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Galeano E, Thomas BR. Unraveling genetic variation among white spruce families generated through different breeding strategies: Heritability, growth, physiology, hormones and gene expression. FRONTIERS IN PLANT SCIENCE 2023; 14:1052425. [PMID: 37077625 PMCID: PMC10106773 DOI: 10.3389/fpls.2023.1052425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Accepted: 03/15/2023] [Indexed: 05/03/2023]
Abstract
Tree improvement programs select genotypes for faster growth, at both early and late stages, to increase yields over unimproved material, and the improvement is frequently attributed to genetic control in growth parameters among genotypes. Underutilized genetic variability among genotypes also has the potential to ensure future gains are possible. However, the genetic variation in growth, physiology and hormone control among genotypes generated from different breeding strategies has not been well characterized in conifers. We assessed growth, biomass, gas exchange, gene expression and hormone levels in white spruce seedlings obtained from three different breeding strategies (controlled crosses, polymix pollination, open pollination) using parents grafted into a clonal seed orchard in Alberta, Canada. A pedigree-based best linear unbiased prediction (ABLUP) mixed model was implemented to quantify variability and narrow-sense heritability for target traits. The levels of several hormones and expression of gibberellin-related genes in apical internodes were also determined. Over the first two years of development, the estimated heritabilities for height, volume, total dry biomass, above ground dry biomass, root:shoot ratio and root length, varied between 0.10 and 0.21, with height having the highest value. The ABLUP values showed large genetic variability in growth and physiology traits both between families from different breeding strategies, and within families. The principal component analysis showed that developmental and hormonal traits explained 44.2% and 29.4% of the total phenotypic variation between the three different breeding strategies and two growth groups. In general, controlled crosses from the fast growth group showed the best apical growth, with more accumulation of indole-3-acetic acid, abscisic acid, phaseic acid, and a 4-fold greater gene expression of PgGA3ox1 in genotypes from controlled crosses versus those from open pollination. However, in some cases, open pollination from the fast and slow growth groups showed the best root development, higher water use efficiency (iWUE and δ13C) and more accumulation of zeatin and isopentenyladenosine. In conclusion, tree domestication can lead to trade-offs between growth, carbon allocation, photosynthesis, hormone levels and gene expression, and we encourage the use of this phenotypic variation identified in improved and unimproved trees to advance white spruce tree improvement programs.
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Affiliation(s)
- Esteban Galeano
- Department of Forestry, Mississippi State University, Starkville, MS, United States
- Department of Renewable Resources, University of Alberta, Edmonton, AB, Canada
- *Correspondence: Esteban Galeano,
| | - Barb R. Thomas
- Department of Renewable Resources, University of Alberta, Edmonton, AB, Canada
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Gagalova KK, Warren RL, Coombe L, Wong J, Nip KM, Yuen MMS, Whitehill JGA, Celedon JM, Ritland C, Taylor GA, Cheng D, Plettner P, Hammond SA, Mohamadi H, Zhao Y, Moore RA, Mungall AJ, Boyle B, Laroche J, Cottrell J, Mackay JJ, Lamothe M, Gérardi S, Isabel N, Pavy N, Jones SJM, Bohlmann J, Bousquet J, Birol I. Spruce giga-genomes: structurally similar yet distinctive with differentially expanding gene families and rapidly evolving genes. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2022; 111:1469-1485. [PMID: 35789009 DOI: 10.1111/tpj.15889] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 06/22/2022] [Accepted: 06/27/2022] [Indexed: 06/15/2023]
Abstract
