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| Author(s): |
Guilherme Thomaz Pereira Brancini
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Ribeirão Preto. |
| Institution: | Universidade de São Paulo (USP). Faculdade de Ciências Farmacêuticas de Ribeirão Preto (PCARP/BC) |
| Defense date: | 2019-10-17 |
| Examining board members: |
Gilberto Ubida Leite Braga;
Maria Celia Bertolini;
Italo Delalibera Junior;
Iran Malavazi;
Sergio Akira Uyemura
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| Advisor: | Gilberto Ubida Leite Braga |
| Abstract | |
Metarhizium acridum is an important entomopathogenic fungus currently used for the biological control of insect pests. The success of biological control is heavily dependent on the fungus ability to tolerate environmental stressors such as heat and ultraviolet radiation. One of such stressor is solar ultraviolet-B radiation (UV-B, 280-315 nm), which is capable of delaying conidia germination and even inactivate the fungus, thus reducing insect control efficiency. It was previously shown that growing Metarhizium in the presence of visible light induces the fungus to produce conidia with increased tolerance to UV-B radiation. Visible light is an important stimulus for many fungi as it regulates a wide variety of biological processes and serves additionally as a signal for space and time. Responses to light in fungi vary according to light quality and can be divided in responses to blue, green, and red light. In the present thesis, three major questions are addressed: (1) what radiation color (blue or red) is responsible for the increased tolerance to UV-B radiation after light exposure? (2) How does light exposure increase tolerance to UV-B radiation? (3) How does light globally regulate gene expression both transcriptionally and post-transcriptionally? Here it is shown that blue light, and not red light, increases tolerance to UV-B radiation. Also, light induces the expression of a photolyase-coding gene and it was observed that photoreactivation, and not dark repair, is the major component behind UV-B radiation tolerance. Transcriptomics via mRNA-Sequencing revealed that light regulates the transcription of approximately 11% of the genome. However, quantitative proteomics showed that light changed the abundance of only 57 proteins, thus showing that few changes at the mRNA level were translated to the protein level. Proteomics also revealed that light exposure caused a reduction in the abundance of translation-related proteins such as subunits of the eukaryotic translation initiation factor 3 and ribosomal proteins. This reduction in translational activity is consistent with a model in which light is both a signal and a stress to the cell. Furthermore, decreased translational activity is a potential explanation for the reduced number of light-regulated proteins. Finally, the results presented here highlight the importance of measuring protein levels in order to fully understand light responses in fungi (AU) | |
| FAPESP's process: | 15/24305-0 - Evaluating the effects of blue and red light on the stress tolerance and the proteome of the entomopathogenic fungus Metarhizium acridum |
| Grantee: | Guilherme Thomaz Pereira Brancini |
| Support Opportunities: | Scholarships in Brazil - Doctorate |