| 1. |
- Rönnberg Wästljung, Ann-Christin, et al.
(författare)
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Optimized utilization of Salix—Perspectives for the genetic improvement toward sustainable biofuel value chains
- 2022
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Ingår i: Global Change Biology Bioenergy. - : John Wiley and Sons Inc. - 1757-1693 .- 1757-1707. ; 14:10, s. 1128-144
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Tidskriftsartikel (refereegranskat)abstract
- Bioenergy will be one of the most important renewable energy sources in the conversion from fossil fuels to bio-based products. Short rotation coppice Salix could be a key player in this conversion since Salix has rapid growth, positive energy balance, easy to manage cultivation system with vegetative propagation of plant material and multiple harvests from the same plantation. The aim of the present paper is to provide an overview of the main challenges and key issues in willow genetic improvement toward sustainable biofuel value chains. Primarily based on results from the research project “Optimized Utilization of Salix” (OPTUS), the influence of Salix wood quality on the potential for biofuel use is discussed, followed by issues related to the conversion of Salix biomass into liquid and gaseous transportation fuels. Thereafter, the studies address genotypic influence on soil carbon sequestration in Salix plantations, as well as on soil carbon dynamics and climate change impacts. Finally, the opportunities for plant breeding are discussed using willow as a resource for sustainable biofuel production. Substantial phenotypic and genotypic variation was reported for different wood quality traits important in biological (i.e., enzymatic and anaerobic) and thermochemical conversion processes, which is a prerequisite for plant breeding. Furthermore, different Salix genotypes can affect soil carbon sequestration variably, and life cycle assessment illustrates that these differences can result in different climate mitigation potential depending on genotype. Thus, the potential of Salix plantations for sustainable biomass production and its conversion into biofuels is shown. Large genetic variation in various wood and biomass traits, important for different conversion processes and carbon sequestration, provides opportunities to enhance the sustainability of the production system via plant breeding. This includes new breeding targets in addition to traditional targets for high yield to improve biomass quality and carbon sequestration potential. © 2022 The Authors.
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| 2. |
- Adler, Anneli, et al.
(författare)
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Variation of growth and phenology traits in poplars planted in clonal trials in Northern Europe-implications for breeding
- 2021
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Ingår i: BioEnergy Research. - : Springer Science and Business Media LLC. - 1939-1234 .- 1939-1242. ; 14, s. 426-444
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Tidskriftsartikel (refereegranskat)abstract
- The increased demand for wood to replace oil-based products with renewable products has lifted focus to the Baltic Sea region where the environment is favorable for woody biomass growth. The aim of this study was to estimate broad-sense heritabilities and genotype-by-environment (GxE) interactions in growth and phenology traits in six climatically different regions in Sweden and the Baltics. We tested the hypothesis that both bud burst and bud set have a significant effect on the early growth of selected poplar clones in Northern Europe. Provenance hybrids of Populus trichocarpa adapted to the Northern European climate were compared to reference clones with adaptation to the Central European climate. The volume index of stemwood was under low to medium genetic control with heritabilities from 0.22 to 0.75. Heritabilities for phenology traits varied between 0.31 and 0.91. Locally chosen elite clones were identified. GxE interactions were analyzed using pairwise comparisons of the trials. Three different breeding zones for poplars between the latitudes of 55 degrees N and 60 degrees N in the Baltic Sea Region were outlined. The studied provenance hybrids with origin from North America offer a great possibility to broaden the area with commercial poplar plantations in Northern Europe and further improve the collection of commercial clones to match local climates. We conclude that phenology is an important selection criterion after growth.
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| 3. |
- Almeida, Pedro, et al.
(författare)
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Genome assembly of the basket willow, Salix viminalis, reveals earliest stages of sex chromosome expansion
- 2020
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Ingår i: BMC Biology. - : Springer Science and Business Media LLC. - 1741-7007. ; 18:1
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundSex chromosomes have evolved independently multiple times in eukaryotes and are therefore considered a prime example of convergent genome evolution. Sex chromosomes are known to emerge after recombination is halted between a homologous pair of chromosomes, and this leads to a range of non-adaptive modifications causing gradual degeneration and gene loss on the sex-limited chromosome. However, the proximal causes of recombination suppression and the pace at which degeneration subsequently occurs remain unclear.ResultsHere, we use long- and short-read single-molecule sequencing approaches to assemble and annotate a draft genome of the basket willow, Salix viminalis, a species with a female heterogametic system at the earliest stages of sex chromosome emergence. Our single-molecule approach allowed us to phase the emerging Z and W haplotypes in a female, and we detected very low levels of Z/W single-nucleotide divergence in the non-recombining region. Linked-read sequencing of the same female and an additional male (ZZ) revealed the presence of two evolutionary strata supported by both divergence between the Z and W haplotypes and by haplotype phylogenetic trees. Gene order is still largely conserved between the Z and W homologs, although the W-linked region contains genes involved in cytokinin signaling regulation that are not syntenic with the Z homolog. Furthermore, we find no support across multiple lines of evidence for inversions, which have long been assumed to halt recombination between the sex chromosomes.ConclusionsOur data suggest that selection against recombination is a more gradual process at the earliest stages of sex chromosome formation than would be expected from an inversion and may result instead from the accumulation of transposable elements. Our results present a cohesive understanding of the earliest genomic consequences of recombination suppression as well as valuable insights into the initial stages of sex chromosome formation and regulation of sex differentiation.
