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Das A, Dedon N, Enders DJ, Fjellheim S, Preston JC. Testing the chilling- before drought-tolerance hypothesis in Pooideae grasses. Mol Ecol 2023; 32:772-785. [PMID: 36420966 PMCID: PMC10107940 DOI: 10.1111/mec.16794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 11/16/2022] [Accepted: 11/22/2022] [Indexed: 11/25/2022]
Abstract
Temperate Pooideae are a large clade of economically important grasses distributed in some of the Earth's coldest and driest terrestrial environments. Previous studies have inferred that Pooideae diversified from their tropical ancestors in a cold montane habitat, suggesting that above-freezing cold (chilling) tolerance evolved early in the subfamily. By contrast, drought tolerance is hypothesized to have evolved multiple times independently in response to global aridification that occurred after the split of Pooideae tribes. To independently test predictions of the chilling-before-drought hypothesis in Pooideae, we assessed conservation of whole plant and gene expression traits in response to chilling vs. drought. We demonstrated that both trait responses are more similar across tribes in cold as compared to drought, suggesting that chilling responses evolved before, and drought responses after, tribe diversification. Moreover, we found significantly more overlap between drought and chilling responsive genes within a species than between drought responsive genes across species, providing evidence that chilling tolerance genes acted as precursors for the novel acquisition of increased drought tolerance multiple times independently, partially through the cooption of chilling responsive genes.
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Affiliation(s)
- Aayudh Das
- Department of Plant Biology, The University of Vermont, Burlington, Vermont, USA
| | - Natalie Dedon
- Department of Plant Biology, The University of Vermont, Burlington, Vermont, USA
| | - Daniel J Enders
- Department of Plant Biology, The University of Vermont, Burlington, Vermont, USA
| | - Siri Fjellheim
- Department of Plant Sciences, Faculty of Biosciences, Norwegian University of Life Sciences, Ås, Norway
| | - Jill C Preston
- Department of Plant Biology, The University of Vermont, Burlington, Vermont, USA
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Georgieva K, Mihailova G, Fernández-Marín B, Bertazza G, Govoni A, Arzac MI, Laza JM, Vilas JL, García-Plazaola JI, Rapparini F. Protective Strategies of Haberlea rhodopensis for Acquisition of Freezing Tolerance: Interaction between Dehydration and Low Temperature. Int J Mol Sci 2022; 23:ijms232315050. [PMID: 36499377 PMCID: PMC9739172 DOI: 10.3390/ijms232315050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 11/28/2022] [Accepted: 11/28/2022] [Indexed: 12/05/2022] Open
Abstract
Resurrection plants are able to deal with complete dehydration of their leaves and then recover normal metabolic activity after rehydration. Only a few resurrection species are exposed to freezing temperatures in their natural environments, making them interesting models to study the key metabolic adjustments of freezing tolerances. Here, we investigate the effect of cold and freezing temperatures on physiological and biochemical changes in the leaves of Haberlea rhodopensis under natural and controlled environmental conditions. Our data shows that leaf water content affects its thermodynamical properties during vitrification under low temperatures. The changes in membrane lipid composition, accumulation of sugars, and synthesis of stress-induced proteins were significantly activated during the adaptation of H. rhodopensis to both cold and freezing temperatures. In particular, the freezing tolerance of H. rhodopensis relies on a sucrose/hexoses ratio in favor of hexoses during cold acclimation, while there is a shift in favor of sucrose upon exposure to freezing temperatures, especially evident when leaf desiccation is relevant. This pattern was paralleled by an elevated ratio of unsaturated/saturated fatty acids and significant quantitative and compositional changes in stress-induced proteins, namely dehydrins and early light-induced proteins (ELIPs). Taken together, our data indicate that common responses of H. rhodopensis plants to low temperature and desiccation involve the accumulation of sugars and upregulation of dehydrins/ELIP protein expression. Further studies on the molecular mechanisms underlying freezing tolerance (genes and genetic regulatory mechanisms) may help breeders to improve the resistance of crop plants.
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Affiliation(s)
- Katya Georgieva
- Institute of Plant Physiology and Genetics, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 21, 1113 Sofia, Bulgaria
- Correspondence: ; Tel.: +359-2-979-2620
| | - Gergana Mihailova
- Institute of Plant Physiology and Genetics, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 21, 1113 Sofia, Bulgaria
| | - Beatriz Fernández-Marín
- Department of Botany, Ecology and Plant Physiology, University of La Laguna (ULL), 38200 Tenerife, Spain
| | - Gianpaolo Bertazza
- Bioeconomy Institute (IBE), Department of Bio-Agrifood Science (DiSBA), National Research Council (CNR), Via P. Gobetti 101, I-40129 Bologna, Italy
| | - Annalisa Govoni
- Bioeconomy Institute (IBE), Department of Bio-Agrifood Science (DiSBA), National Research Council (CNR), Via P. Gobetti 101, I-40129 Bologna, Italy
| | - Miren Irati Arzac
- Department of Plant Biology and Ecology, University of the Basque Country (UPV/EHU), Barrio Sarriena s/n, 48940 Bilbao, Spain
| | - José Manuel Laza
- Department of Physical Chemistry, University of the Basque Country (UPV/EHU), Barrio Sarriena s/n, 48940 Bilbao, Spain
| | - José Luis Vilas
- Department of Physical Chemistry, University of the Basque Country (UPV/EHU), Barrio Sarriena s/n, 48940 Bilbao, Spain
| | - José Ignacio García-Plazaola
- Department of Plant Biology and Ecology, University of the Basque Country (UPV/EHU), Barrio Sarriena s/n, 48940 Bilbao, Spain
| | - Francesca Rapparini
- Bioeconomy Institute (IBE), Department of Bio-Agrifood Science (DiSBA), National Research Council (CNR), Via P. Gobetti 101, I-40129 Bologna, Italy
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Lintunen A, Salmon Y, Hölttä T, Suhonen H. Inspection of gas bubbles in frozen Betula pendula xylem with micro‐CT: Conduit size, water status and bark permeability affect bubble characteristics. PHYSIOLOGIA PLANTARUM 2022. [PMCID: PMC9540547 DOI: 10.1111/ppl.13749] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Bubbles of gas trapped in the xylem during freezing are a major cause of damage for trees growing at high altitudes or latitudes, as the bubbles may cause embolism during thawing. Yet the factors controlling bubble formation upon freeze–thaw cycles remain poorly understood. Especially the size of the bubbles formed in the ice is crucial for winter embolism formation. We used high‐resolution X‐ray microtomography combined with freezing experiments to investigate the size and shape of 68,343 gas bubbles in frozen conduits in branches of Betula pendula. We also studied how conduit size, tree water status (−0.2 MPa vs. −0.6 MPa) and bark permeability to gases (decreased by Vaseline‐coating) affect the gas bubbles characteristics. High‐resolution X‐ray images allowed us to detect gas bubbles down to 1.0 μm in diameter and revealed that not only small spherical gas bubbles but also gaseous volumes of various shapes and sizes were found from the frozen xylem indicating that gas bubbles may have started to grow already during the freezing propagation. Most of the gas bubbles were found in fibers, but the rare gas bubbles found in the vessels were larger than those in the fibers. Bubble volume increased with conduit volume in both fibers and vessels, but conduit size alone could not explain gas bubble volume. Low water potential and restriction of gas escape from the branch seem to cause more, larger, and less spherical bubbles and thus increase the risk of embolism formation. These findings open new research avenues for further studies of winter embolism formation.
