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Wilkerson DG, Taskiran B, Carlson CH, Smart LB. Mapping the sex determination region in the Salix F1 hybrid common parent population confirms a ZW system in six diverse species. G3 GENES|GENOMES|GENETICS 2022; 12:6554199. [PMID: 35333299 PMCID: PMC9157088 DOI: 10.1093/g3journal/jkac071] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Accepted: 03/17/2022] [Indexed: 11/24/2022]
Abstract
Within the genus Salix, there are approximately 350 species native primarily to the northern hemisphere and adapted to a wide range of habitats. This diversity can be exploited to mine novel alleles conferring variation important for production as a bioenergy crop, but also to identify evolutionarily important genes, such as those involved in sex determination. To leverage this diversity, we created a mapping population by crossing 6 Salix species (Salix viminalis, Salix suchowensis, Salix integra, Salix koriyanagi, Salix udensis, and Salix alberti) to common male and female Salix purpurea parents. Each family was genotyped via genotyping-by-sequencing and assessed for kinship and population structure as well as the construction of 16 backcross linkage maps to be used as a genetic resource for breeding and selection. Analyses of population structure resolved both the parents and F1 progeny to their respective phylogenetic section and indicated that the S. alberti parent was misidentified and was most likely S.suchowensis. Sex determining regions were identified on Salix chromosome 15 in the female-informative maps for seven of the eight families indicating that these species share a common female heterogametic ZW sex system. The eighth family, S. integra × S. purpurea, was entirely female and had a truncated chromosome 15. Beyond sex determination, the Salix F1 hybrid common parent population (Salix F1 HCP) introduced here will be useful in characterizing genetic factors underlying complex traits, aid in marker-assisted selection, and support genome assemblies for this promising bioenergy crop.
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Affiliation(s)
- Dustin G Wilkerson
- Horticulture Section, School of Integrative Plant Sciences, Cornell University, Cornell AgriTech , Geneva, NY 14456, USA
| | - Bircan Taskiran
- Horticulture Section, School of Integrative Plant Sciences, Cornell University, Cornell AgriTech , Geneva, NY 14456, USA
| | - Craig H Carlson
- Horticulture Section, School of Integrative Plant Sciences, Cornell University, Cornell AgriTech , Geneva, NY 14456, USA
| | - Lawrence B Smart
- Horticulture Section, School of Integrative Plant Sciences, Cornell University, Cornell AgriTech , Geneva, NY 14456, USA
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Wilkerson DG, Crowell CR, Carlson CH, McMullen PW, Smart CD, Smart LB. Comparative transcriptomics and eQTL mapping of response to Melampsora americana in selected Salix purpurea F2 progeny. BMC Genomics 2022; 23:71. [PMID: 35065596 PMCID: PMC8783449 DOI: 10.1186/s12864-021-08254-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 12/10/2021] [Indexed: 11/20/2022] Open
Abstract
Background Melampsora spp. rusts are the greatest pathogen threat to shrub willow (Salix spp.) bioenergy crops. Genetic resistance is key to limit the effects of these foliar diseases on host response and biomass yield, however, the genetic basis of host resistance has not been characterized. The addition of new genomic resources for Salix provides greater power to investigate the interaction between S. purpurea and M. americana, species commonly found in the Northeast US. Here, we utilize 3′ RNA-seq to investigate host-pathogen interactions following controlled inoculations of M. americana on resistant and susceptible F2S. purpurea genotypes identified in a recent QTL mapping study. Differential gene expression, network analysis, and eQTL mapping were used to contrast the response to inoculation and to identify associated candidate genes. Results Controlled inoculation in a replicated greenhouse study identified 19 and 105 differentially expressed genes between resistant and susceptible genotypes at 42 and 66 HPI, respectively. Defense response gene networks were activated in both resistant and susceptible genotypes and enriched for many of the same defense response genes, yet the hub genes of these common response modules showed greater mean expression among the resistant plants. Further, eight and six eQTL hotspots were identified at 42 and 66 HPI, respectively. The combined results of three analyses highlight 124 candidate genes in the host for further analysis while analysis of pathogen RNA showed differential expression of 22 genes, two of which are candidate pathogen effectors. Conclusions We identified two differentially expressed M. americana transcripts and 124 S. purpurea genes that are good candidates for future studies to confirm their role in conferring resistance. Supplementary Information The online version contains supplementary material available at 10.1186/s12864-021-08254-1.
