Search

Genomic studies have been used to identify genes underlying many important plant secondary metabolic pathways. However, genes for salicinoid phenolic glycosides (SPGs)—ecologically important compounds with significant commercial, cultural, and medicinal applications—remain largely undescribed. We used a linkage map derived from a full‐sib population of hybrid cottonwoods (Populus spp.) to search for quantitative trait loci (QTL) for the SPGs salicortin and HCH‐salicortin. SSR markers and primer sequences were used to anchor the map to the V3.0 P. trichocarpa genome. We discovered 21 QTL for the two traits, including a major QTL for HCH‐salicortin (R2 = .52) that colocated with a QTL for salicortin on chr12. Using the V3.0 Populus genome sequence, we identified 2,983 annotated genes and 1,480 genes of unknown function within our QTL intervals. We note ten candidate genes of interest, including a BAHD‐type acyltransferase that has been potentially linked to PopulusSPGs. Our results complement other recent studies in Populus with implications for gene discovery and the evolution of defensive chemistry in a model genus. To our knowledge, this is the first study to use a full‐sib mapping population to identify QTL intervals and gene lists associated with SPGs.

Teak tree (Tectona grandis L.f.) is a tropical tree specie naturally distributed in Southeast Asia, where it is also widely planted. It is planted as exotic specie in Africa, South and Central America. Tree improvement activities have been initiated in several countries including Costa Rica, which it has become the largest teak developer in Latin America. Teak sprouts were collected in a 4-yearold progeny test from the best two and the worst two families for volume as well as for stem quality traits. A DNA extraction protocol described before was modified in order to yield high quality DNA.AFLP reactions were performed as described previously. Seven selective primer combinations (EACG + M-CCG, E-ACT +M-CCG, E-AGC + M-CCG, E-ACG + M-CTC, E-ACT + M-CTC, E-AGC + M-CTC, E-AGG + M-CCA) resulted in 330 scoreable markers. A large number of markers were obtained when families where analyzed separately from its performance. Genetic distances based on AFLP markers frequencies were used to construct a dendrogram among families. The best quality performer families grouped widely separated from the worst performers, sharing 61.63% of their genetic elements. In volume, worst performer families grouped sharing 45.85% of their genetic elements.