Genetic variability of Ceratocystis fimbriata on Tectona grandis and Carapa guianensis in Brazil

• Ano de defesa: 2016
• Autor(a) principal: Valdetaro, Denise Cristina de Oliveira Franco
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Viçosa
• Palavras-chave em Português: Teca (Árvore); Tectona grandis; Andiroba; Carapa guianensis; Fungos; Ceratocystis fimbriata; Diversidade genética; Fitopatologia
• Link de acesso: http://www.locus.ufv.br/handle/123456789/10806

Recently, Ceratocystis fimbriata Ellis & Halsted was reported in Tectona grandis L. f (teak) and Carapa guianensis Aubl. (andiroba) in Brazil. In teak, the fungus causes death and wood discoloration, which affects the production of high valuable timber. In andiroba, the fungus infects and kills seeds and seedlings, which may affect negatively its natural regeneration and, probably, its biodiversity. The identification of C. fimbriata on these hosts was based only on morphological characteristics and analysis of ITS rDNA sequences. Furthermore, the genetic and physiological variability of C. fimbriata populations as well as their phylogenetic relationships with other isolates and species of Ceratocystis were not analyzed . Such studies are essential to support disease management strategies. Therefore, this study aimed to: 1) Assess the relationship among isolates of the fungus from both host species with isolates from other hosts of the Latin American Clade (LAC) by using mating type genes and ITS rDNA region. 2) Assess the interesterility through crossings between isolates from different host species. 3) Determine the genetic variability in populations of C. fimbriata through microsatellite markers and their physiological especialization by f cross-inoculation experiments. Out of 24 isolates of the fungus obtained from teak from of locations in the state of Mato Grosso, and of 73 isolates of C. fimbriata from andiroba in the states of Acre, Roraima and Amazonas, new ITS haplotypes and mating types identified were distributed among other isolates within the LAC and reside in a single group that includes isolates from sweet potato, from which the species was originally described. Teak and andiroba isolates were inter fertile with other strains of C. fimbriata, showing that this is a single biological species of C. fimbriata. Microsatellite analysis of the fungal population on teak showed low genetic variability. In cross-inoculations, although teak plants presented relatively small lesions, two isolates differed from the control. The eucalyptus isolates were not pathogenic on teak. The populations of C. fimbriata from andiroba of the three states (AC, AM, and RR) showed 14 genotypes and intermediary levels of genetic variability compared to other native populations of the fungus in Brazil. Cross-inoculations of andiroba, teak, eucalyptus and mango isolates suggest that the isolates of C. fimbriata from these species are host specific and that there is variability in aggressiveness among isolates of the fungus from andiroba.