RESUMO
Rust is one of the most-damaging eucalypt diseases in Brazil and is considered a potential threat to eucalypt plantations worldwide. To determine the mode of inheritance of resistance in the Eucalyptus grandis- Puccinia psidii pathosystem, ten full-sib families, generated from crosses between susceptible and resistant trees, were inoculated with a single-pustule isolate of the pathogen and rust severity was scored. The observed segregation ratios in segregating families suggested major gene control of rust resistance, although clearly incomplete penetrance, variable expressivity and minor genes are also involved in the global rust-resistance response. To identify markers linked to the resistance locus, screening of RAPD polymorphisms was conducted using bulked segregant analysis in a large full-sib family. A linkage group was built around the Ppr1 gene ( P. psidii resistance gene 1) encompassing six RAPD markers, with a genetic window spanning 5 cM with the two most-closely linked flanking markers. Besides these two flanking markers, RAPD marker AT9/917 co-segregated with Ppr1 without a single recombinant in 994 meioses. This tightly linked marker should prove useful for marker-assisted introgression and will provide an initial lead for a positional cloning effort of this resistance allele. This is the first report of a disease resistance gene identified in Eucalyptus, and one of the few examples of the involvement of a major gene in a non-coevolved pathosystem.
Assuntos
Basidiomycota/patogenicidade , Eucalyptus/genética , Eucalyptus/microbiologia , Genes de Plantas/genética , Marcadores Genéticos , Imunidade Inata/genética , Mapeamento Cromossômico , Segregação de Cromossomos , DNA de Plantas/genética , Ligação Genética , Doenças das Plantas/genética , Doenças das Plantas/microbiologia , Reação em Cadeia da Polimerase , Técnica de Amplificação ao Acaso de DNA PolimórficoRESUMO
The Nevoid Basal-Cell Carcinoma Syndrome (NBCC), or as it is also referred to, basal-cell nevus syndrome or Gorlin-Goltz syndrome, is characterized by multiple early-appearing basal cell carcinomas, keratocytosis of the mandible, and anomalies of the ocular, skeletal reproductive system. We describe four patients in the same family, all of them possessing a large number of skin tumors associated with other typical clinical and X-Ray anomalies of NBCC. The definitive treatment of NBCC has yet to be established, however, early diagnosis is very important as well as the periodical follow-up examination of ten patients, mainly due to the transformations in the skin lesions that may occur.