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Pabuayon ICM, Kitazumi A, Gregorio GB, Singh RK, de los Reyes BG. Contributions of Adaptive Plant Architecture to Transgressive Salinity Tolerance in Recombinant Inbred Lines of Rice: Molecular Mechanisms Based on Transcriptional Networks. Front Genet 2020; 11:594569. [PMID: 33193743 PMCID: PMC7644915 DOI: 10.3389/fgene.2020.594569] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Accepted: 10/05/2020] [Indexed: 11/30/2022] Open
Abstract
Genetic novelties are important nucleators of adaptive speciation. Transgressive segregation is a major mechanism that creates genetic novelties with morphological and developmental attributes that confer adaptive advantages in certain environments. This study examined the morpho-developmental and physiological profiles of recombinant inbred lines (RILs) from the salt-sensitive IR29 and salt-tolerant Pokkali rice, representing the total range of salt tolerance including the outliers at both ends of the spectrum. Morpho-developmental and physiological profiles were integrated with a hypothesis-driven interrogation of mRNA and miRNA transcriptomes to uncover the critical genetic networks that have been rewired for novel adaptive architecture. The transgressive super-tolerant FL510 had a characteristic small tiller angle and wider, more erect, sturdier, and darker green leaves. This unique morphology resulted in lower transpiration rate, which also conferred a special ability to retain water more efficiently for osmotic avoidance. The unique ability for water retention conferred by such adaptive morphology appeared to enhance the efficacy of defenses mediated by Na+ exclusion mechanism (SalTol-effects) inherited from Pokkali. The super-tolerant FL510 and super-sensitive FL499 had the smallest proportions of differentially expressed genes with little overlaps. Genes that were steadily upregulated in FL510 comprised a putative cytokinin-regulated genetic network that appeared to maintain robust growth under salt stress through well-orchestrated cell wall biogenesis and cell expansion, likely through major regulatory (OsRR23, OsHK5) and biosynthetic (OsIPT9) genes in the cytokinin signaling pathway. Meanwhile, a constitutively expressed cluster in FL510 prominently featured two transcription factors (OsIBH1, TAC3) that control tiller angle and growth habit through the brassinosteroid signaling pathway. Both the putative cytokinin-mediated and brassinosteroid-mediated clusters appeared to function as highly coordinated network synergies in FL510. In contrast, both networks appeared to be sub-optimal and inferior in the other RILs and parents as they were disjointed and highly fragmented. Transgressively expressed miRNAs (miR169, miR397, miR827) were also identified as prominent signatures of FL510, with functional implications to mechanisms that support robust growth, homeostasis, and osmotic stress avoidance. Results of this study demonstrate how genetic recombination creates novel morphology that complements inducible defenses hence transgressive adaptive phenotypes.
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Affiliation(s)
| | - Ai Kitazumi
- Department of Plant and Soil Science, Texas Tech University, Lubbock, TX, United States
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Pre-symptomatic modified phytohormone profile is associated with lower phytoplasma titres in an Arabidopsis seor1ko line. Sci Rep 2020; 10:14770. [PMID: 32901060 PMCID: PMC7479616 DOI: 10.1038/s41598-020-71660-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 08/17/2020] [Indexed: 11/16/2022] Open
Abstract
The proteins AtSEOR1 and AtSEOR2 occur as conjugates in the form of filaments in sieve elements of Arabidopsis thaliana. A reduced phytoplasma titre found in infected defective-mutant Atseor1ko plants in previous work raised the speculation that non-conjugated SEOR2 is involved in the phytohormone-mediated suppression of Chrysanthemum Yellows (CY)-phytoplasma infection transmitted by Euscelidius variegatus (Ev). This early and long-lasting SEOR2 impact was revealed in Atseor1ko plants by the lack of detectable phytoplasmas at an early stage of infection (symptomless plants) and a lower phytoplasma titre at a later stage (fully symptomatic plants). The high insect survival rate on Atseor1ko line and the proof of phytoplasma infection at the end of the acquisition access period confirmed the high transmission efficiency of CY-phytoplasma by the vectors. Transmission electron microscopy analysis ruled out a direct role of SE filament proteins in physical phytoplasma containment. Time-correlated HPLC–MS/MS-based phytohormone analyses revealed increased jasmonate levels in midribs of Atseor1ko plants at an early stage of infection and appreciably enhanced levels of indole acetic acid and abscisic acid at the early and late stages. Effects of Ev-probing on phytohormone levels was not found. The results suggest that SEOR2 interferes with phytohormonal pathways in Arabidopsis midrib tissues in order to establish early defensive responses to phytoplasma infection.