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Affiliation(s)
- Anna Lintunen
- Institute for Atmospheric and Earth System Research/Physics, Faculty of ScienceUniversity of HelsinkiHelsinkiFinland
- Institute for Atmospheric and Earth System Research/Forest Sciences, Faculty of Agriculture and ForestryUniversity of HelsinkiHelsinkiFinland
| | - Yann Salmon
- Institute for Atmospheric and Earth System Research/Physics, Faculty of ScienceUniversity of HelsinkiHelsinkiFinland
- Institute for Atmospheric and Earth System Research/Forest Sciences, Faculty of Agriculture and ForestryUniversity of HelsinkiHelsinkiFinland
| | - Teemu Hölttä
- Institute for Atmospheric and Earth System Research/Forest Sciences, Faculty of Agriculture and ForestryUniversity of HelsinkiHelsinkiFinland
| | - Heikki Suhonen
- Department of PhysicsUniversity of HelsinkiHelsinkiFinland
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Jin M, Gan S, Jiao J, He Y, Liu H, Yin X, Zhu Q, Rao J. Genome-wide analysis of the bZIP gene family and the role of AchnABF1 from postharvest kiwifruit (Actinidia chinensis cv. Hongyang) in osmotic and freezing stress adaptations. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2021; 308:110927. [PMID: 34034875 DOI: 10.1016/j.plantsci.2021.110927] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 04/17/2021] [Accepted: 04/25/2021] [Indexed: 05/21/2023]
Abstract
Chilling injury (CI) is a barrier to the refrigeration of kiwifruit, resulting in decreased fruit quality and increased nutrient loss during storage. Understanding the molecular basis underlying the cold response and its regulation in refrigerated kiwifruit is therefore highly important. Basic (region) leucine zipper (bZIP) transcription factors (TFs) have been widely studied for their roles in abiotic stress resistance in various species. In this study, we identified 81 bZIP family proteins in kiwifruit and classified them into 11 groups. Further transcriptome analysis revealed that the expression of members of the AREB/ABF family was strongly induced by low temperature and abscisic acid (ABA). Ectopic expression of AchnABF1 enhanced plant cold tolerance by upregulating the expression of several key genes associated with ABA-dependent and ABA-independent pathways in Arabidopsis thaliana. Reactive oxygen species (ROS) metabolism was suggested to be involved in the AchnABF1-mediated osmotic stress response. For instance, enhanced ROS-scavenging ability was observed in transgenic plants with enhanced activity of catalase (CAT) and peroxidase (POD), which resulted in decreased in situ O2.- and H2O2 accumulation, ion leakage, and malondialdehyde (MDA) content under various abiotic stresses. In addition, AchnABF1 also participated in the osmotic stress response during both the germination and postgermination stages. We concluded that AchnABF1 may play an important role in kiwifruit during refrigeration.
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Affiliation(s)
- Mijing Jin
- College of Horticulture, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Sufu Gan
- Biotechnology of Horticultural Crops, TUM School for Life Sciences Weihenstephan, Technische Universität München, Freising, D-85354, Germany
| | - Jianqing Jiao
- College of Horticulture, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Yiheng He
- College of Horticulture, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Hui Liu
- College of Horticulture, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Xueren Yin
- Zhejiang Provincial Key Laboratory of Horticultural Plant Integrative Biology, Zhejiang University, Zijingang Campus, Hangzhou, China
| | - Qinggang Zhu
- College of Horticulture, Northwest A&F University, Yangling, Shaanxi, 712100, China.
| | - Jingping Rao
- College of Horticulture, Northwest A&F University, Yangling, Shaanxi, 712100, China.
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6
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Trewavas A. Awareness and integrated information theory identify plant meristems as sites of conscious activity. PROTOPLASMA 2021; 258:673-679. [PMID: 33745091 PMCID: PMC8052216 DOI: 10.1007/s00709-021-01633-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2020] [Accepted: 03/04/2021] [Indexed: 05/02/2023]
Abstract
Lacking an anatomical brain/nervous system, it is assumed plants are not conscious. The biological function of consciousness is an input to behaviour; it is adaptive (subject to selection) and based on information. Complex language makes human consciousness unique. Consciousness is equated to awareness. All organisms are aware of their surroundings, modifying their behaviour to improve survival. Awareness requires assessment too. The mechanisms of animal assessment are neural while molecular and electrical in plants. Awareness of plants being also consciousness may resolve controversy. The integrated information theory (IIT), a leading theory of consciousness, is also blind to brains, nerves and synapses. The integrated information theory indicates plant awareness involves information of two kinds: (1) communicative, extrinsic information as a result of the perception of environmental changes and (2) integrated intrinsic information located in the shoot and root meristems and possibly cambium. The combination of information constructs an information nexus in the meristems leading to assessment and behaviour. The interpretation of integrated information in meristems probably involves the complex networks built around [Ca2+]i that also enable plant learning, memory and intelligent activities. A mature plant contains a large number of conjoined, conscious or aware, meristems possibly unique in the living kingdom.
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Affiliation(s)
- Anthony Trewavas
- Institute of Molecular Plant Science, University of Edinburgh, EH9 3JH, Edinburgh, Scotland.
