Mapeamento de gene letal, responsável pela distorção de segregação e detecção de QTL para resistência à ferrugem (Puccinia psidii) em Eucalyptus spp

• Autor(a) principal: Rosado, Tatiana Barbosa
• Data de Publicação: 2007
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1270
• topic: Eucalyptus; Puccinia psidii; Mapeamento genético; Eucalyptus; Puccinia psidii; Genetic mapping; CNPQ::CIENCIAS BIOLOGICAS::GENETICA::GENETICA QUANTITATIVA

The rust caused by Puccinia psidii is a limited factor to the Eucalyptus production. In this way, inheritance studies for rust, subsidized by mapping analysis and detection of QTL (s) becomes important to aid the breeding programs. However, in Eucalyptus, mainly in interspecific crossings, a high frequency of loci with segregation distortion (SD) is observed. The SD hinders to predict the genotipic segregation and to estimate the recombination frequencies in genomic analysis. Genetic maps that neglect the segregation distortion provide a bias estimation of the distance among markers. This way, this work aimed to select a interspecific cross to identify the cause of segregation distortion of microsatellite loci, in the linkage group three; to develop a methodology to map those loci and to detect QTLs responsible for the rust resistance. Functions were presented to estimate the amount of distortion of the loci of the linkage group three that exhibited segregation distortion. From the amount of distortion an estimator was established to map those loci. It was presupposed and confirmed that the segregation distortion was due to a lethal gene that acts in the gamete formation. Starting from the amount of distortion and from the estimated recombination frequency for each locus, they were mapped in relation to the lethal loci. Phenotypic data related to the rust and genotypic information of seven microsatellite of the linkage group three (EMBRA 227, EMBRA 189, EMBRA 122, EMBRA 171, EMBRA 125, EMBRA 239, EMBRA 181) were used for the QTLs detection. The QTL detection, responsible for the rust resistance, was made through methodologies based in simple mark and simple interval mapping. The methodologies of simple marks evidenced statistical significance for the markers EMBRA 181 and EMBRA 125, and the last one showed the largest statistical significance. For the simple interval mapping method, QTL was mapped 0,002 cM from EMBRA 125. Mapped QTL explained 42% of the phenotypic variation. Once the QTL was mapped very close to the locus marker EMBRA 125 and it explains great proportion of the phenotypic variance, it is interesting to use in markers assisted selection and eventual positional cloning of the rust resistance gene.