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| 4. |
- Apuli, Rami-Petteri, et al.
(författare)
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The genetic basis of adaptation in phenology in an introduced population of Black Cottonwood (Populus trichocarpa, Torr. & Gray)
- 2021
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Ingår i: BMC Plant Biology. - : BioMed Central (BMC). - 1471-2229. ; 21
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Tidskriftsartikel (refereegranskat)abstract
- Background: Entering and exiting winter dormancy present important trade-offs between growth and survival at northern latitudes. Many forest trees display local adaptation across latitude in traits associated with these phenology transitions. Transfers of a species outside its native range introduce the species to novel combinations of environmental conditions potentially requiring different combinations of alleles to optimize growth and survival. In this study, we performed genome wide association analyses and a selection scan in a P. trichocarpa mapping population derived from crossings between clones collected across the native range and introduced into Sweden. GWAS analyses were performed using phenotypic data collected across two field seasons and in a controlled phytotron experiment.Results: We uncovered 584 putative candidate genes associated with spring and autumn phenology traits as well as with growth. Many regions harboring variation significantly associated with the initiation of leaf shed and leaf autumn coloring appeared to have been evolving under positive selection in the native environments of P. trichocarpa. A comparison between the candidate genes identified with results from earlier GWAS analyses performed in the native environment found a smaller overlap for spring phenology traits than for autumn phenology traits, aligning well with earlier observations that spring phenology transitions have a more complex genetic basis than autumn phenology transitions.Conclusions: In a small and structured introduced population of P. trichocarpa, we find complex genetic architectures underlying all phenology and growth traits, and identify multiple putative candidate genes despite the limitations of the study population.
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| 5. |
- Hallingbäck, Henrik, et al.
(författare)
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Genome-wide association mapping uncovers sex-associated copy number variation markers and female hemizygous regions on the W chromosome in Salix viminalis
- 2021
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Ingår i: BMC Genomics. - : Springer Science and Business Media LLC. - 1471-2164. ; 22
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Tidskriftsartikel (refereegranskat)abstract
- Background Sex chromosomes are in some species largely undifferentiated (homomorphic) with restricted sex determination regions. Homomorphic but different sex chromosomes are found in the closely related genera Populus and Salix indicating flexible sex determination systems, ideal for studies of processes involved in sex chromosome evolution. We have performed genome-wide association studies of sex and analysed sex chromosomes in a population of 265 wild collected Salix viminalis accessions and studied the sex determining locus. Results A total of 19,592 markers were used in association analyses using both Fisher's exact tests and a single-marker mixed linear model, which resulted in 48 and 41 sex-associated (SA) markers respectively. Across all 48 SA markers, females were much more often heterozygous than males, which is expected if females were the heterogametic sex. The majority of the SA markers were, based on positions in the S. purpurea genome, located on chromosome 15, previously demonstrated to be the sex chromosome. Interestingly, when mapping the genotyping-by-sequencing sequence tag harbouring the two SA markers with the highest significance to the S. viminalis genomic scaffolds, five regions of very high similarity were found: three on a scaffold that represents a part of chromosome 15, one on a scaffold that represents a part of chromosome 9 and one on a scaffold not anchored to the genome. Based on segregation differences of the alleles at the two marker positions and on differences in PCR amplification between females and males we conclude that females had multiple copies of this DNA fragment (chromosome 9 and 15), whereas males only had one (chromosome 9). We therefore postulate that the female specific sequences have been copied from chromosome 9 and inserted on chromosome 15, subsequently developing into a hemizygous W chromosome linked region. Conclusions Our results support that sex determination in S. viminalis is controlled by one locus on chromosome 15. The segregation patterns observed at the SA markers furthermore confirm that S. viminalis females are the heterogametic sex. We also identified a translocation from chromosome 9 to the W chromosome.