Spruces (Picea spp.) are coniferous trees widespread in boreal and mountainous forests of the northern hemisphere, with large economic significance and enormous contributions to global carbon sequestration. Spruces harbor very large genomes with high repetitiveness, hampering their comparative analysis. Here, we present and compare the genomes of four different North American spruces: the genome assemblies for Engelmann spruce (Picea engelmannii) and Sitka spruce (Picea sitchensis) together with improved and more contiguous genome assemblies for white spruce (Picea glauca) and for a naturally occurring introgress of these three species known as interior spruce (P. engelmannii × glauca × sitchensis). The genomes were structurally similar, and a large part of scaffolds could be anchored to a genetic map. The composition of the interior spruce genome indicated asymmetric contributions from the three ancestral genomes. Phylogenetic analysis of the nuclear and organelle genomes revealed a topology indicative of ancient reticulation. Different patterns of expansion of gene families among genomes were observed and related with presumed diversifying ecological adaptations. We identified rapidly evolving genes that harbored high rates of non-synonymous polymorphisms relative to synonymous ones, indicative of positive selection and its hitchhiking effects. These gene sets were mostly distinct between the genomes of ecologically contrasted species, and signatures of convergent balancing selection were detected. Stress and stimulus response was identified as the most frequent function assigned to expanding gene families and rapidly evolving genes. These two aspects of genomic evolution were complementary in their contribution to divergent evolution of presumed adaptive nature. These more contiguous spruce giga-genome sequences should strengthen our understanding of conifer genome structure and evolution, as their comparison offers clues into the genetic basis of adaptation and ecology of conifers at the genomic level. They will also provide tools to better monitor natural genetic diversity and improve the management of conifer forests. The genomes of four closely related North American spruces indicate that their high similarity at the morphological level is paralleled by the high conservation of their physical genome structure. Yet, the evidence of divergent evolution is apparent in their rapidly evolving genomes, supported by differential expansion of key gene families and large sets of genes under positive selection, largely in relation to stimulus and environmental stress response.
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Affiliation(s)
- Kristina K Gagalova
- Canada's Michael Smith Genome Sciences Centre, Vancouver, BC, V5Z 4S6, Canada
| | - René L Warren
- Canada's Michael Smith Genome Sciences Centre, Vancouver, BC, V5Z 4S6, Canada
| | - Lauren Coombe
- Canada's Michael Smith Genome Sciences Centre, Vancouver, BC, V5Z 4S6, Canada
| | - Johnathan Wong
- Canada's Michael Smith Genome Sciences Centre, Vancouver, BC, V5Z 4S6, Canada
| | - Ka Ming Nip
- Canada's Michael Smith Genome Sciences Centre, Vancouver, BC, V5Z 4S6, Canada
| | - Macaire Man Saint Yuen
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Justin G A Whitehill
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Jose M Celedon
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Carol Ritland
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Greg A Taylor
- Canada's Michael Smith Genome Sciences Centre, Vancouver, BC, V5Z 4S6, Canada
| | - Dean Cheng
- Canada's Michael Smith Genome Sciences Centre, Vancouver, BC, V5Z 4S6, Canada
| | - Patrick Plettner
- Canada's Michael Smith Genome Sciences Centre, Vancouver, BC, V5Z 4S6, Canada
| | - S Austin Hammond
- Canada's Michael Smith Genome Sciences Centre, Vancouver, BC, V5Z 4S6, Canada
- Next-Generation Sequencing Facility, University of Saskatchewan, Saskatoon, SK, S7N 5E5, Canada
| | - Hamid Mohamadi
- Canada's Michael Smith Genome Sciences Centre, Vancouver, BC, V5Z 4S6, Canada
| | - Yongjun Zhao
- Canada's Michael Smith Genome Sciences Centre, Vancouver, BC, V5Z 4S6, Canada
| | - Richard A Moore
- Canada's Michael Smith Genome Sciences Centre, Vancouver, BC, V5Z 4S6, Canada
| | - Andrew J Mungall
- Canada's Michael Smith Genome Sciences Centre, Vancouver, BC, V5Z 4S6, Canada
| | - Brian Boyle
- Institute for Systems and Integrative Biology, Université Laval, Québec, QC, GIV 0A6, Canada
| | - Jérôme Laroche
- Institute for Systems and Integrative Biology, Université Laval, Québec, QC, GIV 0A6, Canada
| | - Joan Cottrell
- Forest Research, U.K. Forestry Commission, Northern Research Station, Roslin, EH25 9SY, Midlothian, UK
| | - John J Mackay
- Department of Plant Sciences, University of Oxford, Oxford, OX1 3RB, UK
| | - Manuel Lamothe
