Project description:Bark beetles (Coleoptera: Scolytinae) are pests of many forests around the world. The mountain pine beetle (MPB), Dendroctonus ponderosae Hopkins, is a significant pest of western North American pine forests. The MPB is able to overcome the defences of pine trees through pheromone-assisted aggregation that results in a mass attack of host trees. These pheromones, both male and female produced, are believed to be biosynthesized in the midgut and/or fat body of these insects. We have used transcriptomics (RNA-seq) to identify transcripts differentially expressed between sexes and between tissues, with juvenile hormone III treatment, which is known to induce pheromone biosynthesis.
Project description:Bursaphelenchus xylophilus (pinewood nematode, PWN) is a causal agent of pine wilt disease and results in economic and environmental losses in pine forests. The establishment of systemic acquired resistance (SAR) provides positive capacities to control PWN. We selected two SAR elicitors, acibenzolar-S-methyl (ASM) and methyl salicylic acid (MeSA), which effectively inhibited disease symptoms on PWN-infected pine trees. To understand dynamic interactions between pine host and PWN under SAR state, we characterized in vivo transcriptomes of pine trees infected by B. xylophilus according to the ASM and MeSA treatment. After distilled water treatment, pine trees infected by B. xylophilus was used as a negative control.
Project description:Bursaphelenchus xylophilus (pinewood nematode, PWN) is the causal agent of pine wilt disease, causing economic and environmental losses in pine forests. The establishment of systemic acquired resistance (SAR) offers positive prospects for PWN control. We chose Bacillus subtilis JCK-1398, which effectively mitigated disease symptoms in PWN-infected pine trees. To elucidate the molecular responses involved in increased SAR according to B. subtilis JCK-1398 treatment, we characterized the in vivo transcriptomes of pine trees infected by PWN with B. subtilis JCK-1398 treatment. Additionally, pine trees infected by PWN after Tween20 treatment were used as a negative control.
Project description:To identify specific gene networks induced in host roots by C. geophilum, we inoculated seedlings of Scots pine simultaneously with C. geophilum and either Suillus granulatus or Rhizopogon roseolus, two common ECM fungi associated to pines. We then measured the differential expression of Scots pine genes in the respective mycorrhizas using oligoarrays. We performed 14 hybridizations (NimbleGen) with samples derived from Pinus sylvestris mycorrhiza with Cenococcum geophilum, Rhizopogon roseolus or Suillus granulatus (3 biological replicates each), as well as from non-mycorrhizal control roots (two replicates). Only the Pinus-derived sequences from the array were considered for this analysis. All samples were labeled with Cy3.
Project description:In conifer forests of Northern Europe, a pathogenic fungus Heterobasidion annosum attacks the roots of Scots pine and causes mortality. Trees with infection grow slower and produce less timber with reduced quality. Despite applied control methods, such as switching tree species to a non-host species, or stump treatment, root and butt rot continues to be a serious forest health problem. Disease resistance breeding is a less-applied control method which has potential to improve tree health. However, neither conifer genotypes with absolute resistance to Heterobasidion sp. nor robust selection markers for resistance breeding have been found. We studied the responses of various Scots pine genotypes to Heterobasidion annosum infection and mechanic damage in drained peatland. Stems and roots of mature naturally regenerated Scots pine trees growing in drained peatland were either artificially infected with H. annosum or wounded and inoculated with sterile inoculum. Untreated trees from the study sites served as controls. Responses of different Scots pine genotypes to pathogen infection as determined by lesion size were recorded from samples harvested four months after inoculation, and least susceptible and highly susceptible genotypes were selected from the study material. Analysis of terpenoids from both least susceptible and highly susceptible pine genotypes by gas chromatography coupled with mass spectrometry indicates that some monoterpenes and sesquiterpenes are differentially induced depending on the susceptibility level. Transcriptomic microarray analysis was therefore conducted with RNA from stems of the least susceptible and highly susceptible Scots pine genotypes. Gene expression data from cDNA microarray were analysed by comparisons between the treatments, and the genotypes with different resistance level. The aim of the study is to highlight transcripts specific to differing levels of susceptibility.
Project description:Mycorrhiza helper bacteria (MHB) promote the formation of ectomycorrhizae between tree roots and ectomycorrhizal fungi. Despite the high relevance of MHB for forestry and for sustainable tree production in tree nurseries, little is known about the properties of the bacteria that contribute to their helper abilities. The MHB strain Pseudomonas fluorescens BBc6R8 is used as a model to study the mechanisms of the helper effect. We took advantage of new technologies to obtain, for the first time, the whole genome sequence of an MHB. Analyses reveal an important plasticity of the genome with numerous functions acquired by horizontal gene tranfer. Genome mining was combined with transcriptomic and mutagenesis approaches to reveal molecular determinants of the helper effect. The data suggest that the production of helper molecules is likely to be constitutive in vitro. The helper effect appears to be pleiotropic and to rely, for a substantial part, on trophic interactions. Despite its helper abilities, the bacterium is also able in specific conditions to outcompete ectomycorrhizal fungi and inhibit their growth. We conclude that the helper bacterium possess a broad range of properties whose expression depending on the biotic and abiotic conditions can result in either a beneficial, neutral or antagonistic interaction between the plant, the ectomycorrhizal fungus and the bacterium.
2014-06-12 | GSE38243 | GEO
Project description:Soil microbial community in Pine Invasion forests