Prelecionista: Rosiane F. Almeida
Orientador: Acelino Couto Alfenas
Data: 19/11/24, às 16h
Local: Anfiteatro do ESB

Resumo: Eucalyptus globulus can produce high-density wood with high cellulose and low lignin content. However, plantations can be affected by eucalypt rust, caused by Austropuccinia psidii and/or Teratosphaeria Leaf Disease (TLD), caused by Teratosphaeria nubilosa. Planting resistant materials is the most efficient strategy to control both diseases. Successful control requires the availability of resistance sources, a comprehensive understanding of pathogen population diversity, and the selection of resistant host genotypes through inoculations under controlled environmental conditions. This study aimed to assess the resistance of native families of E. globulus to A. psidii and T. nubilosa (Brazilian populations) compared to the pathogen populations in Australia. Additionally, it aimed to elucidate the sexual cycle of A. psidii in Eucalyptus and its potential role in the genetic diversity observed among populations. The results of A. psidii inoculations showed that families of the subrace Southern Tasmania exhibited broad-spectrum resistance to both rust biotypes: the Brazilian biotype infecting Eucalyptus spp. and Syzygium jambos, and the pandemic biotype that occurs in Australia. However, the Brazilian biotype appears to be more virulent. Although physiological differences between the two biotypes of A. psidii were confirmed, sexual reproduction could not be conclusively identified as the source of the genotypic variation observed between these populations through inoculation tests with basidiospores of A. psidii race 1 (biotype Brazilian) in Eucalyptus. A single multilocus genotype (MLG) of T. nubilosa predominates in Brazil and Spain – an important E. globulus-producing country. However, this MLG differs from a representative isolate from Australia. Although this, the results of T. nubilosa inoculations under controlled environmental conditions carried out in Brazil were consistent with field trial outcomes in Australia using the same E. globulus families. The most TLD-resistant populations of E. globulus are native to Northern Tasmania, regions of the Bass Strait, and extend northward into mainland Australia. These families can be targeted in genetic breeding programs, with selected plants being cloned and cultivated in countries such as Spain.