- Natural Resources Canada, Canadian Forest Service, Laurentian Forestry Centre, Québec, QC, G1V 4C7, Canada
| | - Sébastien Gérardi
- Institute for Systems and Integrative Biology, Université Laval, Québec, QC, GIV 0A6, Canada
- Canada Research Chair in Forest Genomics, Forest Research Centre, Université Laval, Québec, QC, G1V 0A6, Canada
| | - Nathalie Isabel
- Natural Resources Canada, Canadian Forest Service, Laurentian Forestry Centre, Québec, QC, G1V 4C7, Canada
- Canada Research Chair in Forest Genomics, Forest Research Centre, Université Laval, Québec, QC, G1V 0A6, Canada
| | - Nathalie Pavy
- Institute for Systems and Integrative Biology, Université Laval, Québec, QC, GIV 0A6, Canada
- Canada Research Chair in Forest Genomics, Forest Research Centre, Université Laval, Québec, QC, G1V 0A6, Canada
| | - Steven J M Jones
- Canada's Michael Smith Genome Sciences Centre, Vancouver, BC, V5Z 4S6, Canada
| | - Joerg Bohlmann
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Jean Bousquet
- Institute for Systems and Integrative Biology, Université Laval, Québec, QC, GIV 0A6, Canada
- Canada Research Chair in Forest Genomics, Forest Research Centre, Université Laval, Québec, QC, G1V 0A6, Canada
| | - Inanc Birol
- Canada's Michael Smith Genome Sciences Centre, Vancouver, BC, V5Z 4S6, Canada
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Geras'kin S, Volkova P, Vasiliyev D, Dikareva N, Oudalova A, Kazakova E, Makarenko E, Duarte G, Kuzmenkov A. Scots pine as a promising indicator organism for biomonitoring of the polluted environment: A case study on chronically irradiated populations. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2019; 842:3-13. [PMID: 31255224 DOI: 10.1016/j.mrgentox.2018.12.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Revised: 12/18/2018] [Accepted: 12/20/2018] [Indexed: 01/13/2023]
Abstract
In this paper the main results of long-term (2003-2016) observations on Scots pine populations inhabiting sites affected by the Chernobyl accident are presented. Populations growing for many years under chronic radiation exposure are characterized by the enhanced mutation rates, increased genetic diversity, changes in the gene expression and in the level of genome-wide methylation, alterations in the temporal dynamics of cytogenetic abnormalities and genetic structure of populations. However, significant changes at the genetic level had no effects on enzymatic activity, morphological abnormalities, and reproductive ability of pine trees. The results presented increase our understanding of the long-term effects of chronic radiation exposure on plant populations in the wild nature and provide important information for the management and monitoring of radioactively contaminated territories.
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Affiliation(s)
| | - Polina Volkova
- Russian Institute of Radiology and Agroecology, Obninsk, Russia
| | - Denis Vasiliyev
- Russian Institute of Radiology and Agroecology, Obninsk, Russia
| | - Nina Dikareva
- Russian Institute of Radiology and Agroecology, Obninsk, Russia
| | - Alla Oudalova
- Russian Institute of Radiology and Agroecology, Obninsk, Russia; Obninsk Institute for Nuclear Power Engineering, National Research Nuclear University MEPhI, Obninsk, Russia
| | | | | | - Gustavo Duarte
- Russian Institute of Radiology and Agroecology, Obninsk, Russia; Institute Jean-Pierre Bourgin, Versailles, France
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Zaidem ML, Groen SC, Purugganan MD. Evolutionary and ecological functional genomics, from lab to the wild. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2019; 97:40-55. [PMID: 30444573 DOI: 10.1111/tpj.14167] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 11/10/2018] [Accepted: 11/13/2018] [Indexed: 05/12/2023]
Abstract
Plant phenotypes are the result of both genetic and environmental forces that act to modulate trait expression. Over the last few years, numerous approaches in functional genomics and systems biology have led to a greater understanding of plant phenotypic variation and plant responses to the environment. These approaches, and the questions that they can address, have been loosely termed evolutionary and ecological functional genomics (EEFG), and have been providing key insights on how plants adapt and evolve. In particular, by bringing these studies from the laboratory to the field, EEFG studies allow us to gain greater knowledge of how plants function in their natural contexts.
