Project description:Tree ring features are affected by environmental factors and therefore are the basis for dendrochronological studies to reconstruct past environmental conditions. Oak wood often provides the data for these studies because of the durability particularly of oak heartwood and, hence the availability of samples spanning long time periods of the distant past. Wood formation is regulated in part by epigenetic mechanisms such as DNA methylation. Studies in the methylation state of DNA preserved in oak heartwood thus could identify epigenetic tree ring features informing on past environmental conditions. We investigated the feasibility of such studies using heartwood samples core-drilled from the trunks of standing oak trees spanning the AD 1776-2014. Heartwood contains little DNA, and large amounts of phenolic compounds known to hinder the preparation of high-throughput sequencing libraries. We sequenced whole-genome and DNA methylome libraries for oak heartwood up to 100 and 50 years of age, respectively. However, only 56 genomic regions with sufficient coverage for quantitative methylation analysis were identified, suggesting that the high-throughput sequencing of DNA will be in principal feasible for wood formed <100 years ago is impeded by the reduction in library complexity caused by the bisulfite treatment used to generate the oak methylome.
Project description:Acute Oak Decline (AOD) is a decline-disease currently spreading in Britain, threatening oak trees. Here, we analyze and compare the proteomes of inner bark tissue sampled from oak stems of trees symptomatic with AOD and non-symptomatic trees.
Project description:Environmental variation along the geographical space can shape populations by natural selection. In the context of global warming and changing precipitation regimes, it is crucial to understand the role of environmental heterogeneity in tropical trees adaptation, given their disproportional contribution to water and carbon biogeochemical cycles. Here, we investigated how heterogeneity in freshwater availability along tropical wetlands has influenced molecular variations of the black mangrove (Avicennia germinans). A total of 57 trees were sampled at seven sites differing markedly in precipitation regime and riverine freshwater inputs. Using 2,297 genome‐wide single nucleotide polymorphic markers, we found signatures of natural selection by the association between variations in allele frequencies and environmental variables, including the precipitation of the warmest quarter and the annual precipitation. Additionally, we found candidate loci for selection based on statistical deviations from neutral expectations of interpopulation differentiation. Most candidate loci within transcribed sequences were functionally associated with central aspects of drought tolerance or plant response to drought. Moreover, our results suggest the occurrence of the rapid evolution of a population, probably in response to sudden and persistent limitations in plant access to soil water, following a road construction in 1974. Observations supporting rapid evolution included the reduction in tree size and changes in allele frequencies and in transcript expression associated with increased drought tolerance through the accumulation of osmoprotectants and antioxidants, biosynthesis of cuticles, protection against protein degradation, stomatal closure, photorespiration and photosynthesis. We describe a major role of spatial heterogeneity in freshwater availability in the specialization of this typically tropical tree.
Project description:The transcriptome of Phanerochaete chrysosporium control mycelium was compared to the transcriptome of mycelium grown on oak acetonic extractives containing medium. The array probes were designed from gene models taken from the Joint Genome Institute (JGI, Department of Energy) Phanerochaete chrysosporium genome sequence version 1. The aim of this study was to determine gene expression changes in Phanerochaete chrysosporium grown on oak extract with a special focus on detoxification systems.
Project description:The periderm is basic for land plants due to its protective role during radial growth, which is achieved by the polymers deposited in the cell walls. Despite the research on the topic has unravelled the role of several enzymes and transcription factors, many questions remain open, especially those regarding cell development. Here we use the outer bark of cork oak (cork), holm oak (rhytidome), and their natural hybrids’ to further understand the mechanisms underlying periderm development. Cork is an outstanding model as it consists of a thick and very homogeneous periderm produced by a permanent mother-cell layer (phellogen). Conversely, holm oak contains a more heterogeneous bark including several thin periderms mixed with phloem, also known as a rhytidome. The inclusion of hybrid samples showing rhytidome-type and cork-type barks is valuable to approach cork development, allowing an accurate identification of candidate genes and processes. The present study underscores that biotic stress and cell death signalling are enhanced in rhytidome-type barks while lipid metabolism and cell cycle are enriched in cork-type barks. Based on the DEGs most expressed related to development, we highlight that cell division, cell expansion, and cell differentiation could account for the differences found between cork and rhytidome-type barks.
Project description:Expression diversity of P. ramorum isolates belonging to the NA1 clonal lineage growing on solid CV8 was examined. We found that phenotypes and transcriptomes change when isolates were passing through oak trees.
Project description:Drought is considered as a threat to the sustainability of Mediterranean forests and, of the agro-silvo-pastoral “dehesa” system. Holm oak (Quercus ilex L.) is one of the most representative species of these ecosystems and this abiotic stress causes a high tree mortality rate, being more accused at the seedling stage. In this study, an integrative analysis of transcriptome and proteome in leaves of Q. ilex seedlings under drought conditions was carried out to identify gene products involved in the metabolic pathways related to drought tolerant mechanisms.
Project description:Iso-Seq "full length" transcript sequences were used as one of many guides informing gene model annotation of the Valley Oak genome sequence.
Project description:Trees establish a symbiotic relationship with specialized soil fungi, called ectomycorrhizae, which is essential for nutrition, growth and health of temperate forest ecosystems. Understanding the mechanisms governing the establishment and functioning of ectomycorrhiza is important because of the role of forests in sequestering CO2 and also to develop ways to optimize tree productivity and sustainability. Here, we investigated the response of an oak species to ectomycorrhiza formation using a two dimensional differential in gel electrophoresis (2D-DIGE) and MALDI-TOF/TOF mass spectrometry proteomics approach. At the root level, changes in the abundance of 34 unique oak proteins were detected and revealed proteins involved in carbon and energy metabolism, protein processing and degradation, response to oxidative stress, lipid metabolism/transport, nitrogen and phosphorous assimilation and cell wall modification. Proteins supporting the importance of the secretory pathway functioning, in particular of the endoplasmic reticulum, during ectomycorrhiza functioning were identified. These proteins were identified as components of the endoplasmic reticulum folding/chaperoning machinery and proteins involved in the ER quality control system. This study constitutes an important contribution for the understanding of the mechanisms underlying the response of plants to ectomycorrhizal symbiosis establishment.