Mapeamento de QTL para características de interesse industrial da madeira de Eucalyptus em progênie de híbridos interespecíficos
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2009-02-26
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Universidade Federal de Goiás
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In this work a genetic map and QTL mapping were built for growth and wood quality characters in a interspecific hybrids progeny of Eucalyptus. Samples of genomic DNA were isolated from 200 individuals belonging to a interspecific hybrids progeny. A screening of 300 pairs microsatellite loci (SSR) primers was done and from those 76 loci were selected to compose 19 tetraplex combinations, based in presence of valid polimorfism for QTL mapping and in quality of allele’s amplification. Among the 76 loci appraised in multiplex system, 14 presented significant distortion of segregation in χ2 test using "Criterion of Bonferroni" with 5% of significance, and they were excluded of mapping analyses. Using LOD 3 and recombination fraction of 0.40, 12 linkage groups compatible with described in other mapping works in Eucalyptus were identified. An integrated genetic map was obtained with total length of 1240 cM and medium distance among marks of 22 cM, It provides a covering genomic of approximately 75% in relation to genome size of Eucalyptus gender. A part of density appraised by pilodyn apparatus, all others characters showed QTL association through variance analysis (single marks analysis). For growth characters, four loci were associated to seven QTL and 19% for genotypic variation of diameter, 18% for height and 10% for volume these QTL were capable to explain. Among wood quality characters evaluated by NIRS, three QTL were capable to explain 17% of genotypic variance for density, while for yield cellulose, four QTL together were capable to explain 7,5% of this variance. For the characters related with lignin properties also evaluated by NIRS, were identified three QTL capable to explain 9% of genotypic variation for lignin quantity, and two QTL were capable to explain 6% of genotypic variation for siringil/guaiacil relationship. Most of identified QTL for different characters appraised in this work coincided with linkage groups and as well the amount of
variance of QTL detected by other authors, which carried out QTL mapping for these same characters. Although comparatively the SAM showed inferior efficiency in relation to fenotypic selection, it can be useful for optimization of futures field experiments into progenies which QTL mapping already was accomplished, where only best genotypes can be stablished in field instead to whole progeny. The application of SAM in forest breeding programs is possible to be used in early selection starting from second breeding generation, using QTL information of crosses mapped in these breeding programs. However, QTL used for SAM should be robust in progenies where they were mapped, like as QTL identified in linkage group 9 for character DAP in this dissertation, that beside consistence datas in progeny DG x GL2, were capable to explain the same amount of variability for QTL mapped by Kirst et al. (2007) (12%), which used different genetic markers and techniques for QTL mapping. These results prove that application of SAM is viable in breeding programs, and apart of peculiarities in each crossing, certain linkage groups are stable among different progenies for a same character.
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MEDINA-MACEDO, L. Mapeamento de QTL para características de interesse industrial da madeira de Eucalyptus em progênie de híbridos interespecíficos. 2009. 143 f. Dissertação (Mestrado em Agronomia) - Universidade Federal de Goiás, Goiânia, 2009.