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| 6. |
- Ohlsson, Jonas, et al.
(författare)
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Co-digestion of salix and manure for biogas: importance of clone choice, coppicing frequency and reactor setup
- 2020
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Ingår i: Energies. - : MDPI AG. - 1996-1073. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- Animalmanure represents amajor source of renewable energy that can be converted into biogasusing anaerobic digestion. In order to most efficiently utilize this resource, it can be co-digested withenergy dense, high biomethanation potential feedstocks such as energy crops. However, such feedstockstypically require pretreatments which are not feasible for small-scale facilities.We investigated theuse of single-stage and the sequential co-digestion of comminuted but otherwise non-pretreated Salixwith animal manure, and further investigated the effects of coppicing frequency and clone choice onbiomethanation potential and the area requirements for a typical Swedish farm-scale anaerobic digesterusing Salix and manure as feedstock. In comparison with conventional single-stage digestion, sequentialdigestion increased the volumetric and specific methane production by 57% to 577 NmL L?1 d?1 and192 NmL (g volatile solids (VS))?1, respectively. Biomethanation potential was the highest for the twoyear-old shoots, although gains in biomass productivity suggest that every-third-year coppicing maybe a better strategy for supplying Salix feedstock for anaerobic digestion. The biomethane productionperformance of the sequential digestion of minimally pretreated Salix mirrors that of hydrothermallypretreated hardwoods and may provide an option where such pretreatments are not feasible.
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| 7. |
- Richards, Thomas, et al.
(författare)
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Quantitative genetic architecture of adaptive phenology traits in the deciduous tree, Populus trichocarpa (Torr. And Gray)
- 2020
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Ingår i: Heredity. - : Springer Science and Business Media LLC. - 0018-067X .- 1365-2540. ; 125, s. 449-458
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Tidskriftsartikel (refereegranskat)abstract
- In a warming climate, the ability to accurately predict and track shifting environmental conditions will be fundamental for plant survival. Environmental cues define the transitions between growth and dormancy as plants synchronise development with favourable environmental conditions, however these cues are predicted to change under future climate projections which may have profound impacts on tree survival and growth. Here, we use a quantitative genetic approach to estimate the genetic basis of spring and autumn phenology inPopulus trichocarpato determine this species capacity for climate adaptation. We measured bud burst, leaf coloration, and leaf senescence traits across two years (2017-2018) and combine these observations with measures of lifetime growth to determine how genetic correlations between phenology and growth may facilitate or constrain adaptation. Timing of transitions differed between years, although we found strong cross year genetic correlations in all traits, suggesting that genotypes respond in consistent ways to seasonal cues. Spring and autumn phenology were correlated with lifetime growth, where genotypes that burst leaves early and shed them late had the highest lifetime growth. We also identified substantial heritable variation in the timing of all phenological transitions (h(2) = 0.5-0.8) and in lifetime growth (h(2) = 0.8). The combination of additive variation and favourable genetic correlations in phenology traits suggests that populations of cultivated varieties of P. Trichocarpa may have the capability to adapt their phenology to climatic changes without negative impacts on growth.
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| 8. |
- Rönnberg Wästljung, Ann-Christin, et al.
(författare)
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Phenotypic plasticity in Populus trichocarpa clones across environments in the Nordic-Baltic region
- 2022
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Ingår i: Scandinavian Journal of Forest Research. - : Informa UK Limited. - 0282-7581 .- 1651-1891. ; 37, s. 1-5
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Tidskriftsartikel (refereegranskat)abstract
- Transition towards a bio-based society requires large amounts of woody biomass to be converted into biofuels and biomaterials. Populus species are good candidates for growth in short rotations, but there is a lack of climate-adapted plant material suitable for growth at the high latitudes of the Nordic-Baltic region. Here we studied the growth and phenology traits in 63 Populus trichocarpa clones earlier preliminary selected for growth at northern latitudes, in three different field sites; i.e. in central Sweden, eastern and western Latvia. The material showed moderate broad sense heritabilities, with high values for phenology traits, indicating opportunities for selection. Genotype x environment (g x e) interaction was identified for all traits, but the phenotypic correlation between pairs of sites provided more detailed information indicating the strength of the g x e interaction. The between-clone variation in plasticity was high, and we identified some clones showing a high and stable performance across the three sites. These clones are of particular interest for the commercial deployment and future breeding of Populus material for the Nordic-Baltic region.
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| 9. |
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