Steven Gregory Ralph

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We report the draft genome of the black cottonwood tree, Populus trichocarpa. Integration of shotgun sequence assembly with genetic mapping enabled chromosome-scale reconstruction of the genome. More than 45,000 putative protein-coding genes were identified. Analysis of the assembled genome revealed a whole-genome duplication event; about 8000 pairs of(More)
Cold acclimation in conifers is a complex process, the timing and extent of which reflects local adaptation and varies widely along latitudinal gradients for many temperate and boreal tree species. Despite their ecological and economic importance, little is known about the global changes in gene expression that accompany autumn cold acclimation in conifers.(More)
Traditionally, simple sequence repeat (SSR) markers have been developed from libraries of genomic DNA. However, the large, repetitive nature of conifer genomes makes development of robust, single-copy SSR markers from genomic DNA difficult. Expressed sequence tags (ESTs), or sequences of messenger RNA, offer the opportunity to exploit single, low-copy,(More)
Stem-boring insects and methyl jasmonate (MeJA) are thought to induce similar complex chemical and anatomical defenses in conifers. To compare insect- and MeJA-induced terpenoid responses, we analyzed traumatic oleoresin mixtures, emissions of terpenoid volatiles, and expression of terpenoid synthase (TPS) genes in Sitka spruce (Picea sitchensis) following(More)
Many drugs of natural origin are hydrophobic and can pass through cell membranes. Hydrophobic molecules must be susceptible to active efflux systems if they are to be maintained at lower concentrations in cells than in their environment. Multi-drug resistance (MDR), often mediated by intrinsic membrane proteins that couple energy to drug efflux, provides(More)
Forestry is a valuable natural resource for many countries. Rapid production of large quantities of genetically improved and uniform seedlings for restocking harvested lands is a key component of sustainable forest management programs. Clonal propagation through somatic embryogenesis has the potential to meet this need in conifers and can offer the added(More)
Analysis of expressed sequence tags (ESTs) and full-length (FL)cDNAs from species of spruce (Picea spp.) revealed a family of 35 unique dirigent proteins (DIR) and DIR-like proteins. Phylogenetic analysis indicates the spruce DIR and DIR-like genes cluster into three distinct subfamilies, DIR-a, DIR-b/d, and DIR-f, of a larger plant DIR and DIR-like gene(More)
Studying lignin-biosynthetic-pathway mutants and transgenics provides insights into plant responses to perturbations of the lignification system, and enhances our understanding of normal lignification. When enzymes late in the pathway are downregulated, significant changes in the composition and structure of lignin may result. NMR spectroscopy provides(More)
Conifers are resistant to attack from a large number of potential herbivores or pathogens. Previous molecular and biochemical characterization of selected conifer defence systems support a model of multigenic, constitutive and induced defences that act on invading insects via physical, chemical, biochemical or ecological (multitrophic) mechanisms. However,(More)
Members of the pine family (Pinaceae), especially species of spruce (Picea spp.) and pine (Pinus spp.), dominate many of the world's temperate and boreal forests. These conifer forests are of critical importance for global ecosystem stability and biodiversity. They also provide the majority of the world's wood and fiber supply and serve as a renewable(More)