A natural expression variant reveals a novel mechanism of insect resistance in boreal forest trees.
ABSTRACT: We report the discovery of a beta-glucosidase gene (Pgβglu-1) whose expression underpins natural resistance to a major forest pest, the spruce budworm (SBW) in white spruce (Picea glauca (Voss.) Moench). We performed a microarray experiment to compare resistant (R) and non-resistant (N-R) trees. Pgβglu-1 transcripts levels uniquely were up to 1000 times higher in phenotypically resistant trees and correlated with accumulation of acetophenones compounds that reduce SBW development. These resistance traits were heritable, temporally correlated with the emergence of the most damaging larval stages and were highly variable in the natural population across a large geographic area. The recombinant gene product specifically catalyzed the release of biologically active acetophenones from their glucoside precursors. SBW outbreaks have become more frequent and intense; therefore, the phenotypic diversity resulting from variation in Pgβglu-1 expression may be a key for the adaptability of spruce populations. Transcriptome profiling was carried out with needles from 7 resistant and 7 non-resistant trees (harvested on June 17th, 2010), and 3 samples per tree (n=42) with a custom microarray developed for spruce species and comprising oligonucleotide probes for 23,853 unique P. glauca gene sequences (Raherison et al., 2012).
Project description:The goal is to identify tissue specific patterns of expression in Picea glauca seedlings One-color comparison of seven tissues of white spruce. Four biological repetitions per tissue (non-related trees), repeated in two channels as technical replicates, for a total of 56 slides.
Project description:The goal is to look at changes in the pattern of expression of the xylem transcriptome through the growth season in two spruces (Picea glauca and Picea abies). One-color comparison of active xylem collected in June, July, August and September, in two spruce species. Six biological repetitions per time point and specie, for a total of 48 slides.
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 goal is to examine the molecular aspects underpinning somatic embryogenesis (SE) within shoot tissues of adult white spruce trees by conducting transcriptome-wide expression profiling of shoot explants taken from responsive and nonresponsive genotypes. One-color analysis of vegetative buds in somatic embryogenesis responsive and nonresponsive genotypes, before and after 7 days of SE induction. There are 5 biological replicates for each of the 4 combinations of genotype/time of induction for a total of 20 slides. Each replicate is comprised of a pool of 6 buds.
Project description:The goal of this experiment is to evaluate the potential for utilising this oligonucleotide microarray in other species and genera of the Pinaceae family by using comparative RNA hybridizations in four different spruces (Picea spp), two pines (Pinus spp.) and a larch (Larix laricina), across two tissues, xylem and phelloderm. One-color comparison of 7 conifer species in 2 tissue types: xylem and phelloderm. Between 4 and 28 biological repetitions per sample type, depending on the species, for a total of 142 slides.
Project description:A small database of transcription profiles called PgGenExpress was developed from over 150 hybridizations spanning eight major tissue types. In total, transcripts were detected for 92% of the genes on the microarray, in at least one tissue. Non-annotated genes were predominantly expressed at low levels in fewer tissues than genes of known or predicted function. Diversity of expression within gene families may be rapidly assessed from PgGenExpress. In conifer trees, dehydrins and late embryogenesis (LEA) osmotic regulation proteins occur in large gene families compared to angiosperms. Strong contrasts and low diversity was observed in the dehydrin family, while diverse patterns suggested a greater degree of diversification among LEAs. This is a one-color meta-analysis of tissues from 5 separate experiments. There are 8 different tissue types. Each tissue is represented by a variable number of slides, each slide being a biological repetition, for a total of 149 slides.
Project description:Heritable variation in gene expression has been largely studied in model organisms by taking advantage of pure and inbred lines. Comparative studies on organisms with contrasting evolutionary history, population size and genome architecture have been hindered by practical considerations, as many of these species are poorly suited for breeding. We have developed a method for determining expression variation in an undomesticated tree species by directly measuring the segregation of gene expression in the haploid meiotic products of a single diploid individual. We show the utility of our approach by identifying expression variation that segregates consistent with one causal variant and identify an unexpectedly large number of these Mendelian expression traits. The megagametophyte approach opens the doors for the application of genetical genomics approaches in a large number of undomesticated plant species. Transcriptomics data from 18 megagametophytes of two unrelated mother trees. In tree 80112, all of the 18 megagametophytes were analyzed on to different microarrays with two different dyes. In tree 77111, 16 megagametophytes were replicated as above.