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di Francescantonio D, Villagra M, Goldstein G, Campanello PI. Drought and frost resistance vary between evergreen and deciduous Atlantic Forest canopy trees. FUNCTIONAL PLANT BIOLOGY : FPB 2020; 47:779-791. [PMID: 32513382 DOI: 10.1071/fp19282] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2019] [Accepted: 03/27/2020] [Indexed: 06/11/2023]
Abstract
Frost and drought are key stress factors limiting the growth and distribution of tree species. Resistance to stress involves energy costs that may result in trade-offs between different functional traits. Structures or mechanisms that can help to withstand stress imply differences in the carbon economy of the species. Although adaptive responses to frost and drought resistance are usually of a similar nature, they are rarely assessed simultaneously. We investigated these resistance mechanisms in 10 canopy tree species coexisting in the semi-deciduous subtropical forests of northern Argentina. We measured leaf lifespan, anatomical, photosynthetic and water relations traits and performed a thermal analysis in leaves to determined ice nucleation and tissue damage temperatures. Our results showed that evergreen and deciduous species have different adaptive responses to cope with freezing temperatures and water deficits. Evergreen species exhibited cold tolerance, while deciduous species were more resistant to hydraulic dysfunction and showed greater water transport efficiency. Further research is needed to elucidate resistance strategies to stress factors at the whole tree- and stand level, and possible links with hydraulic safety and efficiency among different phenological groups. This will allow us to predict the responses of subtropical forest species to changes in environmental conditions under climate change scenarios.
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Affiliation(s)
- Débora di Francescantonio
- Laboratorio de Ecología Forestal y Ecofisiología, Instituto de Biología Subtropical, Universidad Nacional de Misiones (UNaM)-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). Bertoni 85, Puerto Iguazú (N3370BFA), Misiones, Argentina; and Asociación Civil Centro de Investigaciones del Bosque Atlántico (CeIBA). Bertoni 85, Puerto Iguazú (N3370BFA), Misiones, Argentina; and Corresponding author.
| | - Mariana Villagra
- Laboratorio de Ecología Forestal y Ecofisiología, Instituto de Biología Subtropical, Universidad Nacional de Misiones (UNaM)-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). Bertoni 85, Puerto Iguazú (N3370BFA), Misiones, Argentina; and Asociación Civil Centro de Investigaciones del Bosque Atlántico (CeIBA). Bertoni 85, Puerto Iguazú (N3370BFA), Misiones, Argentina
| | - Guillermo Goldstein
- Laboratorio de Ecología Funcional, Instituto de Ecología, Genética y Evolución, Instituto IEGEBA (CONICET-UBA), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, CABA, C1428EGA, Argentina
| | - Paula I Campanello
- Laboratorio de Ecología Forestal y Ecofisiología, Instituto de Biología Subtropical, Universidad Nacional de Misiones (UNaM)-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). Bertoni 85, Puerto Iguazú (N3370BFA), Misiones, Argentina; and Centro de Estudios Ambientales Integrados, Facultad de Ingeniería, Universidad Nacional de la Patagonia San Juan Bosco, CONICET, RN Nº 259 - Km 16.4, Esquel (9200), Chubut, Argentina
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Huang H, Anderegg LDL, Dawson TE, Mote S, D'Odorico P. Critical transition to woody plant dominance through microclimate feedbacks in North American coastal ecosystems. Ecology 2020; 101:e03107. [PMID: 32452021 DOI: 10.1002/ecy.3107] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Revised: 03/17/2020] [Accepted: 04/21/2020] [Indexed: 11/10/2022]
Abstract
Climate warming is facilitating the expansion of many cold-sensitive woody species in woodland-grassland ecotones worldwide. Recent research has demonstrated that this range expansion can be further enhanced by positive vegetation-microclimate feedbacks whereby woody canopies induce local nocturnal warming, which reduces freeze-induced damage and favors the establishment of woody plants. However, this local positive feedback can be counteracted by biotic drivers such as browsing and the associated consumption of shrub biomass. The joint effects of large-scale climate warming and local-scale microclimate feedbacks on woody vegetation dynamics in these ecotones remain poorly understood. Here, we used a combination of experimental and modeling approaches to investigate the effects of woody cover on microclimate and the consequent implications on ecological stability in North American coastal ecosystems. We found greater browsing pressure and significant warming (~2°C) beneath shrub canopies compared to adjacent grasslands, which reduces shrub seedlings' exposure to cold damage. Cold sensitivity is evidenced by the significant decline in xylem hydraulic conductivity in shrub seedlings when temperatures dropped below -2°C. Despite the negative browsing-vegetation feedback, a small increase in minimum temperature can induce critical transitions from grass to woody plant dominance. Our framework also predicts the threshold temperature of -7°C for mangrove-salt marsh ecotones on the Atlantic coast of Florida. Above this reference temperature a critical transition may occur from salt marsh to mangrove vegetation, in agreement with empirical studies. Thus, the interaction between ongoing global warming trends and microclimate feedbacks may significantly alter woody vegetation dynamics and ecological stability in coastal ecosystems where woody plant expansion is primarily constrained by extreme low temperature events.
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Affiliation(s)
- Heng Huang
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, California, 94720, USA
| | - Leander D L Anderegg
- Department of Integrative Biology, University of California, Berkeley, California, 94720, USA.,Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, California, 93106, USA
| | - Todd E Dawson
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, California, 94720, USA.,Department of Integrative Biology, University of California, Berkeley, California, 94720, USA
| | - Safa Mote
- Department of Atmospheric and Oceanic Science, University of Maryland, College Park, Maryland, 20742, USA.,Institute for Physical Science and Technology, University of Maryland, College Park, Maryland, 20742, USA.,Department of Physics, University of Maryland, College Park, Maryland, 20742, USA
| | - Paolo D'Odorico
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, California, 94720, USA
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Wood LK, Hays S, Zinnert JC. Decreased temperature variance associated with biotic composition enhances coastal shrub encroachment. Sci Rep 2020; 10:8210. [PMID: 32427910 PMCID: PMC7237465 DOI: 10.1038/s41598-020-65161-3] [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: 12/10/2019] [Accepted: 04/28/2020] [Indexed: 11/09/2022] Open
Abstract
Regime shift from grasslands to shrub-dominated landscapes occur worldwide driven by altered land-use and climate change, affecting landscape function, biodiversity, and productivity. Warming winter temperatures are a main driver of expansion of the native, evergreen shrub, Morella cerifera, in coastal landscapes. Shrub establishment in these habitats alters microclimate, but little is known about seasonal differences and microclimate variance. We assessed influence of shrubs on microclimate variance, community composition, and community physiological functioning across three vegetation zones: grass, transitional, and shrub in a coastal grassland. Using a novel application of a time-series analysis, we interpret microclimatic variance modification and elucidate mechanisms of shrub encroachment at the Virginia Coast Reserve, Long-Term Ecological Research site. As shrub thickets form, diversity is reduced with little grass/forb cover, while transpiration and annual productivity increase. Shrub thickets significantly reduced temperature variance with a positive influence of one day on the next in maximum air, minimum air, and maximum ground temperature. We also show that microclimatic temperature moderation reduces summer extreme temperatures in transition areas, even before coalescence into full thickets. Encroachment of Morella cerifera on the Virginia barrier islands is driven by reduced local exposure to cold temperatures and enhanced by abiotic microclimatic modification and biotic physiological functioning. This shift in plant community composition from grassland to shrub thicket alters the role of barrier islands in productivity and can have impacts on the natural resilience of the islands.
