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Genetic Variation and Variation in Aggressiveness to Native and Exotic Hosts Among Brazilian Populations of Ceratocystis fimbriata

May 2011 , Volume 101 , Number  5
Pages  555 - 566

Thomas C. Harrington, Daniel J. Thorpe, and Acelino C. Alfenas

First and second authors: Department of Plant Pathology, Iowa State University, Ames 50011; and third author: Departmento de Fitopatologia, Universidade Federal de Viçosa, Minas Gerais, Brazil.

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Accepted for publication 21 December 2010.

Ceratocystis fimbriata is a complex of many species that cause wilt and cankers on woody plants and rot of storage roots or corms of many economically important crops worldwide. In Brazil, C. fimbriata infects different cultivated crop plants that are not native to Brazil, including Gmelina arborea, Eucalyptus spp., Mangifera indica (mango), Ficus carica (fig), and Colocasia esculenta (inhame). Phylogenetic analyses and inoculation studies were performed to test the hypothesis that there are host-specialized lineages of C. fimbriata in Brazil. The internal transcribed spacer region ribosomal DNA sequences varied greatly but there was little resolution of lineages based on these sequences. A portion of the MAT1-2 mating type gene showed less variation, and this variation corresponded more closely with host of origin. However, mango isolates were found scattered throughout the tree. Inoculation experiments on the five exotic hosts showed substantial variation in aggressiveness within and among pathogen populations. Native hosts from the same families as the exotic hosts tended to be less susceptible than the cultivated hosts, but there was little correlation between aggressiveness to the cultivated and native hosts of the same family. Cultivation and vegetative propagation of exotic crops may select for strains that are particularly aggressive on those crops.

Additional keywords: C. cacaofunesta, C. manginecans, C. platani, host specialization.

© 2011 The American Phytopathological Society