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The Role of Triacylglycerol in Plant Stress Response. PLANTS 2020; 9:plants9040472. [PMID: 32276473 PMCID: PMC7238164 DOI: 10.3390/plants9040472] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 03/31/2020] [Accepted: 04/02/2020] [Indexed: 12/12/2022]
Abstract
Vegetable oil is mainly composed of triacylglycerol (TAG), a storage lipid that serves as a major commodity for food and industrial purposes, as well as an alternative biofuel source. While TAG is typically not produced at significant levels in vegetative tissues, emerging evidence suggests that its accumulation in such tissues may provide one mechanism by which plants cope with abiotic stress. Different types of abiotic stress induce lipid remodeling through the action of specific lipases, which results in various alterations in membrane lipid composition. This response induces the formation of toxic lipid intermediates that cause membrane damage or cell death. However, increased levels of TAG under stress conditions are believed to function, at least in part, as a means of sequestering these toxic lipid intermediates. Moreover, the lipid droplets (LDs) in which TAG is enclosed also function as a subcellular factory to provide binding sites and substrates for the biosynthesis of bioactive compounds that protect against insects and fungi. Though our knowledge concerning the role of TAG in stress tolerance is expanding, many gaps in our understanding of the mechanisms driving these processes are still evident. In this review, we highlight progress that has been made to decipher the role of TAG in plant stress response, and we discuss possible ways in which this information could be utilized to improve crops in the future.
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Walter GM, Abbott RJ, Brennan AC, Bridle JR, Chapman M, Clark J, Filatov D, Nevado B, Ortiz-Barrientos D, Hiscock SJ. Senecio as a model system for integrating studies of genotype, phenotype and fitness. THE NEW PHYTOLOGIST 2020; 226:326-344. [PMID: 31951018 DOI: 10.1111/nph.16434] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Accepted: 12/17/2019] [Indexed: 05/24/2023]
Abstract
Two major developments have made it possible to use examples of ecological radiations as model systems to understand evolution and ecology. First, the integration of quantitative genetics with ecological experiments allows detailed connections to be made between genotype, phenotype, and fitness in the field. Second, dramatic advances in molecular genetics have created new possibilities for integrating field and laboratory experiments with detailed genetic sequencing. Combining these approaches allows evolutionary biologists to better study the interplay between genotype, phenotype, and fitness to explore a wide range of evolutionary processes. Here, we present the genus Senecio (Asteraceae) as an excellent system to integrate these developments, and to address fundamental questions in ecology and evolution. Senecio is one of the largest and most phenotypically diverse genera of flowering plants, containing species ranging from woody perennials to herbaceous annuals. These Senecio species exhibit many growth habits, life histories, and morphologies, and they occupy a multitude of environments. Common within the genus are species that have hybridized naturally, undergone polyploidization, and colonized diverse environments, often through rapid phenotypic divergence and adaptive radiation. These diverse experimental attributes make Senecio an attractive model system in which to address a broad range of questions in evolution and ecology.