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Affiliation(s)
- Lauren K Wood
- Department of Biology, Virginia Commonwealth University, 1000 West Cary St, Richmond, VA, 23225, USA.,Integrative Life Sciences Doctoral Program, Virginia Commonwealth University, 1000 West Cary St, Richmond, VA, 23225, USA
| | - Spencer Hays
- Department of Statistics, Indiana University, 919 E. 10th St, Bloomington, IN, 47408, USA
| | - Julie C Zinnert
- Department of Biology, Virginia Commonwealth University, 1000 West Cary St, Richmond, VA, 23225, USA.
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Sinclair MN, Woods NN, Zinnert JC. Seasonal facilitative and competitive trade‐offs between shrub seedlings and coastal grasses. Ecosphere 2020. [DOI: 10.1002/ecs2.2995] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
- Michael N. Sinclair
- Department of Biology Virginia Commonwealth University 1000 W Cary Street Richmond Virginia 23284 USA
| | - Natasha N. Woods
- Department of Biology Virginia Commonwealth University 1000 W Cary Street Richmond Virginia 23284 USA
| | - Julie C. Zinnert
- Department of Biology Virginia Commonwealth University 1000 W Cary Street Richmond Virginia 23284 USA
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11
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Deacon NJ, Grossman JJ, Cavender‐Bares J. Drought and freezing vulnerability of the isolated hybrid aspen Populus x smithii relative to its parental species, P. tremuloides and P. grandidentata. Ecol Evol 2019; 9:8062-8074. [PMID: 31380071 PMCID: PMC6662423 DOI: 10.1002/ece3.5364] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Revised: 05/09/2019] [Accepted: 05/14/2019] [Indexed: 11/12/2022] Open
Abstract
AIM We assessed the vulnerability of an isolated, relictual Pleistocene hybrid aspen population of conservation interest (Populus x. smithii) and the nearest populations of its parent species (Populus grandidentata and Populus tremuloides) to springtime post-bud break freezing and growing season drought stress. Response to these stressors in the three taxa was compared in terms of avoidance and tolerance. LOCATION North American Midwest; USA. METHODS Unique genets from the hybrid Niobrara River population and from the two parental populations were propagated in a common garden from rhizome cuttings. We tracked their phenology before and after bud break and measured their vulnerability to freezing (stem electrolyte leakage and leaf chlorophyll fluorescence) and to drought (stem hydraulic conductance, leaf osmotic potential, stomatal pore index, and gas exchange). RESULTS Populus grandidentata was slower to leaf out, showed lower vulnerability to stem freezing and drought-induced cavitation, but exhibited a lower capacity to tolerate drought stress through leaf resistance traits compared to P. tremuloides. Hybrids were similar to P. grandidentata in their overwintering strategy, exhibiting later bud break, and in their higher resistance to stem freezing damage, but they were more similar to P. tremuloides in their higher vulnerability to drought-induced cavitation. The hybrids shared various leaf-level gas exchange traits with both parents. All aspens showed limited loss of leaf photosynthetic function following moderate freezing. MAIN CONCLUSIONS The Niobrara River hybrid population is vulnerable to drought due to its combination of inherited drought avoidance and tolerance traits. As climate changes, P. x smithii will likely suffer from increased drought stress, while being unaffected by frost during warmer springs. The two parental species contrast in their survival mechanisms in response to climatic stress, with P. tremuloides tending toward freezing tolerance but drought avoidance and P. grandidentata tending toward freezing avoidance and drought tolerance.
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Affiliation(s)
- Nicholas J. Deacon
- Department of Ecology, Evolution, and BehaviorUniversity of MinnesotaSt. PaulMinnesota
- Present address:
Minneapolis Community and Technical College1501 Hennepin AvenueMinneapolis55403MN
| | - Jake J. Grossman
- Department of Ecology, Evolution, and BehaviorUniversity of MinnesotaSt. PaulMinnesota
- Present address:
Arnold Arboretum of Harvard University125 ArborwayBoston02130MA
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12
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Huang H, Zinnert JC, Wood LK, Young DR, D'Odorico P. Non-linear shift from grassland to shrubland in temperate barrier islands. Ecology 2018; 99:1671-1681. [PMID: 29729181 DOI: 10.1002/ecy.2383] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Revised: 03/03/2018] [Accepted: 04/05/2018] [Indexed: 11/10/2022]
Abstract
Woody plant encroachment into grasslands is a major land cover change taking place in many regions of the world, including arctic, alpine and desert ecosystems. This change in plant dominance is also affecting coastal ecosystems, including barrier islands, which are known for being vulnerable to the effects of climate change. In the last century, the woody plant species Morella cerifera L. (Myricaceae), has encroached into grass covered swales in many of the barrier islands of Virginia along the Atlantic seaboard. The abrupt shift to shrub cover in these islands could result from positive feedbacks with the physical environment, though the underlying mechanisms remain poorly understood. We use a combination of experimental and modeling approaches to investigate the role of climate warming and the ability of M. cerifera to mitigate its microclimate thereby leading to the emergence of alternative stable states in barrier island vegetation. Nighttime air temperatures were significantly higher in myrtle shrublands than grasslands, particularly in the winter season. The difference in the mean of the 5% and 10% lowest minimum temperatures between shrubland and grassland calculated from two independent datasets ranged from 1.3 to 2.4°C. The model results clearly show that a small increase in near-surface temperature can induce a non-linear shift in ecosystem state from a stable state with no shrubs to an alternative stable state dominated by M. cerifera. This modeling framework improves our understanding and prediction of barrier island vegetation stability and resilience under climate change, and highlights the existence of important nonlinearities and hystereses that limit the reversibility of this ongoing shift in vegetation dominance.
