Plant & Animal Genome IX Conference

Workshop: Forest Tree Genome Mapping
W26_01.html

GENETIC ANALYSIS OF GROWTH AND WOOD QUALITY TRAITS IN INTERSPECIFIC BACKCROSS FAMILIES OF EUCALYPTUS GRANDIS AND EUCALYPTUS GLOBULUS

¹ Forest Biotechnology Group, Department of Forestry, NC State University, Raleigh, NC 27695

² Shell Forestry Technical Services (SF-RNF), HRI East Malling, West Malling, Kent, ME19 6BJ, UK

We report the preliminary results of a study on the genetic basis of interspecific differences in growth and wood quality traits between two commercially important hardwood tree species, Eucalyptus grandis and E. globulus. This wide interspecific cross was used to obtain two F₂ pseudo-backcross mapping populations. The mapping populations (approximately 350 individuals each) were genotyped for more than 800 AFLP fragments each, using infrared-labeled primers and automated DNA sequencers. This allowed us to construct comparative genetic linkage maps of a superior F₁ hybrid of E. grandis and E. globulus and of the two parental species. A three-way pseudo-testcross approach was used to align all the genetic maps and to accurately track the segregation of E. grandis and E. globulus genetic material in the reciprocal genetic backgrounds. Wood samples were collected from the trees after two years of growth on a field site in Uruguay and used to obtain near-infrared (NIR) spectra for all the surviving backcross family members. The NIR spectra were previously calibrated for several wood properties, including pulp yield, alkali consumption during pulping, lignin content, extractives content, cellulose content, fiber length and fiber coarseness. The calibrations were used to predict wood quality trait values for the backcross family members. The framework linkage maps, wood property data and growth data were used for quantitative trait locus (QTL) analysis in the genomes of E. grandis, E. globulus and the F₁ hybrid. Putative QTLs were detected for several traits using a subset of the backcross individuals.