC Molecular Biology. 2019; 20 (1):1-13.
Chicago/Turabian StyleJun Yuan; Ding Li; Ling Qin; Jiaojiao Shen; Xiaodong Guo; Elisabeth Tumukunde; Mingzhu Li; Shihua Wang. 2019. "HexA is required for growth, aflatoxin biosynthesis and virulence in Aspergillus flavus." BMC Molecular Biology 20, no. 1: 1-13.
Aspergillus flavus is one of the fungi from the big family of Aspergillus genus and it is capable of colonizing a large number of seed/crops and living organisms such as animals and human beings. SakA (also called hogA/hog1) is an integral part of the mitogen activated protein kinase signal of the high osmolarity glycerol pathway. In this study, the AfsakA gene was deleted (∆AfsakA) then complemented (∆AfsakA::AfsakA) using homologous recombination and the osmotic stress was induced by 1.2 mol/L D-sorbital and 1.2 mol/L sodium chloride. The result showed that ∆AfsakA mutant caused a significant influence on conidial formation compared to wild-type and ∆AfsakA::AfsakA strains. It was also found that AfsakA responds to both the osmotic stress and the cell wall stress. In the absence of osmotic stress, ∆AfsakA mutant produced more sclerotia in contrast to other strains, whereas all strains failed to generate sclerotia under osmotic stress. Furthermore, the deletion of AfsakA resulted in the increase of Aflatoxin B1 production compared to other strains. The virulence assay on both maize kernel and peanut seeds showed that ∆AfsakA strain drastically produced more conidia and Aflatoxin B1 than wild-type and complementary strains. AfSakA-mCherry was located to the cytoplasm in the absence of osmotic stress, while it translocated to the nucleus upon exposure to the osmotic stimuli. This study provides new insights on the development and evaluation of aflatoxin biosynthesis and also provides better understanding on how to prevent Aspergillus infections which would be considered the first step towards the prevention of the seeds damages caused by A. flavus.
Elisabeth Tumukunde; Ding Li; Ling Qin; Yu Li; Jiaojiao Shen; Shihua Wang; Jun Yuan. Osmotic-Adaptation Response of sakA/hogA Gene to Aflatoxin Biosynthesis, Morphology Development and Pathogenicity in Aspergillus flavus. Toxins 2019, 11, 41 .
AMA StyleElisabeth Tumukunde, Ding Li, Ling Qin, Yu Li, Jiaojiao Shen, Shihua Wang, Jun Yuan. Osmotic-Adaptation Response of sakA/hogA Gene to Aflatoxin Biosynthesis, Morphology Development and Pathogenicity in Aspergillus flavus. Toxins. 2019; 11 (1):41.
Chicago/Turabian StyleElisabeth Tumukunde; Ding Li; Ling Qin; Yu Li; Jiaojiao Shen; Shihua Wang; Jun Yuan. 2019. "Osmotic-Adaptation Response of sakA/hogA Gene to Aflatoxin Biosynthesis, Morphology Development and Pathogenicity in Aspergillus flavus." Toxins 11, no. 1: 41.