Biology subjects

Street, N.

Publications and source records attributed to Street, N..

4 recordsLinked to original sources

bioRxiv2021

Identification of genetic markers and wood properties that predict wood biorefinery potential in aspen bioenergy feedstock (Populus tremula).

BackgroundWood represents the majority of the biomass on land and constitutes a renewable source of biofuels and other bioproducts. However, wood is recalcitrant to bioconversion, raising a need for feedstock improvement in production of, for instance, biofuels. We investigated the properties of wood that affect bioconversion, as well as the underlying genetics, to help identify superior tree feedstocks for biorefining. ResultsWe recorded 65 wood-related and growth traits in a population of 113 natural aspen genotypes from Sweden. These traits included three growth and field performance traits, 20 traits for wood chemical composition, 17 traits for wood anatomy and structure, and 25 wood saccharification traits as indicators of bioconversion potential. Glucose release after saccharification with acidic pretreatment correlated positively with tree stem height and diameter and the carbohydrate content of the wood, and negatively with the content of lignin and the hemicellulose sugar units. Most of these traits displayed extensive natural variation within the aspen population and high broad-sense heritability, supporting their potential in genetic improvement of feedstocks towards improved bioconversion. Finally, a genome wide association study (GWAS) revealed 13 genetic loci for saccharification yield (on a whole tree biomass basis), with six of them intersecting with associations for either height or stem diameter of the trees. ConclusionsThe simple growth traits of stem height and diameter were identified as good predictors of wood saccharification yield in aspen trees. GWAS elucidated the underlying genetics, revealing putative genetic markers for bioconversion of bioenergy tree feedstocks.

plant biology↗

bioRxiv2019

Evidence for widespread selection in shaping the genomic landscape during speciation of Populus

Increasing our understanding of how various evolutionary processes drive the genomic landscape of variation is fundamental to a better understanding of the genomic consequences of speciation. However, the genome-wide patterns of within- and between-species variation have not been fully investigated in most forest tree species despite their global ecological and economic importance. Here, we use whole-genome resequencing data from four Populus species spanning the speciation continuum to reconstruct their demographic histories, investigate patterns of diversity and divergence, infer their genealogical relationships and estimate the extent of ancient introgression across the genome. Our results show substantial variation in these patterns along the genomes although this variation is not randomly distributed but is strongly predicted by the local recombination rates and the density of functional elements. This implies that the interaction between recurrent selection and intrinsic genomic features has dramatically sculpted the genomic landscape over long periods of time. In addition, our findings provide evidence that, apart from background selection, recent positive selection and long-term balancing selection are also crucial components in shaping patterns of genome-wide variation during the speciation process.

evolutionary biology↗

bioRxiv2019

GenIE-Sys: Genome Integrative Explorer System

There are an ever-increasing number of genomes being sequenced, many of which have associated RNA sequencing and other genomics data. The availability of user-friendly web-accessible mining tools ensures that these data repositories provide maximum benefit to the community. However, there are relatively few options available for setting up such standalone frameworks. We developed the Genome Integrative Explorer System (GenIE-Sys) to set up web resources to enable search, visualization and exploration of genomics data typically generated by a genome project.\n\nGenIE-Sys is implemented in PHP, JavaScript and Python and is freely available under the GNU GPL 3 public license. All source code is freely available at the GenIE-Sys website (https://geniesys.org) or GitHub (http://github.com/plantgenie/geniesys.git). Documentation is available at http://geniesys.readthedocs.io.

bioinformatics↗

bioRxiv2019

An Improved Genome Assembly of the European Aspen Populus tremula

Aspen (Populus tremula L.) is a widely distributed keystone species and a model system for forest tree genomics, with extensive resources developed for population genetics and genomics. Here we present an updated resource comprising a chromosome-scale assembly of P. tremula and population genetics and genomics data integrated into the PlantGenIE.org web resource. We demonstrate use of the diverse data types included to explore the genetic basis of natural variation in leaf size and shape as examples of traits with complex genetic architecture. We present a chromosome-scale genome assembly generated using long-read sequencing, optical and high-density genetic maps containing 39,894 annotated genes with functional annotations for 73,765 transcripts from 37,184 gene loci. We conducted whole-genome resequencing of the Ume[a] Aspen (UmAsp) collection comprising 227 aspen individuals. We utilised the assembly, the UmAsp re-sequencing data and existing whole genome re-sequencing data from the Swedish Aspen (SwAsp) and Scottish Aspen (ScotAsp) collections to perform genome-wide association analyses (GWAS) using Single Nucleotide Polymorphisms (SNPs) for leaf physiognomy phenotypes. We conducted Assay of Transposase Accessible Chromatin sequencing (ATAC-Seq) and identified genomic regions of accessible chromatin and subset SNPs to these regions, which improved the GWAS detection rate. We identified candidate long non-coding RNAs in leaf samples and quantified their expression in an updated co-expression network (AspLeaf, available in PlantGenIE.org), which we further used to explore the functions of candidate genes identified from the GWAS. We examined synteny to the reference P. trichocarpa assembly and identified P. tremula-specific regions. Analysis of whole-genome duplication indicated differential substitution rates for the two Populus species, indicating more rapid evolution in P. tremula. A GWAS of 26 leaf physiognomy traits and all SNPs in each of the three aspen collections found significant associations for only two traits in ScotAsp collection and one in UmAsp, whereas subsetting SNPs to those in open chromatin regions revealed associations for a further four traits among all three aspen collections. The significant SNPs were associated with genes annotated for developmental and growth functions, which represent candidates for further study. Of particular interest was a 177-kbp region of chromosome 9 harbouring SNPs associated with multiple leaf phenotypes in ScotAsp, with the set of SNPs in linkage disequilibrium explaining 24 to 30 % of the phenotypic variation in leaf indent depth variation. We have incorporated the assembly, population genetics, genomics and leaf physiognomy GWAS data into the PlantGenIE.org web resource, including updating existing genomics data to the new genome version. This enables easy exploration and visualisation of the genomics data and exploration of GWAS results. We provide all raw and processed data used for the presented analyses to facilitate reuse in future studies.

genomics↗