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Affiliation(s)
- Maricris L Zaidem
- Department of Biology, Center for Genomics and Systems Biology, New York University, 12 Waverly Place, New York, NY, 10003, USA
| | - Simon C Groen
- Department of Biology, Center for Genomics and Systems Biology, New York University, 12 Waverly Place, New York, NY, 10003, USA
| | - Michael D Purugganan
- Department of Biology, Center for Genomics and Systems Biology, New York University, 12 Waverly Place, New York, NY, 10003, USA
- Center for Genomics and Systems Biology, NYU Abu Dhabi Research Institute, New York University Abu Dhabi, Saadiyat Island, Abu Dhabi, United Arab Emirates
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Alakärppä E, Salo HM, Valledor L, Cañal MJ, Häggman H, Vuosku J. Natural variation of DNA methylation and gene expression may determine local adaptations of Scots pine populations. JOURNAL OF EXPERIMENTAL BOTANY 2018; 69:5293-5305. [PMID: 30113688 DOI: 10.1093/jxb/ery292] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Accepted: 08/01/2018] [Indexed: 05/27/2023]
Abstract
Long-lived conifers are vulnerable to climate change because classical evolutionary processes are slow in developing adaptive responses. Therefore, the capacity of a genotype to adopt different phenotypes is important. Gene expression is the primary mechanism that converts genome-encoded information into phenotypes, and DNA methylation is employed in the epigenetic regulation of gene expression. We investigated variations in global DNA methylation and gene expression between three Scots pine (Pinus sylvestris L.) populations located in northern and southern Finland using mature seeds. Gene expression levels were studied in six DNA methyltransferase (DNMT) genes, which were characterized in this study, and in 19 circadian clock genes regulating adaptive traits. In embryos, expression diversity was found for three DNMT genes, which maintain DNA methylation. The expression of two DNMT genes was strongly correlated with climate variables, which suggests a role for DNA methylation in local adaptation. For adaptation-related genes, expression levels showed between-population variation in 11 genes in megagametophytes and in eight genes in embryos, and many of these genes were linked to climate factors. Altogether, our results suggest that differential DNA methylation and gene expression contribute to local adaptation in Scots pine populations and may enhance the fitness of trees under rapidly changing climatic conditions.
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Affiliation(s)
- Emmi Alakärppä
- Department of Ecology and Genetics, University of Oulu, Oulu, Finland
| | - Heikki M Salo
- Department of Ecology and Genetics, University of Oulu, Oulu, Finland
| | - Luis Valledor
- Plant Physiology, Faculty of Biology, University of Oviedo, Oviedo, Spain
| | - Maria Jesús Cañal
- Plant Physiology, Faculty of Biology, University of Oviedo, Oviedo, Spain
| | - Hely Häggman
- Department of Ecology and Genetics, University of Oulu, Oulu, Finland
| | - Jaana Vuosku
- Department of Ecology and Genetics, University of Oulu, Oulu, Finland
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Volkova PY, Geras’kin SA, Kazakova EA. Radiation exposure in the remote period after the Chernobyl accident caused oxidative stress and genetic effects in Scots pine populations. Sci Rep 2017; 7:43009. [PMID: 28223696 PMCID: PMC5320440 DOI: 10.1038/srep43009] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Accepted: 01/18/2017] [Indexed: 11/10/2022] Open
Abstract
Even 30 years after the Chernobyl accident, biological effects of irradiation are observed in the chronically exposed Scots pine populations. Chronic radiation exposure at dose rates above 50 mGy∙yr-1 caused oxidative stress and led to the increase of antioxidants concentrations in these populations. Genetic variability was examined for 6 enzymes and 14 enzymatic loci of 6 Scots pine populations. Dose rates over 10 mGy∙yr-1 caused the increased frequency of mutations and changes in genetic structure of Scots pine populations. However, the same dose rates had no effect on enzymatic activities. The results indicate that even relatively low dose rates of radiation can be considered as an ecological factor which should be taken into account for ecological management and radiation protection of biota species.
