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Research article
Wei-Wei Deng
Anhui Agricultural University
Corresponding Author
Zheng-Zhu Zhang
Anhui Agricultural University
Corresponding Author
ORCiD: https://orcid.org/0000-0003-1564-1428
License:
This work is licensed under a CC BY 4.0 License. Read Full License
Background Caffeine acts as an antifungal agent; however, its underlying inhibition mechanism remains unclear. To investigate variations in caffeine antifungal activity, this study was evaluate the inhibition mechanisms of caffeine on phytopathogens Botryosphaeria dothidea and Colletotrichum gloeosporioides through transcriptomic analysis, which causes leaf necrosis and anthracnose on tea leaves, respectively.
Results Our in vitro results shows that the antifungal activity of caffeine quite different between B. dothidea and C. gloeosporioides. Furthermore, microscopic observation and bioactivity assay results proved that caffeine destroyed the fungal protective layers (cell wall and cell membrane) and subcellular organelles. The transcriptomes of these two fungi exposed to different caffeine concentrations were analyzed by high-throughput sequencing and the results showed that caffeine repressed gene expression involved in the pathways of mRNA surveillance, ribosome biogenesis in eukaryotes, aminoacyl-tRNA biosynthesis, etc. Particularly, caffeine affected gene expression in melanin biosynthesis in C. gloeosporioides, resulting in the disturbances of melanin production and fungal pathogenicity. Manually infected tea leaves showed melanin pigment was important to appressorium development and fungal infection by histopathological observation and fungal biomass quantification. Besides, C. gloeosporioides successfully enters into the host tissue even plant could build multilayer defenses against the fungus, this might be due to the variation in pathogen targets and quantities of secondary metabolites by the host cells.
Conclusions Overall, our findings indicate that caffeine in the environment can reduce the fungal growth and physiological activities. However, the genome-wide expression showed different transcriptional profiles between these fungal isolates. Thus, we believe that target of the caffeine varied among isolates and melanin may play a major role in fungus caffeine tolerance. Further in-depth research required to conclude this hypothesis.
Keywords
Botryosphaeria dothidea, caffeine, Colletotrichum gloeosporioides, anthracnose, melanin, antifungal, tea pathogenic fungi
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This is a preprint, a preliminary version of a manuscript that has not completed peer review at a journal. Research Square does not conduct peer review prior to posting preprints. The posting of a preprint on this server should not be interpreted as an endorsement of its validity or suitability for dissemination as established information or for guiding clinical practice.
Research article
Wei-Wei Deng
Anhui Agricultural University
Corresponding Author
Zheng-Zhu Zhang
Anhui Agricultural University
Corresponding Author
ORCiD: https://orcid.org/0000-0003-1564-1428
Badges
Prescreen
This manuscript passed our Prescreen assessment
Complete author information
Appropriate declaration statements
Potential risks to human health
Prescreen
History
CURRENT STATUS: Posted
Version 1
Posted 13 May, 2020
No community comments so far
Metrics
Comments: 0
PDF Downloads: ...
HTML Views: ...
License:
This work is licensed under a CC BY 4.0 License. Read Full License
Background Caffeine acts as an antifungal agent; however, its underlying inhibition mechanism remains unclear. To investigate variations in caffeine antifungal activity, this study was evaluate the inhibition mechanisms of caffeine on phytopathogens Botryosphaeria dothidea and Colletotrichum gloeosporioides through transcriptomic analysis, which causes leaf necrosis and anthracnose on tea leaves, respectively.
Results Our in vitro results shows that the antifungal activity of caffeine quite different between B. dothidea and C. gloeosporioides. Furthermore, microscopic observation and bioactivity assay results proved that caffeine destroyed the fungal protective layers (cell wall and cell membrane) and subcellular organelles. The transcriptomes of these two fungi exposed to different caffeine concentrations were analyzed by high-throughput sequencing and the results showed that caffeine repressed gene expression involved in the pathways of mRNA surveillance, ribosome biogenesis in eukaryotes, aminoacyl-tRNA biosynthesis, etc. Particularly, caffeine affected gene expression in melanin biosynthesis in C. gloeosporioides, resulting in the disturbances of melanin production and fungal pathogenicity. Manually infected tea leaves showed melanin pigment was important to appressorium development and fungal infection by histopathological observation and fungal biomass quantification. Besides, C. gloeosporioides successfully enters into the host tissue even plant could build multilayer defenses against the fungus, this might be due to the variation in pathogen targets and quantities of secondary metabolites by the host cells.
Conclusions Overall, our findings indicate that caffeine in the environment can reduce the fungal growth and physiological activities. However, the genome-wide expression showed different transcriptional profiles between these fungal isolates. Thus, we believe that target of the caffeine varied among isolates and melanin may play a major role in fungus caffeine tolerance. Further in-depth research required to conclude this hypothesis.
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8
Figure 9
This is a list of supplementary files associated with this preprint. Click to download.
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