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Gouker FE, Carlson CH, Zou J, Evans L, Crowell CR, Smart CD, DiFazio SP, Smart LB. Sexual dimorphism in the dioecious willow Salix purpurea. AMERICAN JOURNAL OF BOTANY 2021; 108:1374-1387. [PMID: 34406658 DOI: 10.1002/ajb2.1704] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Accepted: 01/28/2021] [Indexed: 06/13/2023]
Abstract
PREMISE The evolution of sex chromosomes is driven by sexual dimorphism, yet it can be challenging to document sexually dimorphic traits in dioecious plant species. At the genetic level, sexual dimorphism can be identified through sequence variation between females and males associated with sexually antagonistic traits and different fitness optima. This study aims to examine sexual dimorphism for 26 traits in three populations of Salix purpurea (a diversity panel and F1 and F2 populations) and determine the effect of the traits on biomass yield, a key trait in Salix bioenergy crops across multiple years, locations, and under manipulated growth conditions. METHODS Sexual dimorphism was evaluated for morphological, phenological, physiological, and wood composition traits in a diversity panel of unrelated S. purpurea accessions and in full-sib F1 and F2 families produced through controlled cross pollinations and grown in replicated field trials. RESULTS We observed sexual dimorphism in the timing of development for several traits that were highly predictive of biomass yield across three populations of S. purpurea. Across all populations and years surveyed, males had significantly shallower branching angle. Male plants highly predictive of biomass yield across three populations of S. purpurea also accumulated more nitrogen under fertilizer amendment as measured by SPAD in the diversity panel and had greater susceptibility to the rust fungus Melampsora americana in the F2 family. Allometric modelling of biomass yield showed an effect of sex and of location on the interaction between yield and stem height. CONCLUSIONS These results provide evidence of sexual dimorphism for certain traits in S. purpurea that may be involved in sex chromosome evolution.
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Affiliation(s)
- Fred E Gouker
- Horticulture Section, School of Integrative Plant Science, Cornell University, Cornell AgriTech, Geneva, NY, 14456, USA
| | - Craig H Carlson
- Horticulture Section, School of Integrative Plant Science, Cornell University, Cornell AgriTech, Geneva, NY, 14456, USA
| | - Junzhu Zou
- Horticulture Section, School of Integrative Plant Science, Cornell University, Cornell AgriTech, Geneva, NY, 14456, USA
- Research Institute of Forestry, Chinese Academy of Forestry, Beijing, 100091, China
| | - Luke Evans
- Department of Biology, West Virginia University, Morgantown, WV, 26506, USA
| | - Chase R Crowell
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Cornell AgriTech, Geneva, NY, 14456, USA
| | - Christine D Smart
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Cornell AgriTech, Geneva, NY, 14456, USA
| | - Stephen P DiFazio
- Department of Biology, West Virginia University, Morgantown, WV, 26506, USA
| | - Lawrence B Smart
- Horticulture Section, School of Integrative Plant Science, Cornell University, Cornell AgriTech, Geneva, NY, 14456, USA
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Carlson CH, Gouker FE, Crowell CR, Evans L, DiFazio SP, Smart CD, Smart LB. Joint linkage and association mapping of complex traits in shrub willow (Salix purpurea L.). ANNALS OF BOTANY 2019; 124:701-716. [PMID: 31008500 PMCID: PMC6821232 DOI: 10.1093/aob/mcz047] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Accepted: 03/08/2019] [Indexed: 05/25/2023]
Abstract
BACKGROUND AND AIMS Increasing energy demands and the necessity to reduce greenhouse gas emissions are key motivating factors driving the development of lignocellulosic crops as an alternative to non-renewable energy sources. The effects of global climate change will require a better understanding of the genetic basis of complex adaptive traits to breed more resilient bioenergy feedstocks, like willow (Salix spp.). Shrub willow is a sustainable and dedicated bioenergy crop, bred to be fast-growing and high-yielding on marginal land without competing with food crops. In a rapidly changing climate, genomic advances will be vital for the sustained improvement of willow and other non-model bioenergy crops. Here, joint genetic mapping was used to exploit genetic variation garnered from both recent and historical recombination events in S. purpurea. METHODS A panel of North American naturalized S. purpurea accessions and full-sib F2S. purpurea population were genotyped and phenotyped for a suite of morphological, physiological, pest and disease resistance, and wood chemical composition traits, collected from multi-environment and multi-year replicated field trials. Controlling for population stratification and kinship in the association panel and spatial variation in the F2, a comprehensive mixed model analysis was used to dissect the complex genetic architecture and plasticity of these important traits. KEY RESULTS Individually, genome-wide association (GWAS) models differed in terms of power, but the combined approach, which corrects for yearly and environmental co-factors across datasets, improved the overall detection and resolution of associated loci. Although there were few significant GWAS hits located within support intervals of QTL for corresponding traits in the F2, many large-effect QTL were identified, as well as QTL hotspots. CONCLUSIONS This study provides the first comparison of linkage analysis and linkage disequilibrium mapping approaches in Salix, and highlights the complementarity and limits of these two methods for elucidating the genetic architecture of complex bioenergy-related traits of a woody perennial breeding programme.