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Verta JP, Landry CR, MacKay J. Dissection of expression-quantitative trait locus and allele specificity using a haploid/diploid plant system - insights into compensatory evolution of transcriptional regulation within populations. THE NEW PHYTOLOGIST 2016; 211:159-171. [PMID: 26891783 DOI: 10.1111/nph.13888] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Accepted: 01/06/2016] [Indexed: 06/05/2023]
Abstract
Regulation of gene expression plays a central role in translating genotypic variation into phenotypic variation. Dissection of the genetic basis of expression variation is key to understanding how expression regulation evolves. Such analyses remain challenging in contexts where organisms are outbreeding, highly heterozygous and long-lived such as in the case of conifer trees. We developed an RNA sequencing (RNA-seq)-based approach for both expression-quantitative trait locus (eQTL) mapping and the detection of cis-acting (allele-specific) vs trans-acting (non-allele-specific) eQTLs. This method can be potentially applied to many conifers. We used haploid and diploid meiotic seed tissues of a single self-fertilized white spruce (Picea glauca) individual to dissect eQTLs according to linkage and allele specificity. The genetic architecture of local eQTLs linked to the expressed genes was particularly complex, consisting of cis-acting, trans-acting and, surprisingly, compensatory cis-trans effects. These compensatory effects influence expression in opposite directions and are neutral when combined in homozygotes. Nearly half of local eQTLs were under compensation, indicating that close linkage between compensatory cis-trans factors is common in spruce. Compensated genes were overrepresented in developmental and cell organization functions. Our haploid-diploid eQTL analysis in spruce revealed that compensatory cis-trans eQTLs segregate within populations and evolve in close genetic linkage.
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Affiliation(s)
- Jukka-Pekka Verta
- Centre d'étude de la forêt, Département des sciences du bois et de la forêt, Université Laval, Québec, QC, Canada G1V 0A6
- Institut de Biologie Intégrative et des Systèmes, Université Laval, Québec, QC, Canada G1V 0A6
| | - Christian R Landry
- Institut de Biologie Intégrative et des Systèmes, Université Laval, Québec, QC, Canada G1V 0A6
- Département de Biologie, Université Laval, Québec, QC, Canada G1V 0A6
| | - John MacKay
- Centre d'étude de la forêt, Département des sciences du bois et de la forêt, Université Laval, Québec, QC, Canada G1V 0A6
- Institut de Biologie Intégrative et des Systèmes, Université Laval, Québec, QC, Canada G1V 0A6
- Department of Plant Sciences, University of Oxford, Oxford, OX1 3RB, UK
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Prunier J, Verta JP, MacKay JJ. Conifer genomics and adaptation: at the crossroads of genetic diversity and genome function. THE NEW PHYTOLOGIST 2016; 209:44-62. [PMID: 26206592 DOI: 10.1111/nph.13565] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Accepted: 06/14/2015] [Indexed: 05/21/2023]
Abstract
Conifers have been understudied at the genomic level despite their worldwide ecological and economic importance but the situation is rapidly changing with the development of next generation sequencing (NGS) technologies. With NGS, genomics research has simultaneously gained in speed, magnitude and scope. In just a few years, genomes of 20-24 gigabases have been sequenced for several conifers, with several others expected in the near future. Biological insights have resulted from recent sequencing initiatives as well as genetic mapping, gene expression profiling and gene discovery research over nearly two decades. We review the knowledge arising from conifer genomics research emphasizing genome evolution and the genomic basis of adaptation, and outline emerging questions and knowledge gaps. We discuss future directions in three areas with potential inputs from NGS technologies: the evolutionary impacts of adaptation in conifers based on the adaptation-by-speciation model; the contributions of genetic variability of gene expression in adaptation; and the development of a broader understanding of genetic diversity and its impacts on genome function. These research directions promise to sustain research aimed at addressing the emerging challenges of adaptation that face conifer trees.
