Plant Genome IV Conference Plant Genome IV Conference
We are evaluating opportunities to incorporate genomic analysis in Eucalyptus breeding and clonal plantation programs. We are investigating the patterns of QTL stability across ages, environments and genetic backgrounds for height growth. Preliminary results for QTL x Age indicate stability of QTL expression within the first 6 months. Significant QTL x Environment interaction was detected in contrasting environments involving mainly the expression of specific QTLs in each environment. QTLs with higher LOD scores and larger effects were more stable across environments. To investigate QTL x genetic background interaction we are using a number of full-sib families that were generated from a common maternal parent. A survey of a set of 4 QTL alleles previously mapped for the common parent indicates significant QTL x background interaction despite the fact that these alleles were originally detected in a representative half-sib background. Genomic relatedness data among elite breeding clones has been used to define key divergent crosses to optimize new maps construction and will be used to maximize divergence between contiguous clonal field blocks. Comparative mapping indicates that a large proportion of RAPD loci are transferable among tree maps and that greater meiotic recombination occurs in female gametes of Eucalyptus. Synteny among tree maps will allow a directed search for new QTL alleles. Furthermore as the success in selecting for a particular QTL allele depends on the recombination frequency with the bracketing markers, a greater probability of success is expected when the QTL targeted is contributed by the male parent.