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Affiliation(s)
- Greg M Walter
- School of Biological Sciences, University of Bristol, Bristol, BS8 1TQ, UK
| | - Richard J Abbott
- School of Biology, University of St Andrews, St Andrews, Fife, KY16 9TH, UK
| | - Adrian C Brennan
- School of Biological and Biomedical Sciences, University of Durham, Durham, DH1 3LE, UK
| | - Jon R Bridle
- School of Biological Sciences, University of Bristol, Bristol, BS8 1TQ, UK
| | - Mark Chapman
- School of Biological Sciences, University of Southampton, Southampton, SO17 1BJ, UK
| | - James Clark
- Department of Plant Sciences, University of Oxford, Oxford, OX1 3RB, UK
| | - Dmitry Filatov
- Department of Plant Sciences, University of Oxford, Oxford, OX1 3RB, UK
| | - Bruno Nevado
- Department of Plant Sciences, University of Oxford, Oxford, OX1 3RB, UK
| | | | - Simon J Hiscock
- Department of Plant Sciences, University of Oxford, Oxford, OX1 3RB, UK
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Cai ZQ, Gao Q. Comparative physiological and biochemical mechanisms of salt tolerance in five contrasting highland quinoa cultivars. BMC PLANT BIOLOGY 2020; 20:70. [PMID: 32050903 PMCID: PMC7017487 DOI: 10.1186/s12870-020-2279-8] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2019] [Accepted: 02/05/2020] [Indexed: 05/05/2023]
Abstract
BACKGROUND Chenopodium quinoa Willd., a halophytic crop, shows great variability among different genotypes in response to salt. To investigate the salinity tolerance mechanisms, five contrasting quinoa cultivars belonging to highland ecotype were compared for their seed germination (under 0, 100 and 400 mM NaCl) and seedling's responses under five salinity levels (0, 100, 200, 300 and 400 mM NaCl). RESULTS Substantial variations were found in plant size (biomass) and overall salinity tolerance (plant biomass in salt treatment as % of control) among the different quinoa cultivars. Plant salinity tolerance was negatively associated with plant size, especially at lower salinity levels (< 300 mM NaCl), but salt tolerance between seed germination and seedling growth was not closely correlated. Except for shoot/root ratio, all measured plant traits responded to salt in a genotype-specific way. Salt stress resulted in decreased plant height, leaf area, root length, and root/shoot ratio in each cultivar. With increasing salinity levels, leaf superoxide dismutase (SOD) activity and lipid peroxidation generally increased, but catalase (CAT) and peroxidase (POD) activities showed non-linear patterns. Organic solutes (soluble sugar, proline and protein) accumulated in leaves, whereas inorganic ion (Na+ and K+) increased but K+/Na+ decreased in both leaves and roots. Across different salinity levels and cultivars, without close relationships with antioxidant enzyme activities (SOD, POD, or CAT), salinity tolerance was significantly negatively correlated with organic solute and malondialdehyde contents in leaves and inorganic ion contents in leaves or roots (except for root K+ content), but positively correlated with K+/Na+ ratio in leaves or roots. CONCLUSION Our results indicate that leaf osmoregulation, K+ retention, Na+ exclusion, and ion homeostasis are the main physiological mechanisms conferring salinity tolerance of these cultivars, rather than the regulations of leaf antioxidative ability. As an index of salinity tolerance, K+/Na+ ratio in leaves or roots can be used for the selective breeding of highland quinoa cultivars.
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Affiliation(s)
- Zhi-Quan Cai
- Department of Horticulture, Foshan University, Foshan, 528000, China.
- CAS Key Laboratory of Tropical Plant Resources and Sustainable Use, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, 666303, China.
| | - Qi Gao
- CAS Key Laboratory of Tropical Plant Resources and Sustainable Use, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, 666303, China.
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Sanderson BJ, Park S, Jameel MI, Kraft JC, Thomashow MF, Schemske DW, Oakley CG. Genetic and physiological mechanisms of freezing tolerance in locally adapted populations of a winter annual. AMERICAN JOURNAL OF BOTANY 2020; 107:250-261. [PMID: 31762012 PMCID: PMC7065183 DOI: 10.1002/ajb2.1385] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Accepted: 08/14/2019] [Indexed: 05/22/2023]
Abstract
PREMISE Despite myriad examples of local adaptation, the phenotypes and genetic variants underlying such adaptive differentiation are seldom known. Recent work on freezing tolerance and local adaptation in ecotypes of Arabidopsis thaliana from Italy and Sweden provides an essential foundation for uncovering the genotype-phenotype-fitness map for an adaptive response to a key environmental stress. METHODS We examined the consequences of a naturally occurring loss-of-function (LOF) mutation in an Italian allele of the gene that encodes the transcription factor CBF2, which underlies a major freezing-tolerance locus. We used four lines with a Swedish genetic background, each containing a LOF CBF2 allele. Two lines had introgression segments containing the Italian CBF2 allele, and two contained deletions created using CRISPR-Cas9. We used a growth chamber experiment to quantify freezing tolerance and gene expression before and after cold acclimation. RESULTS Freezing tolerance was lower in the Italian (11%) compared to the Swedish (72%) ecotype, and all four experimental CBF2 LOF lines had reduced freezing tolerance compared to the Swedish ecotype. Differential expression analyses identified 10 genes for which all CBF2 LOF lines, and the IT ecotype had similar patterns of reduced cold responsive expression compared to the SW ecotype. CONCLUSIONS We identified 10 genes that are at least partially regulated by CBF2 that may contribute to the differences in cold-acclimated freezing tolerance between the Italian and Swedish ecotypes. These results provide novel insight into the molecular and physiological mechanisms connecting a naturally occurring sequence polymorphism to an adaptive response to freezing conditions.