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Affiliation(s)
- Julien Prunier
- Centre for Forest Research and Institute for Systems and Integrative Biology, Université Laval, Quebec, QC, G1V 0A6, Canada
| | - Jukka-Pekka Verta
- Friedrich Miescher Laboratory of the Max Planck Society, Spemannstrasse 39, Tübingen, 72076, Germany
| | - John J MacKay
- Centre for Forest Research and Institute for Systems and Integrative Biology, Université Laval, Quebec, QC, G1V 0A6, Canada
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Liu Y, Müller K, El-Kassaby YA, Kermode AR. Changes in hormone flux and signaling in white spruce (Picea glauca) seeds during the transition from dormancy to germination in response to temperature cues. BMC PLANT BIOLOGY 2015; 15:292. [PMID: 26680643 PMCID: PMC4683703 DOI: 10.1186/s12870-015-0638-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 10/05/2015] [Indexed: 05/21/2023]
Abstract
BACKGROUND Seeds use environmental cues such as temperature to coordinate the timing of their germination, allowing plants to synchronize their life history with the seasons. Winter chilling is of central importance to alleviate seed dormancy, but very little is known of how chilling responses are regulated in conifer seeds. White spruce (Picea glauca) is an important conifer species of boreal forests in the North American taiga. The recent sequencing and assembly of the white spruce genome allows for comparative gene expression studies toward elucidating the molecular mechanisms governing dormancy alleviation by moist chilling. Here we focused on hormone metabolite profiling and analyses of genes encoding components of hormone signal transduction pathways, to elucidate changes during dormancy alleviation and to help address how germination cues such as temperature and light trigger radicle emergence. RESULTS ABA, GA, and auxin underwent considerable changes as seeds underwent moist chilling and during subsequent germination; likewise, transcripts encoding hormone-signaling components (e.g. ABI3, ARF4 and Aux/IAA) were differentially regulated during these critical stages. During moist chilling, active IAA was maintained at constant levels, but IAA conjugates (IAA-Asp and IAA-Glu) were substantially accumulated. ABA concentrations decreased during germination of previously moist-chilled seeds, while the precursor of bioactive GA1 (GA53) accumulated. We contend that seed dormancy and germination may be partly mediated through the changing hormone concentrations and a modulation of interactions between central auxin-signaling pathway components (TIR1/AFB, Aux/IAA and ARF4). In response to germination cues, namely exposure to light and to increased temperature: the transfer of seeds from moist-chilling to 30 °C, significant changes in gene transcripts and protein expression occurred during the first six hours, substantiating a very swift reaction to germination-promoting conditions after seeds had received sufficient exposure to the chilling stimulus. CONCLUSIONS The dormancy to germination transition in white spruce seeds was correlated with changes in auxin conjugation, auxin signaling components, and potential interactions between auxin-ABA signaling cascades (e.g. the transcription factor ARF4 and ABI3). Auxin flux adds a new dimension to the ABA:GA balance mechanism that underlies both dormancy alleviation by chilling, and subsequent radicle emergence to complete germination by warm temperature and light stimuli.
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Affiliation(s)
- Yang Liu
- Department of Forest and Conservation Sciences, Faculty of Forestry, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada.
| | - Kerstin Müller
- Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, V5A 1S6, Canada.
| | - Yousry A El-Kassaby
- Department of Forest and Conservation Sciences, Faculty of Forestry, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada.
| | - Allison R Kermode
- Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, V5A 1S6, Canada.
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10
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Conservation genetics of Magnolia acuminata, an endangered species in Canada: Can genetic diversity be maintained in fragmented, peripheral populations? CONSERV GENET 2015. [DOI: 10.1007/s10592-015-0746-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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11
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De La Torre AR, Lin YC, Van de Peer Y, Ingvarsson PK. Genome-wide analysis reveals diverged patterns of codon bias, gene expression, and rates of sequence evolution in picea gene families. Genome Biol Evol 2015; 7:1002-15. [PMID: 25747252 PMCID: PMC4419791 DOI: 10.1093/gbe/evv044] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The recent sequencing of several gymnosperm genomes has greatly facilitated studying the evolution of their genes and gene families. In this study, we examine the evidence for expression-mediated selection in the first two fully sequenced representatives of the gymnosperm plant clade (Picea abies and Picea glauca). We use genome-wide estimates of gene expression (>50,000 expressed genes) to study the relationship between gene expression, codon bias, rates of sequence divergence, protein length, and gene duplication. We found that gene expression is correlated with rates of sequence divergence and codon bias, suggesting that natural selection is acting on Picea protein-coding genes for translational efficiency. Gene expression, rates of sequence divergence, and codon bias are correlated with the size of gene families, with large multicopy gene families having, on average, a lower expression level and breadth, lower codon bias, and higher rates of sequence divergence than single-copy gene families. Tissue-specific patterns of gene expression were more common in large gene families with large gene expression divergence than in single-copy families. Recent family expansions combined with large gene expression variation in paralogs and increased rates of sequence evolution suggest that some Picea gene families are rapidly evolving to cope with biotic and abiotic stress. Our study highlights the importance of gene expression and natural selection in shaping the evolution of protein-coding genes in Picea species, and sets the ground for further studies investigating the evolution of individual gene families in gymnosperms.