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Affiliation(s)
- Craig H Carlson
- Horticulture Section, School of Integrative Plant Science, Cornell University, Cornell AgriTech, Geneva, NY, USA
| | - Fred E Gouker
- Horticulture Section, School of Integrative Plant Science, Cornell University, Cornell AgriTech, Geneva, NY, USA
| | - Chase R Crowell
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Cornell AgriTech, Geneva, NY, USA
| | - Luke Evans
- Institute for Behavioral Genetics and Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO, USA
| | - Stephen P DiFazio
- Department of Biology, West Virginia University, Morgantown, WV, USA
| | - Christine D Smart
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Cornell AgriTech, Geneva, NY, USA
| | - Lawrence B Smart
- Horticulture Section, School of Integrative Plant Science, Cornell University, Cornell AgriTech, Geneva, NY, USA
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Hallingbäck HR, Berlin S, Nordh NE, Weih M, Rönnberg-Wästljung AC. Genome Wide Associations of Growth, Phenology, and Plasticity Traits in Willow [ Salix viminalis (L.)]. FRONTIERS IN PLANT SCIENCE 2019; 10:753. [PMID: 31249579 PMCID: PMC6582754 DOI: 10.3389/fpls.2019.00753] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Accepted: 05/23/2019] [Indexed: 05/10/2023]
Abstract
The short rotation biomass crop willow (Salix genera) has been of interest for bioenergy but recently also for biofuel production. For a faster development of new varieties molecular markers could be used as selection tool in an early stage of the breeding cycle. To identify markers associated with growth traits, genome-wide association mapping was conducted using a population of 291 Salix viminalis accessions collected across Europe and Russia and a large set of genotyping-by-sequencing markers. The accessions were vegetatively propagated and planted in replicated field experiments, one in Southern Sweden and one in Central Sweden. Phenology data, including bud burst and leaf senescence, as well as different growth traits were collected and measured repeatedly between 2010 and 2017 at both field environments. A value of the plasticity for each accession was calculated for all traits that were measured the same year in both environments as the normalized accession value in one environment subtracted by the corresponding value in the other environment. Broad-sense accession heritabilities and narrow-sense chip heritabilities ranged from 0.68 to 0.95 and 0.45 to 0.99, respectively for phenology traits and from 0.56 to 0.85 and 0.24 to 0.97 for growth traits indicating a considerable genetic component for most traits. Population structure and kinship between accessions were taken into account in the association analyses. In total, 39 marker-trait associations were found where four were specifically connected to plasticity and interestingly one particular marker was associated to several different plasticity growth traits. Otherwise association consistency was poor, possibly due to accession by environment interactions which were demonstrated by the low structure adjusted accession correlations across environments (ranging from 0.40 to 0.58). However, one marker association with biomass fresh weight was repeatedly observed in the same environment over two harvest years. For some traits where several associations were found, the markers jointly explained over 20% of the accession variation. The result from this study using a population of unrelated accessions has given useful information about marker-trait associations especially highlighting marker-plasticity associations and genotype-by-environment interactions as important factors to take account of in future strategies of Salix breeding.