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Affiliation(s)
- Brian J. Sanderson
- Department of Botany and Plant Pathology and the Purdue Center for Plant BiologyPurdue UniversityWest LafayetteINUSA
| | - Sunchung Park
- MSU‐DOE Plant Research Laboratory and the Plant Resilience InstituteMichigan State UniversityEast LansingMIUSA
- Present address:
USDA ARS SalinasCAUSA
| | - M. Inam Jameel
- Department of Botany and Plant Pathology and the Purdue Center for Plant BiologyPurdue UniversityWest LafayetteINUSA
- Present address:
Department of GeneticsUniversity of GeorgiaAthensGAUSA
| | - Joshua C. Kraft
- Department of Botany and Plant Pathology and the Purdue Center for Plant BiologyPurdue UniversityWest LafayetteINUSA
| | - Michael F. Thomashow
- MSU‐DOE Plant Research Laboratory and the Plant Resilience InstituteMichigan State UniversityEast LansingMIUSA
| | - Douglas W. Schemske
- Department of Plant Biology, and W. K. Kellogg Biological StationMichigan State UniversityEast LansingMIUSA
| | - Christopher G. Oakley
- Department of Botany and Plant Pathology and the Purdue Center for Plant BiologyPurdue UniversityWest LafayetteINUSA
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Arruda P, Barreto P. Lysine Catabolism Through the Saccharopine Pathway: Enzymes and Intermediates Involved in Plant Responses to Abiotic and Biotic Stress. FRONTIERS IN PLANT SCIENCE 2020; 11:587. [PMID: 32508857 PMCID: PMC7253579 DOI: 10.3389/fpls.2020.00587] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 04/20/2020] [Indexed: 05/14/2023]
Abstract
The saccharopine pathway (SACPATH) involves the conversion of lysine into α-aminoadipate by three enzymatic reactions catalyzed by the bifunctional enzyme lysine-ketoglutarate reductase/saccharopine dehydrogenase (LKR/SDH) and the enzyme α-aminoadipate semialdehyde dehydrogenase (AASADH). The LKR domain condenses lysine and α-ketoglutarate into saccharopine, and the SDH domain hydrolyzes saccharopine to form glutamate and α-aminoadipate semialdehyde, the latter of which is oxidized to α-aminoadipate by AASADH. Glutamate can give rise to proline by the action of the enzymes Δ1-pyrroline-5-carboxylate synthetase (P5CS) and Δ1-pyrroline-5-carboxylate reductase (P5CR), while Δ1-piperideine-6-carboxylate the cyclic form of α-aminoadipate semialdehyde can be used by P5CR to produce pipecolate. The production of proline and pipecolate by the SACPATH can help plants face the damage caused by osmotic, drought, and salt stress. AASADH is a versatile enzyme that converts an array of aldehydes into carboxylates, and thus, its induction within the SACPATH would help alleviate the toxic effects of these compounds produced under stressful conditions. Pipecolate is the priming agent of N-hydroxypipecolate (NHP), the effector of systemic acquired resistance (SAR). In this review, lysine catabolism through the SACPATH is discussed in the context of abiotic stress and its potential role in the induction of the biotic stress response.