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Affiliation(s)
- Heng Huang
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, California, 94720-3116, USA
| | - Julie C Zinnert
- Department of Biology, Virginia Commonwealth University, Richmond, Virginia, 23284, USA
| | - Lauren K Wood
- Department of Biology, Virginia Commonwealth University, Richmond, Virginia, 23284, USA
| | - Donald R Young
- Department of Biology, Virginia Commonwealth University, Richmond, Virginia, 23284, USA
| | - Paolo D'Odorico
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, California, 94720-3116, USA
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Medeiros JS, Danielson SC. Renewed interest in whole-plant physiology sheds light on the complexity of plant stress response architecture. TREE PHYSIOLOGY 2018; 38:503-506. [PMID: 29474704 DOI: 10.1093/treephys/tpy018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Accepted: 01/25/2018] [Indexed: 06/08/2023]
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14
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Fernández-Pérez L, Villar-Salvador P, Martínez-Vilalta J, Toca A, Zavala MA. Distribution of pines in the Iberian Peninsula agrees with species differences in foliage frost tolerance, not with vulnerability to freezing-induced xylem embolism. TREE PHYSIOLOGY 2018; 38:507-516. [PMID: 29325114 DOI: 10.1093/treephys/tpx171] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Accepted: 12/09/2017] [Indexed: 06/07/2023]
Abstract
Drought and frosts are major determinants of plant functioning and distribution. Both stresses can cause xylem embolism and foliage damage. The objective of this study was to analyse if the distribution of six common pine species along latitudinal and altitudinal gradients in Europe is related to their interspecific differences in frost tolerance and to the physiological mechanisms underlying species-specific frost tolerance. We also evaluate if frost tolerance depends on plant water status. We studied survival to a range of freezing temperatures in 2-year-old plants and assessed the percentage loss of hydraulic conductivity (PLC) due xylem embolism formation and foliage damage determined by needle electrolyte leakage (EL) after a single frost cycle to -15 °C and over a range of predawn water potential (ψpd) values. Species experiencing cold winters in their range (Pinus nigra J.F. Arnold, Pinus sylvestris L. and Pinus uncinata Raymond ex A. DC.) had the highest frost survival rates and lowest needle EL and soluble sugar (SS) concentration. In contrast, the pines inhabiting mild or cool winter locations (especially Pinus halepensis Mill. and Pinus pinea L. and, to a lesser extent, Pinus pinaster Ait.) had the lowest frost survival and highest needle EL and SS values. Freezing-induced PLC was very low and differences among species were not related to frost damage. Reduction in ψpd decreased leaf frost damage in P. pinea and P. sylvestris, increased it in P. uncinata and had a neutral effect on the rest of the species. This study demonstrates that freezing temperatures are a major environmental driver for pine distribution and suggests that interspecific differences in leaf frost sensitivity rather than vulnerability to freezing-induced embolism or SS explain pine juvenile frost survival.
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Affiliation(s)
- Laura Fernández-Pérez
- Forest Ecology and Restoration Group, Departmento de Ciencias de la Vida, Universidad de Alcalá, Apdo 20, Alcalá de Henares, 28805 Madrid, Spain
| | - Pedro Villar-Salvador
- Forest Ecology and Restoration Group, Departmento de Ciencias de la Vida, Universidad de Alcalá, Apdo 20, Alcalá de Henares, 28805 Madrid, Spain
| | - Jordi Martínez-Vilalta
- CREAF, Campus UAB, Edifici C, Cerdanyola del Vallès 08193, Barcelona, Spain
- Departament de Biologia Animal, de Biologia Vegetal i d'Ecologia, Univ. Autònoma Barcelona, Edifici C, Cerdanyola del Vallès 08193, Barcelona, Spain
| | - Andrei Toca
- Forest Ecology and Restoration Group, Departmento de Ciencias de la Vida, Universidad de Alcalá, Apdo 20, Alcalá de Henares, 28805 Madrid, Spain
| | - Miguel A Zavala
- Forest Ecology and Restoration Group, Departmento de Ciencias de la Vida, Universidad de Alcalá, Apdo 20, Alcalá de Henares, 28805 Madrid, Spain
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Kong RS, Henry HAL. Does cross-acclimation between drought and freezing stress persist over ecologically relevant time spans? A test using the grass Poa pratensis. PLANT BIOLOGY (STUTTGART, GERMANY) 2018; 20:280-287. [PMID: 29148214 DOI: 10.1111/plb.12667] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Accepted: 11/13/2017] [Indexed: 06/07/2023]
Abstract
Despite evidence that prior exposure to drought can increase subsequent plant freezing tolerance, few studies have explored such interactions over ecologically relevant time spans. We examined the combined effects of drought and subsequent freezing on tiller growth and leaf sugar concentrations in the grass, Poa pratensis. We exposed tillers to no drought (-0.04 MPa), moderate drought (-0.19 MPa) or severe drought (-0.42 MPa) for 3 weeks in summer. Tillers were then frozen in autumn or spring at -5 °C (frost damage) or at 0 °C (control) for 3 days and harvested after a re-growth period. For shoot growth, there was a significant interaction between drought and autumn freezing, whereby the relative effect of freezing on growth was least for the plants previously exposed to severe drought; however, there was no significant interaction between drought and spring freezing. For root growth, there were no significant interactions between drought and freezing in either season. Leaf sugar concentrations increased significantly with drought intensity, but these effects dissipated within a month, prior to the onset of the autumn freezing treatment. Overall, our results suggest that interactions between prior drought and subsequent freezing in P. pratensis may be most relevant in the context of autumn freezing, and despite the important role of soluble sugars in increasing both drought and freezing tolerance in this species, the retention of these compounds after drought stress does not appear to explain the occurrence of drought-frost interactions at ecologically relevant time scales.
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Affiliation(s)
- R S Kong
- Department of Biology, University of Western Ontario, London, ON, Canada
| | - H A L Henry
- Department of Biology, University of Western Ontario, London, ON, Canada
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16
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Hudson PJ, Limousin JM, Krofcheck DJ, Boutz AL, Pangle RE, Gehres N, McDowell NG, Pockman WT. Impacts of long-term precipitation manipulation on hydraulic architecture and xylem anatomy of piñon and juniper in Southwest USA. PLANT, CELL & ENVIRONMENT 2018; 41:421-435. [PMID: 29215745 DOI: 10.1111/pce.13109] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Revised: 11/09/2017] [Accepted: 11/14/2017] [Indexed: 06/07/2023]
Abstract
Hydraulic architecture imposes a fundamental control on water transport, underpinning plant productivity, and survival. The extent to which hydraulic architecture of mature trees acclimates to chronic drought is poorly understood, limiting accuracy in predictions of forest responses to future droughts. We measured seasonal shoot hydraulic performance for multiple years to assess xylem acclimation in mature piñon (Pinus edulis) and juniper (Juniperus monosperma) after 3+ years of precipitation manipulation. Our treatments consisted of water addition (+20% ambient precipitation), partial precipitation-exclusion (-45% ambient precipitation), and exclusion-structure control. Supplemental watering elevated leaf water potential, sapwood-area specific hydraulic conductivity, and leaf-area specific hydraulic conductivity relative to precipitation exclusion. Shifts in allocation of leaf area to sapwood area enhanced differences between irrigated and droughted KL in piñon but not juniper. Piñon and juniper achieved similar KL under ambient conditions, but juniper matched or outperformed piñon in all physiological measurements under both increased and decreased precipitation treatments. Embolism vulnerability and xylem anatomy were unaffected by treatments in either species. Absence of significant acclimation combined with inferior performance for both hydraulic transport and safety suggests piñon has greater risk of local extirpation if aridity increases as predicted in the southwestern USA.