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Affiliation(s)
- Henrik R. Hallingbäck
- Department of Plant Biology, Uppsala BioCenter, Linnean Centre for Plant Biology, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Sofia Berlin
- Department of Plant Biology, Uppsala BioCenter, Linnean Centre for Plant Biology, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Nils-Erik Nordh
- Department of Crop Production Ecology, Linnean Centre for Plant Biology, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Martin Weih
- Department of Crop Production Ecology, Linnean Centre for Plant Biology, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Ann-Christin Rönnberg-Wästljung
- Department of Plant Biology, Uppsala BioCenter, Linnean Centre for Plant Biology, Swedish University of Agricultural Sciences, Uppsala, Sweden
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Identification of Quantitative Trait Loci Conditioning the Main Biomass Yield Components and Resistance to Melampsora spp. in Salix viminalis × Salix schwerinii Hybrids. Int J Mol Sci 2017; 18:ijms18030677. [PMID: 28327519 PMCID: PMC5372687 DOI: 10.3390/ijms18030677] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Revised: 02/27/2017] [Accepted: 03/16/2017] [Indexed: 11/17/2022] Open
Abstract
The biomass of Salix viminalis is the most highly valued source of green energy, followed by S. schwerinii, S. dasyclados and other species. Significant variability in productivity and leaf rust resistance are noted both within and among willow species, which creates new opportunities for improving willow yield parameters through selection of desirable recombinants supported with molecular markers. The aim of this study was to identify quantitative trait loci (QTLs) linked with biomass yield-related traits and the resistance/susceptibility of Salix mapping population to leaf rust. The experimental material comprised a mapping population developed based on S. viminalis × S. schwerinii hybrids. Phenotyping was performed on plants grown in a field experiment that had a balanced incomplete block design with 10 replications. Based on a genetic map, 11 QTLs were identified for plant height, 9 for shoot diameter, 3 for number of shoots and 11 for resistance/susceptibility to leaf rust. The QTLs identified in our study explained 3%–16% of variability in the analyzed traits. Our findings make significant contributions to the development of willow breeding programs and research into shrubby willow crops grown for energy.
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Pucholt P, Sjödin P, Weih M, Rönnberg-Wästljung AC, Berlin S. Genome-wide transcriptional and physiological responses to drought stress in leaves and roots of two willow genotypes. BMC PLANT BIOLOGY 2015; 15:244. [PMID: 26458893 PMCID: PMC4604075 DOI: 10.1186/s12870-015-0630-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Accepted: 09/29/2015] [Indexed: 05/25/2023]
Abstract
BACKGROUND Drought is a major environmental stress that can have severe impacts on plant productivity and survival. Understanding molecular mechanisms of drought responses is crucial in order to breed for drought adapted plant cultivars. The aim of the present study was to investigate phenotypic and transcriptional drought responses in two willow genotypes (520 and 592) originating from an experimental cross between S. viminalis × (S. viminalis × S. schwerinii). Willows are woody perennials in the Salicaceae plant family that are grown as bioenergy crops worldwide. METHODS An experiment was conducted where plants were exposed to drought and different eco-physiological parameters were assessed. RNA-seq data was furthermore generated with the Illumina technology from root tips and leaves from plants grown in drought and well-watered (WW) conditions. The RNA-seq data was assembled de novo with the Trinity assembler to create a reference gene set to which the reads were mapped in order to obtain differentially expressed genes (DEGs) between the drought and WW conditions. To investigate molecular mechanisms involved in the drought response, GO enrichment analyses were conducted. Candidate genes with a putative function in the drought response were also identified. RESULTS A total of 52,599 gene models were obtained and after filtering on gene expression (FPKM ≥ 1), 35,733 gene models remained, of which 24,421 contained open reading frames. A total of 5,112 unique DEGs were identified between drought and WW conditions, of which the majority were found in the root tips. Phenotypically, genotype 592 displayed less growth reduction in response to drought compared to genotype 520. At the transcriptional level, genotype 520 displayed a greater response in the leaves as more DEGs were found in genotype 520 compared to genotype 592. In contrast, the transcriptional responses in the root tips were rather similar between the two genotypes. A core set of candidate genes encoding proteins with a putative function in drought response was identified, for example MYBs and bZIPs as well as chlorophyll a/b binding proteins. DISCUSSION We found substantial differences in drought responses between the genotypes, both at the phenotypic and transcriptional levels. In addition to the genotypic variation in several traits, we also found indications for genotypic variation in trait plasticity, which could play a role in drought adaptation. Furthermore, the two genotypes displayed overall similar transcriptional responses in the root tips, but more variation in the leaves. It is thus possible that the observed phenotypic differences could be a result of transcriptional differences mostly at the leaf level. CONCLUSIONS This study has contributed to a better general understanding of drought responses in woody plants, specifically in willows, and has implications for breeding research towards more drought adapted plants.
