Project description:The goal of this experiment is to assess tissue preferential transcript accumulation and fold difference between two tissues that support secondary vascular growth in three spruces: Picea glauca, Picea sitchensis and Picea mariana. Tissues compared are secondary xylem (wood forming tissue located on the internal side of the cambial meristem) and phelloderm (composite sample of the phloem and phelloderm tissues located on the outer side of the cambial meristem). One-color comparison of 3 spruce species in 2 tissue types: xylem and phelloderm. 20 biological repetitions per tissue for Picea glauca and 15 for Picea sitchensis and Picea mariana, for a total of 100 slides.
Project description:The current study uses a transcriptomic approach to identify genes associated with differences in wood density, that are likely to be of value as candidate genes in Sitka breeding programmes for improved wood density. Following extensive wood density analysis from a Sitka spruce (Picea sitchensis (Bong) Carr.) field grown clonal trial, three detailed microarray studies were conducted to compare the transcriptome of cambial tissue from contrasting clonal lines with high and low wood density. Twenty five genes exhibited differential expression, reaching as high as 50 fold, in at least two of the three microarray experiments and this was verified using real-time PCR. Identified genes functioned in cell wall synthesis, transcriptional regulation and plant pathogen defence, amongst others. These results confirm the importance of previously-identified density-related genes, and highlight a number of novel genes with a putative role in wood quality. A wide range of processes influence wood density, but this study has allowed the identification of potential regulators in these pathways. Future studies may now use this information to understand the control of natural variation in wood density, and manipulate the expression of these genes to improve timber quality. The Sitka spruce (Picea sitchensis (Bong) Carr.) âExperiment 35â clonal trial was grown at Newcastleton, Scotland (OS grid reference: NY506881, latitude: 55.1847, longitude: -2.77892) and set up by Forest Research, an agency of the Forestry Commission, which has been described previously (Mboyi and Lee 1999). A total of 750 trees were established from cuttings taken in 1989 of genotypes belonging to 6 unrelated full-sib families with 8 genotypes per family and 15 replicate ramets per genotype. Cambial cell scrapes were taken in summer 2004 when trees were 15 years old. A 5x2cm section of bark was cut away at a height of 1.3m from the ground for each tree selected for microarray analysis. The exposed xylem was immediately excised using a clean sharp razor blade and snap frozen in liquid Nitrogen. Samples were transported to the laboratory and ground in liquid nitrogen using a chilled mortar and pestle and stored at -80oC prior to RNA extraction. RNA was extracted and microarray hybridisation performed as described within.
Project description:The current study uses a transcriptomic approach to identify genes associated with differences in wood density, that are likely to be of value as candidate genes in Sitka breeding programmes for improved wood density. Following extensive wood density analysis from a Sitka spruce (Picea sitchensis (Bong) Carr.) field grown clonal trial, three detailed microarray studies were conducted to compare the transcriptome of cambial tissue from contrasting clonal lines with high and low wood density. Twenty five genes exhibited differential expression, reaching as high as 50 fold, in at least two of the three microarray experiments and this was verified using real-time PCR. Identified genes functioned in cell wall synthesis, transcriptional regulation and plant pathogen defence, amongst others. These results confirm the importance of previously-identified density-related genes, and highlight a number of novel genes with a putative role in wood quality. A wide range of processes influence wood density, but this study has allowed the identification of potential regulators in these pathways. Future studies may now use this information to understand the control of natural variation in wood density, and manipulate the expression of these genes to improve timber quality.
Project description: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. In spite of their ecological and economic importance, little is known about the global changes in gene expression that accompany autumn cold acclimation in conifers. Using three populations of Sitka spruce (Picea sitchensis) spanning the species range, and a Picea cDNA microarray with 21,840 unique elements, we monitored within and among-population gene expression during the fall. Microarray data were validated for selected genes using real-time PCR. Similar numbers of genes were significantly two-fold upregulated (1,257) and downregulated (967) between late summer and early winter. Among those upregulated were dehydrins, pathogenesis-related/antifreeze genes, carbohydrate and lipid metabolism genes, and genes involved in signal transduction and transcriptional regulation. Among-population microarray hybridizations at early and late autumn time points revealed substantial variation in the autumn transcriptome, some of which may reflect local adaptation. Our results demonstrate the complexity of cold acclimation in conifers, highlight similarities and differences to cold tolerance in annual plants, and provide a solid foundation for functional and genetic studies of this important adaptive process in conifers. Keywords: Time course
Project description:White pine weevil is a major pest of conifers in North America, especially for Spruce trees. Constitutive defenses are important in understanding defense mechanisms because they constitute the initial barrier to attacks by weevils and other pests. Resistant and susceptible trees exhibit constitutive differences in spruce. To improve our knowledge of their genetic basis, we compared the constitutive expression levels of 17,825 genes between 20 resistant and 20 susceptible trees in interior spruce (Picea glauca).