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Affiliation(s)
- P J Hudson
- Department of Biology, MSC03 2020, University of New Mexico, Albuquerque, NM, 87131-0001, USA
| | - J M Limousin
- Centre d'Ecologie Fonctionnelle et Evolutive CEFE, UMR5175, CNRS, Université de Montpellier, Université Paul-Valéry Montpellier, Montpellier, 34293, France
| | - D J Krofcheck
- Department of Biology, MSC03 2020, University of New Mexico, Albuquerque, NM, 87131-0001, USA
| | - A L Boutz
- Department of Biology, MSC03 2020, University of New Mexico, Albuquerque, NM, 87131-0001, USA
| | - R E Pangle
- Department of Biology, MSC03 2020, University of New Mexico, Albuquerque, NM, 87131-0001, USA
| | - N Gehres
- Department of Biology, MSC03 2020, University of New Mexico, Albuquerque, NM, 87131-0001, USA
| | - N G McDowell
- Earth Systems Analysis and Modeling, Pacific Northwest National Laboratory, Richland, WA, 99352, USA
| | - W T Pockman
- Department of Biology, MSC03 2020, University of New Mexico, Albuquerque, NM, 87131-0001, USA
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Pan L, Meng C, Wang J, Ma X, Fan X, Yang Z, Zhou M, Zhang X. Integrated omics data of two annual ryegrass (Lolium multiflorum L.) genotypes reveals core metabolic processes under drought stress. BMC PLANT BIOLOGY 2018; 18:26. [PMID: 29378511 PMCID: PMC5789592 DOI: 10.1186/s12870-018-1239-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Accepted: 01/17/2018] [Indexed: 05/18/2023]
Abstract
BACKGROUND Annual ryegrass (Lolium multiflorum L.) is a commercially important, widely distributed forage crop that is used in the production of hay and silage worldwide. Drought has been a severe environmental constraint in its production. Nevertheless, only a handful of studies have examined the impact of short-term drought stress on annual ryegrass. The aim of this study was to explore how stress-induced core metabolic processes enhance drought tolerance, or adaptation to drought, in annual ryegrass. RESULTS We profiled the transcriptomes, proteomes, and metabolomes of two annual ryegrass genotypes: the drought-resistant genotype "Abundant 10" and drought-susceptible genotype "Adrenalin 11." We identified differentially expressed metabolites and their corresponding proteins and transcripts that are involved in 23 core metabolic processes, in response to short-term drought stress. Protein-gene-metabolite correlation networks were built to reveal the relationships between the expression of transcripts, proteins, and metabolites in drought-resistant annual ryegrass. Furthermore, integrated metabolic pathways were used to observe changes in enzymes corresponding with levels of amino acids, lipids, carbohydrate conjugates, nucleosides, alkaloids and their derivatives, and pyridines and their derivatives. The resulting omics data underscored the significance of 23 core metabolic processes on the enhancement of drought tolerance or adaptation to drought in annual ryegrass. CONCLUSIONS The regulatory networks were inferred using MCoA and correlation analysis to reveal the relationships among the expression of transcripts, proteins, and metabolites that highlight the corresponding elements of these core metabolic pathways. Our results provide valuable insight into the molecular mechanisms of drought resistance, and represent a promising strategy toward the improvement of drought tolerance in annual ryegrass.
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Affiliation(s)
- Ling Pan
- Department of Grassland Science, College of Animal Science and Technology, Sichuan Agricultural University, Chengdu, China
| | - Chen Meng
- Chair of Proteomics and Bioanalytics, Technical University of Munich, 85354 Freising, Germany
| | - Jianping Wang
- Agronomy Department, University of Florida, Gainesville, USA
| | - Xiao Ma
- Department of Grassland Science, College of Animal Science and Technology, Sichuan Agricultural University, Chengdu, China
| | - Xiaomei Fan
- Vazyme Biotech Co., Ltd, Nanjing State Economy & Technology Development Zone, Red Maple Technology Industrial Park, Nanjing, China
| | - Zhongfu Yang
- Department of Grassland Science, College of Animal Science and Technology, Sichuan Agricultural University, Chengdu, China
| | - Meiliang Zhou
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Xinquan Zhang
- Department of Grassland Science, College of Animal Science and Technology, Sichuan Agricultural University, Chengdu, China
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Lintunen A, Mayr S, Salmon Y, Cochard H, Hölttä T. Drivers of apoplastic freezing in gymnosperm and angiosperm branches. Ecol Evol 2018; 8:333-343. [PMID: 29321875 PMCID: PMC5756836 DOI: 10.1002/ece3.3665] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Revised: 11/02/2017] [Accepted: 11/03/2017] [Indexed: 11/11/2022] Open
Abstract
It is not well understood what determines the degree of supercooling of apoplastic sap in trees, although it determines the number and duration of annual freeze-thaw cycles in a given environment. We studied the linkage between apoplastic ice nucleation temperature, tree water status, and conduit size. We used branches of 10 gymnosperms and 16 angiosperms collected from an arboretum in Helsinki (Finland) in winter and spring. Branches with lower relative water content froze at lower temperatures, and branch water content was lower in winter than in spring. A bench drying experiment with Picea abies confirmed that decreasing branch water potential decreases apoplastic ice nucleation temperature. The studied angiosperms froze on average 2.0 and 1.8°C closer to zero Celsius than the studied gymnosperms during winter and spring, respectively. This was caused by higher relative water content in angiosperms; when branches were saturated with water, apoplastic ice nucleation temperature of gymnosperms increased to slightly higher temperature than that of angiosperms. Apoplastic ice nucleation temperature in sampled branches was positively correlated with xylem conduit diameter as shown before, but saturating the branches removed the correlation. Decrease in ice nucleation temperature decreased the duration of freezing, which could have an effect on winter embolism formation via the time available for gas escape during ice propagation. The apoplastic ice nucleation temperature varied not only between branches but also within a branch between consecutive freeze-thaw cycles demonstrating the stochastic nature of ice nucleation.