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Affiliation(s)
| | - Yao-Cheng Lin
- Department of Plant Systems Biology, VIB, and Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium
| | - Yves Van de Peer
- Department of Plant Systems Biology, VIB, and Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium Genomics Research Institute, University of Pretoria, South Africa
| | - Pär K Ingvarsson
- Department of Ecology and Environmental Science, Umeå University, Sweden Umeå Plant Science Centre, Umeå, Sweden
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Geras'kin SA, Volkova PY. Genetic diversity in Scots pine populations along a radiation exposure gradient. THE SCIENCE OF THE TOTAL ENVIRONMENT 2014; 496:317-327. [PMID: 25087063 DOI: 10.1016/j.scitotenv.2014.07.020] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Revised: 07/05/2014] [Accepted: 07/05/2014] [Indexed: 06/03/2023]
Abstract
Polymorphisms of antioxidant enzymes were studied in the endosperm and embryos of seeds from Scots pine populations inhabiting sites in the Bryansk region of Russia radioactively contaminated as a result of the Chernobyl accident. Chronic radiation exposure at dose rates from 0.8 μGy/h led to a significant increase in the rate of enzymatic loci mutations. The main parameters of genetic variability of the affected Scots pine populations had considerably higher values than those from the reference site. Changes in the genetic makeup of Scots pine populations were observed at dose rates greater than 10.4 μGy/h. However, the higher mutation rate had no effect on the activities of antioxidant enzymes.
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Affiliation(s)
- Stanislav A Geras'kin
- Russian Institute of Agricultural Radiology and Agroecology, Kievskoe shosse, 109km, 249032 Obninsk, Russia.
| | - Polina Yu Volkova
- Russian Institute of Agricultural Radiology and Agroecology, Kievskoe shosse, 109km, 249032 Obninsk, Russia
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Renaut S. A new approach to quantify the adaptive potential of gene expression variation in gymnosperms. Mol Ecol 2013; 22:2361-3. [PMID: 23738368 DOI: 10.1111/mec.12303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Variation in patterns of gene expression contributes to phenotypic diversity and can ultimately predict adaptive responses. However, in many cases, the consequences of regulatory mutations on patterns of gene expression and ultimately phenotypic differences remain elusive. A standard way to study the genetic architecture of expression variation in model systems has been to map gene expression variation to genetic loci (Fig. 1a). At the same time, in many nonmodel species, especially for long-lived organisms, controlled crosses are not feasible. If we are to expand our understanding of the role of regulatory mutations on phenotypes, we need to develop new methodologies to study species under ecologically relevant conditions. In this issue of Molecular Ecology, Verta et al. (2013) present a new approach to analyse gene expression variation and regulatory networks in gymnosperms (Fig. 1b). They capitalized on the fact that gymnosperm seeds contain an energy storage tissue (the megagametophyte) that is directly derived from a single haploid cell (the megaspore). The authors identified over 800 genes for which expression segregated in this maternally inherited haploid tissue. Based on the observed segregation patterns, these genes (Mendelian Expression Traits) are most probably controlled by biallelic variants at a single locus. Most of these genes also belonged to different regulatory networks, except for one large group of 180 genes under the control of a putative trans-acting factor. In addition, the approach developed here may also help to uncover the effect of rare recessive mutations, which usually remain hidden in a heterozygous state in diploid individuals. The appeal of the work by Verta et al. (2013) to study gene expression variation is in its simplicity, which circumvents several of the hurdles behind traditional expression quantitative trait locus (eQTL) studies, and could potentially be applied to a large number of species.
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Affiliation(s)
- Sébastien Renaut
- Biodiversity Research Centre and Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada.
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