Genetic variability and host specialization among brazilian populations of Ceratocystis fimbriata s.l.

• Autor(a) principal: Fernandes, Fernando Montezano
• Data de Publicação: 2021
• Tipo de documento: Tese
• Idioma: eng
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: https://locus.ufv.br//handle/123456789/30014; https://doi.org/10.47328/ufvbbt.2021.200
• topic: Ceratocystis fimbriata; Mapeamento cromossômico; Eletroforese em gel campo pulsado; Genômica; Variação genética; Fitopatologia

Ceratocystis fimbriata is one of the most important woody plant pathogens worldwide. The fungi colonize the vascular tissue, causing stains on the wood and death of branches or whole plants. Due the wide range of hosts, it is possible that adapted populations of C. fimbriata have been selected to specific hosts and that there is high genetic and physiological variability within the pathogen population. The knowledge of physiological factors that determine host range and host specificity are important aspects for disease management. Therefore, the aims of this study were: (i) determine the specializing for their hosts of 11 isolates on eight hosts; (ii) to investigate the karyotype of isolates of the C. fimbriata species complex from different host plants and geographical origins in Brazil and; (iii) assessed the variability genetic of karyotyped isolates using retrotransposon-microsatellite amplified polymorphism (REMAP). In addition, the identity of the isolates was confirmed conducting multilocus phylogeny using DNA sequences of mating type genes, TEF-1α, and β-tubulin. The analysis based on the C. fimbriata microsatellite (SSR) profiles showed a separation of isolates according to the host. Based on the results of inoculation of 11 isolates on eight hosts, a wide variation in aggressiveness was found. The isolates that were used in this study were more aggressive in their respective hosts. Some hosts, however, were susceptible to isolates from other hosts. Considering the length of xylem lesion caused by C. fimbriata isolates, F. carica was the most susceptible to the isolates tested, followed by M. indica. Only T. cacao and C. guianensis isolates proved to be specialized by their hosts. Polymorphism in chromosome number and size was found, indicating the existence of genomic differences among isolates and occurrence of chromosomal rearrangements in the species complex. The number of chromosomes varied from six to eight and the estimated minimum chromosome sizes were estimated to be between 2.7 to 6.0 Mbp. Small polymorphic chromosomes were observed in all isolates, raising the hypothesis that they could be supernumerary chromosomes. Because chromosomal variation can be caused by transposable elements (TEs), we also assessed the variability of the same isolates using retrotransposon-microsatellite amplified polymorphism (REMAP) molecular marker. REMAP analysis of karyotyped isolates revealed genetic variability and isolates from the same host tend to group in a same cluster.Keywords: Chromosomal rearrangements. Genomic architecture. PFGE. Ceratocystis wilt. Cross-inoculations. Physiological variability.