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Affiliation(s)
- Anna Lintunen
- Department of Forest SciencesUniversity of HelsinkiHelsinkiFinland
- Department of PhysicsUniversity of HelsinkiHelsinkiFinland
| | - Stefan Mayr
- Institute of BotanyUniversity of InnsbruckInnsbruckAustria
| | - Yann Salmon
- Department of PhysicsUniversity of HelsinkiHelsinkiFinland
| | - Hervé Cochard
- University of Clermont‐AuvergneClermont‐FerrandFrance
| | - Teemu Hölttä
- Department of Forest SciencesUniversity of HelsinkiHelsinkiFinland
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Grossiord C, Sevanto S, Borrego I, Chan AM, Collins AD, Dickman LT, Hudson PJ, McBranch N, Michaletz ST, Pockman WT, Ryan M, Vilagrosa A, McDowell NG. Tree water dynamics in a drying and warming world. PLANT, CELL & ENVIRONMENT 2017; 40:1861-1873. [PMID: 28556263 DOI: 10.1111/pce.12991] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Revised: 05/02/2017] [Accepted: 05/09/2017] [Indexed: 05/16/2023]
Abstract
Disentangling the relative impacts of precipitation reduction and vapour pressure deficit (VPD) on plant water dynamics and determining whether acclimation may influence these patterns in the future is an important challenge. Here, we report sap flux density (FD ), stomatal conductance (Gs ), hydraulic conductivity (KL ) and xylem anatomy in piñon pine (Pinus edulis) and juniper (Juniperus monosperma) trees subjected to five years of precipitation reduction, atmospheric warming (elevated VPD) and their combined effects. No acclimation occurred under precipitation reduction: lower Gs and FD were found for both species compared to ambient conditions. Warming reduced the sensibility of stomata to VPD for both species but resulted in the maintenance of Gs and FD to ambient levels only for piñon. For juniper, reduced soil moisture under warming negated benefits of stomatal adjustments and resulted in reduced FD , Gs and KL . Although reduced stomatal sensitivity to VPD also occurred under combined stresses, reductions in Gs , FD and KL took place to similar levels as under single stresses for both species. Our results show that stomatal conductance adjustments to high VPD could minimize but not entirely prevent additive effects of warming and drying on water use and carbon acquisition of trees in semi-arid regions.
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Affiliation(s)
- Charlotte Grossiord
- Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - Sanna Sevanto
- Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - Isaac Borrego
- Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - Allison M Chan
- Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - Adam D Collins
- Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - Lee T Dickman
- Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - Patrick J Hudson
- Department of Biology, MSC03 202, University of New Mexico, Albuquerque, NM, 87131-0001, USA
| | - Natalie McBranch
- Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - Sean T Michaletz
- Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - William T Pockman
- Department of Biology, MSC03 202, University of New Mexico, Albuquerque, NM, 87131-0001, USA
| | - Max Ryan
- Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - Alberto Vilagrosa
- Fundación CEAM, Joint Research Unit University of Alicante - CEAM, Univ. Alicante, PO Box 99, 03080, Alicante, Spain
| | - Nate G McDowell
- Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, WA, 99352, USA
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20
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Sperling O, Secchi F, Godfrey J, Zwieniecki MA. Acclimation of Pistacia integerrima trees to frost in semi-arid environments depends on autumn's drought. PLANTA 2017; 245:671-679. [PMID: 27995314 DOI: 10.1007/s00425-016-2629-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2016] [Accepted: 11/28/2016] [Indexed: 06/06/2023]
Abstract
Main conclusion Cold acclimation is revealed through induced stem respiration during pre-winter frost of native Pistacia integerrima trees in continental semi-arid environments. Semi-arid environments challenge vegetation by simultaneous abiotic stresses. In this study, we examine the combined effects of water stress and frost on the physiology of Pistacia integerrima stems. This species is native to semi-arid environments where drought and frost frequently co-occur. We quantified carbohydrates and proline in P. integerrima stems responding to frost and experiencing water potentials between -0.2 and -1.8 MPa. We report that dehydrated trees (i.e., Ψstem <=-1 MPa) had more soluble sugars and proline than the well-watered trees (-0.2 MPa). The dehydrated trees also froze at lower temperatures and were less damaged by freezing. Interestingly, we observed a significant increase in stem CO2 efflux at near-freezing temperatures that could be linked to frost protection. This novel finding challenges current paradigm of plant respiration-kinetics which predicts, according to Arrhenius equation, lower respiration rates during frost. Our results support the notion that drought and frost are analogous stresses that can independently activate corresponding physiological processes in trees and amplify protection. This inevitable stress response 'collaboration' may be the key to understanding how non-dormant perennial plants survive the highly variable weather patterns of early winters in semi-arid environments.
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Affiliation(s)
- Or Sperling
- Department of Plant Sciences, UC Davis, Davis, CA, 95616, USA.
| | - Francesca Secchi
- Department of Agricultural, Forest and Food Sciences (DISAFA), University of Torino, Largo Paolo Braccini 2, 10095, Grugliasco (TO), Italy
| | - Jessie Godfrey
- Department of Plant Sciences, UC Davis, Davis, CA, 95616, USA
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21
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Kong RS, Henry HAL. Prior exposure to freezing stress enhances the survival and recovery of Poa pratensis exposed to severe drought. AMERICAN JOURNAL OF BOTANY 2016; 103:1890-1896. [PMID: 27803002 DOI: 10.3732/ajb.1600176] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Accepted: 09/23/2016] [Indexed: 06/06/2023]
Abstract
PREMISE OF THE STUDY Both freezing and drought cause cellular dehydration, and they elicit similar increases in protective compounds, which suggests that these stresses could potentially interact. We examined whether the physiological changes that occur in response to freezing in the fall and spring could affect subsequent survival and growth after summer drought. METHODS We froze Poa pratensis tillers in the late fall, early spring, or late spring at 0, -5, or -10°C for 3 d and then subjected them to no drought (-0.025 MPa), moderate drought (-0.140 MPa), or severe drought (-0.250 MPa) for 3 wk in the summer. We quantified survival and total biomass after a 3-wk recovery period, and we determined leaf soluble sugar concentrations before and then 0, 30, and 55 d after freezing. KEY RESULTS For survival and biomass, there were significant interactions between freezing and drought. Spring frozen tillers had the highest biomass and survival following severe drought, whereas fall freezing did not significantly increase the biomass of tillers following the severe drought. Increased drought tolerance after spring freezing did not appear to be associated with increased soluble sugar content, given that the freezing effects on leaf glucose, fructose, and sucrose content were absent 55 d post freezing. CONCLUSIONS Our results demonstrate that multiple stresses that occur over different seasons can interact; this interaction is highly relevant to herbaceous species in northern temperate regions that are experiencing more intense and frequent stress as a result of changes in snow cover and extreme climatic events.
