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| Author(s): |
Sulamita de Freitas Franco
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Campinas, SP. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia |
| Defense date: | 2014-02-28 |
| Examining board members: |
Gonçalo Amarante Guimarães Pereira;
Isabel Rodrigues Gerdhardt;
Jörg Kobarg;
Carlos Augusto Colombo;
Anderson Ferreira da Cunha
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| Advisor: | Gonçalo Amarante Guimarães Pereira; Jorge Mauricio Costa Mondego |
| Abstract | |
The cocoa cultivation have great economic importance in the seed and chocolate producing countries , moving a market that presently reaches around $50 billion. Fungal diseases are the major factor in reducing cocoa production. In Brazil, the main responsible for the production loss is the basidiomycete Moniliophthora perniciosa, known as the etiological agent of witches' broom disease , which devastated the Brazilian production in the 90's disease. The disease is characterized by not eliciting a hypersensitive response (HR), which allows the plant tissue colonization by the fungus. HR is a response that triggers the induction of the expression proteins called PRs (pahtogenesis related), which act against pathogens. Among the PRs, PR5 are known as thaumatins. M. perniciosa genome analysis resulted in the annotation of 13 genes encoding proteins Thaumatin - like (MpTLPs). Despite being well described as antifungal proteins in plants, fungi basidiomycetes studies suggest its involvement in cellular remodeling during mushroom formation. M. perniciosa fungal is the species with the highest number of TLPs described so far, with 6 of them organized in clusters, indicating duplication events. Phylogenetic analysis revealed a greater number of TLPs in basidiomycetes when compared to ascomycetes, indicating their involvement in the formation of mushrooms. Overall, MpTLPs are transcribed during the dry broom disease, where the dead branch is subject to opportunistic fungal infection, indicating the contribution of these proteins in the fight against these fungi, and can be participating in the development of your wallpaper for training basidiocarp and in the cell wall degradation of the plant. Besides MpTLPs, transcriptome analysis revealed a total of 35 MpCSEPs (candidate secreted effectors of pathogenicity protein by the fungus) with RPKM value > 50 have been identified in infected cocoa plants. These genes are preferentially expressed in the early phase of the disease (Green Broom), where we found the fungus still in biotrophic phase. In general, these genes encode small and rich in cysteine that are typical characteristics of virulence effector (AVRs) proteins, which can be evidence that these genes encode potential effectors. After screening, 16 of these genes were chosen for structural characterization. Of these, seven were cloned for expression of heterologous protein, resulting at the end of the study the crystallization of 2 proteins (MpCSEP 5 and 14). The crystals obtained so far been tested in MX1 and MX2 light line, but showed no diffraction and processes of crystals refinement should continue. The proteins obtained in this study may be used in enzymatic assays in future work to its full structural and functional characterization (AU) | |