Genomic and transcriptomic analyses of Austropuccinia psidii and Ceratocystis fimbriata, the causal agents of myrtle rust and ceratocystis wilt, respectively

• Ano de defesa: 2020
• Autor(a) principal: Santos, Samuel Alves dos
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Viçosa; Fitopatologia
• Palavras-chave em Português: Plantas - Resistência a doenças e pragas; Análise do genoma; Expressão gênica; Fitopatologia
• Link de acesso: https://locus.ufv.br//handle/123456789/30120

Austropuccinia psidii and Ceratocystis fimbriata complex, the causal agents of Myrtle rust and Ceratocystis wilt, respectively, have been considered important fungal pathogens especially due to their wide and expanding host range across the world. Whole genome sequencing and RNA- Seq are powerful tools that provide information about pathogens biology, plasticity, evolution, and pathogenicity, which are crucial to a better understanding of host-pathogen interactions. Therefore, in chapter 1 of this Thesis, we present a high-quality assembly and annotation of the haploid nuclear genome and de novo transcriptome of A. psidii epitype guava (Psidium guajava) isolate, which is so far the largest genome among Pucciniales rust fungi. Additionally, in chapter 2, we evaluated the gene expression profile of two contrasting Eucalyptus grandis genotypes in resistance level to rust (A. psidii) and found a constitutive overexpression of several resistance-related genes in the resistant genotype compared to the susceptible one. In chapter 3, we present de novo genome assembly and annotation for the nuclear genome of 21 fungal pathogens of the C. fimbriata complex from different host species and geographic region. Comparative genomic analysis revealed that independently on host and geographic location, the majority of genome features showed a high level of similarity among all Ceratocystis isolates. Moreover, in order to understand the molecular mechanisms related to C. fimbriata pathogenicity on Eucalyptus spp., in chapter 4, we evaluated the first transcriptome of C. fimbriata LPF1912 isolate during its infection on 16 eucalyptus genotypes. Through comparative genomic analysis with C. eucalypticola and Calonectria pseudoreteaudii, which also infect eucalyptus, we identified different pathogenicity-related genes among the three eucalyptus pathogens. Finally, our genomic and transcriptomic dataset analyses provide a valuable framework for future studies leading to a better comprehension of the biology, plasticity, evolution, and pathogenicity of A. psidii and C. fimbriata complex. Keywords: Puccinia psidii. Comparative genomic analysis. Differentially expressed genes. RNA-Seq. OrthoMCL analysis. Plant resistance.