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Affiliation(s)
- Pascal Pucholt
- Department of Plant Biology, Uppsala BioCenter, Linnean Centre for Plant Biology, Swedish University of Agricultural Sciences, SE-750 07, Uppsala, Sweden.
| | - Per Sjödin
- Department of Plant Biology, Uppsala BioCenter, Linnean Centre for Plant Biology, Swedish University of Agricultural Sciences, SE-750 07, Uppsala, Sweden.
- Department of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, SE-752 36, Uppsala, Sweden.
| | - Martin Weih
- Department of Crop Production Ecology, Linnean Center for Plant Biology, Swedish University of Agricultural Sciences, SE-750 07, Uppsala, Sweden.
| | - Ann Christin Rönnberg-Wästljung
- Department of Plant Biology, Uppsala BioCenter, Linnean Centre for Plant Biology, Swedish University of Agricultural Sciences, SE-750 07, Uppsala, Sweden.
| | - Sofia Berlin
- Department of Plant Biology, Uppsala BioCenter, Linnean Centre for Plant Biology, Swedish University of Agricultural Sciences, SE-750 07, Uppsala, Sweden.
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Hanley SJ, Karp A. Genetic strategies for dissecting complex traits in biomass willows (Salix spp.). TREE PHYSIOLOGY 2014; 34:1167-80. [PMID: 24218244 DOI: 10.1093/treephys/tpt089] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Willows are highly diverse catkin-bearing trees and shrubs of the genus Salix. They occur in many growth forms, from tall trees to creeping alpines, and successfully occupy a wide variety of ecological niches. Shrubby willows (sub-genus Vetrix) have many characteristics that render them suited to cultivation in much faster growth cycles than conventional forestry. They respond well to coppicing, can be propagated vegetatively as cuttings and achieve rapid growth with low fertilizer inputs. As a result, willows grown as short rotation coppice are now among the leading commercially grown biomass crops in temperate regions. However, although willows have a long history of cultivation for traditional uses, their industrial use is relatively recent and, compared with major arable crops, they are largely undomesticated. Breeding programmes initiated to improve willow as a biomass crop achieved a doubling of yields within a period of <15 years. These advances were made by selecting for stem characteristics (height and diameter) and coppicing response (shoot number and shoot vigour), as well as resistance to pests, diseases and environmental stress, with little or no knowledge of the genetic basis of these traits. Genetics and genomics, combined with extensive phenotyping, have substantially improved our understanding of the basis of biomass traits in willow for more targeted breeding via marker-assisted selection. Here, we present the strategy we have adopted in which a genetic-based approach was used to dissect complex traits into more defined components for molecular breeding and gene discovery.
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Affiliation(s)
- Steven J Hanley
- Department of AgroEcology, Rothamsted Research, Cropping Carbon Institute Programme, Harpenden, Hertfordshire AL5 2JQ, UK
| | - Angela Karp
- Department of AgroEcology, Rothamsted Research, Cropping Carbon Institute Programme, Harpenden, Hertfordshire AL5 2JQ, UK
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Karp A, Hanley SJ, Trybush SO, Macalpine W, Pei M, Shield I. Genetic improvement of willow for bioenergy and biofuels. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2011; 53:151-65. [PMID: 21205181 DOI: 10.1111/j.1744-7909.2010.01015.x] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Willows (Salix spp.) are a very diverse group of catkin-bearing trees and shrubs that are widely distributed across temperate regions of the globe. Some species respond well to being grown in short rotation coppice (SRC) cycles, which are much shorter than conventional forestry. Coppicing reinvigorates growth and the biomass rapidly accumulated can be used as a source of renewable carbon for bioenergy and biofuels. As SRC willows re-distribute nutrients during the perennial cycle they require only minimal nitrogen fertilizer for growth. This results in fuel chains with potentially high greenhouse gas reductions. To exploit their potential for renewable energy, willows need to be kept free of pests and diseases and yields need to be improved without significantly increasing the requirements for fertilizers and water. The biomass composition needs to be optimized for different end-uses. Yields also need to be sustainable on land less productive for food crops to reduce conflicts over land use. Advances in understanding the physiology and growth of willow, and in the identification of genes underlying key traits, are now at the stage where they can start to be used in breeding programs to help achieve these goals.
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Affiliation(s)
- Angela Karp
- Centre for Bioenergy and Climate Change, Plant and Invertebrate Ecology Department, Rothamsted Research, Harpenden, Hertfordshire, AL5 2JQ, UK.
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