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Affiliation(s)
- Paulo Arruda
- Centro de Biologia Molecular e Engenharia Genética, Universidade Estadual de Campinas (UNICAMP), Campinas, Brazil
- Departamento de Genética, Evolução e Bioagentes, Instituto de Biologia, Universidade Estadual de Campinas (UNICAMP), Campinas, Brazil
- Genomics for Climate Change Research Center (GCCRC), Universidade Estadual de Campinas (UNICAMP), Campinas, Brazil
- *Correspondence: Paulo Arruda,
| | - Pedro Barreto
- Centro de Biologia Molecular e Engenharia Genética, Universidade Estadual de Campinas (UNICAMP), Campinas, Brazil
- Departamento de Genética, Evolução e Bioagentes, Instituto de Biologia, Universidade Estadual de Campinas (UNICAMP), Campinas, Brazil
- Genomics for Climate Change Research Center (GCCRC), Universidade Estadual de Campinas (UNICAMP), Campinas, Brazil
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Li N, Uhrig JF, Thurow C, Huang LJ, Gatz C. Reconstitution of the Jasmonate Signaling Pathway in Plant Protoplasts. Cells 2019; 8:cells8121532. [PMID: 31795159 PMCID: PMC6953042 DOI: 10.3390/cells8121532] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2019] [Revised: 11/23/2019] [Accepted: 11/26/2019] [Indexed: 01/11/2023] Open
Abstract
The phytohormone jasmonic acid (JA) plays an important role in various plant developmental processes and environmental adaptations. The JA signaling pathway has been well-elucidated in the reference plant Arabidopsis thaliana. It starts with the perception of the active JA derivative, jasmonoyl-isoleucine (JA-Ile), by the F-box protein COI1 which is part of the E3-ligase SCFCOI1. Binding of JA-Ile enables the interaction between COI1 and JAZ repressor proteins. Subsequent degradation of JAZ proteins leads to the activation of transcription factors like e.g., MYC2. Here we demonstrate that the pathway can be reconstituted in transiently transformed protoplasts. Analysis of the stability of a JAZ1-fLuc fusion protein as a function of COI1 transiently expressed in coi1 protoplasts allows structure function analysis of both JAZs and COI1. Using this system, we found that conserved cysteines in COI1 influence steady state COI1 protein levels. Using a luciferase reporter gene under the control of the JAZ1 promoter enable to address those features of JAZ1 that are required for MYC2 repression. Interestingly, the conserved TIFY-motif previously described to interact with NINJA to recruit the corepressor TOPLESS is not necessary for repression. This result is in favor of the alternative repression mode that proposes a direct competition between repressive JAZs and promotive MEDIATOR25 at MYC2. Finally, using protoplasts from the aos coi1 double mutant, which is deficient in JA synthesis and perception, we provide a system that has the potential to study the activity of different COI1 variants in the presence of different ligands.
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Affiliation(s)
- Ning Li
- State Key Laboratory of Cultivation and Protection for Non-Wood Forest Trees, Ministry of Education, Central South University of Forestry and Technology, Hunan 410004, China;
- College of Forestry, Central South University of Forestry and Technology, Hunan 410004, China
- Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University Göttingen, 37077 Göttingen, Germany; (J.F.U.); (C.T.)
| | - Joachim F. Uhrig
- Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University Göttingen, 37077 Göttingen, Germany; (J.F.U.); (C.T.)
| | - Corinna Thurow
- Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University Göttingen, 37077 Göttingen, Germany; (J.F.U.); (C.T.)
| | - Li-Jun Huang
- College of Forestry, Central South University of Forestry and Technology, Hunan 410004, China
- Correspondence: (L.-J.H.); (C.G.)
| | - Christiane Gatz
- Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University Göttingen, 37077 Göttingen, Germany; (J.F.U.); (C.T.)
- Correspondence: (L.-J.H.); (C.G.)
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Hawkins LJ, Storey KB. Advances and applications of environmental stress adaptation research. Comp Biochem Physiol A Mol Integr Physiol 2019; 240:110623. [PMID: 31778815 DOI: 10.1016/j.cbpa.2019.110623] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 11/19/2019] [Accepted: 11/21/2019] [Indexed: 02/06/2023]
Abstract
Evolution has produced animals that survive extreme fluctuations in environmental conditions including freezing temperatures, anoxia, desiccating conditions, and prolonged periods without food. For example, the wood frog survives whole-body freezing every winter, arresting all gross physiological functions, but recovers functions upon thawing in the spring. Likewise, many small mammals hibernate for months at a time with minimal metabolic activity, organ perfusion, and movement, yet do not suffer significant muscle atrophy upon arousal. These conditions and the biochemical adaptations employed to deal with them can be viewed as Nature's answer to problems that humans wish to answer, particularly in a biomedical context. This review focuses on recent advances in the field of animal environmental stress adaptation, starting with an emphasis on new areas of research such as epigenetics and microRNA. We then examine new and emerging technologies such as genome editing, novel sequencing applications, and single cell analysis and how these can push us closer to a deeper understanding of biochemical adaptation. Next, evaluate the potential contributions of new high-throughput technologies (e.g. next-generation sequencing, mass spectrometry proteomics) to better understanding the adaptations that support these extreme phenotypes. Concluding, we examine some of the human applications that can be gained from understanding the principles of biochemical adaptation including organ preservation and treatments for conditions such as ischemic stroke and muscle disuse atrophy.
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Affiliation(s)
- Liam J Hawkins
- Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada
| | - Kenneth B Storey
- Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada.
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