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Affiliation(s)
- Ricky S Kong
- Department of Biology, University of Western Ontario, 1151 Richmond St. N., London, ON, Canada, N6A 5B7
| | - Hugh A L Henry
- Department of Biology, University of Western Ontario, 1151 Richmond St. N., London, ON, Canada, N6A 5B7
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22
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Drought increases the freezing resistance of high-elevation plants of the Central Chilean Andes. Oecologia 2016; 181:1011-23. [DOI: 10.1007/s00442-016-3622-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 03/25/2016] [Indexed: 11/24/2022]
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O’Keefe K, Nippert JB, Swemmer AM. Savanna Tree Seedlings are Physiologically Tolerant to Nighttime Freeze Events. FRONTIERS IN PLANT SCIENCE 2016; 7:46. [PMID: 26870065 PMCID: PMC4735699 DOI: 10.3389/fpls.2016.00046] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Accepted: 01/12/2016] [Indexed: 05/26/2023]
Abstract
Freeze events can be important disturbances in savanna ecosystems, yet the interactive effect of freezing with other environmental drivers on plant functioning is unknown. Here, we investigated physiological responses of South African tree seedlings to interactions of water availability and freezing temperatures. We grew widely distributed South African tree species (Colophospermum mopane, Combretum apiculatum, Acacia nigrescens, and Cassia abbreviata) under well-watered and water-limited conditions and exposed individuals to nighttime freeze events. Of the four species studied here, C. mopane was the most tolerant of lower water availability. However, all species were similarly tolerant to nighttime freezing and recovered within one week following the last freezing event. We also show that water limitation somewhat increased freezing tolerance in one of the species (C. mopane). Therefore, water limitation, but not freezing temperatures, may restrict the distribution of these species, although the interactions of these stressors may have species-specific impacts on plant physiology. Ultimately, we show that unique physiologies can exist among dominant species within communities and that combined stresses may play a currently unidentified role in driving the function of certain species within southern Africa.
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25
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He Y, D'Odorico P, De Wekker SFJ. The role of vegetation-microclimate feedback in promoting shrub encroachment in the northern Chihuahuan desert. GLOBAL CHANGE BIOLOGY 2015; 21:2141-2154. [PMID: 25581578 DOI: 10.1111/gcb.12856] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Revised: 10/17/2014] [Accepted: 11/04/2014] [Indexed: 06/04/2023]
Abstract
Many arid and semi-arid landscapes around the world are affected by a shift from grassland to shrubland vegetation, presumably induced by climate warming, increasing atmospheric CO2 concentrations, and/or changing land use. This major change in vegetation cover is likely sustained by positive feedbacks with the physical environment. Recent research has focused on a feedback with microclimate, whereby cold intolerant shrubs increase the minimum nocturnal temperatures in their surroundings. Despite the rich literature on the impact of land cover change on local climate conditions, changes in microclimate resulting from shrub expansion into desert grasslands have remained poorly investigated. It is unclear to what extent such a feedback can affect the maximum extent of shrub expansion and the configuration of a stable encroachment front. Here, we focus on the case of the northern Chihuahuan desert, where creosotebush (Larrea tridentata) has been replacing grasslands over the past 100-150 years. We use a process-based coupled atmosphere-vegetation model to investigate the role of this feedback in sustaining shrub encroachment in the region. Simulations indicate that the feedback allows juvenile shrubs to establish in the grassland during average years and, once established, reduce their vulnerability to freeze-induced mortality by creating a warmer microclimate. Such a feedback is crucial in extreme cold winters as it may reduce shrub mortality. We identify the existence of a critical zone in the surroundings of the encroachment front, in which vegetation dynamics are bistable: in this zone, vegetation can be stable both as grassland and as shrubland. The existence of these alternative stable states explains why in most cases the shift from grass to shrub cover is found to be abrupt and often difficult to revert.
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Affiliation(s)
- Yufei He
- Department of Environmental Sciences, University of Virginia, 291 McCormick Rd, Charlottesville, VA, 22904-4123, USA
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Butterfield BJ. Environmental filtering increases in intensity at both ends of climatic gradients, though driven by different factors, across woody vegetation types of the southwest USA. OIKOS 2015. [DOI: 10.1111/oik.02311] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Bradley J. Butterfield
- Merriam-Powell Center for Environmental Research and Dept of Biological Sciences; Northern Arizona Univ.; PO Box 6077, Flagstaff AZ 86011 USA
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Medeiros JS, Ward JK. Increasing atmospheric [CO2] from glacial to future concentrations affects drought tolerance via impacts on leaves, xylem and their integrated function. THE NEW PHYTOLOGIST 2013; 199:738-48. [PMID: 23668237 PMCID: PMC3710516 DOI: 10.1111/nph.12318] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2013] [Accepted: 04/07/2013] [Indexed: 05/09/2023]
Abstract
Changes in atmospheric carbon dioxide concentration ([CO2]) affect plant carbon/water tradeoffs, with implications for drought tolerance. Leaf-level studies often indicate that drought tolerance may increase with rising [CO2], but integrated leaf and xylem responses are not well understood in this respect. In addition, the influence of the low [CO2] of the last glacial period on drought tolerance and xylem properties is not well understood. We investigated the interactive effects of a broad range of [CO2] and plant water potentials on leaf function, xylem structure and function and the integration of leaf and xylem function in Phaseolus vulgaris. Elevated [CO2] decreased vessel implosion strength, reduced conduit-specific hydraulic conductance, and compromised leaf-specific xylem hydraulic conductance under moderate drought. By contrast, at glacial [CO2], transpiration was maintained under moderate drought via greater conduit-specific and leaf-specific hydraulic conductance in association with increased vessel implosion strength. Our study involving the integration of leaf and xylem responses suggests that increasing [CO2] does not improve drought tolerance. We show that, under glacial conditions, changes in leaf and xylem properties could increase drought tolerance, while under future conditions, greater productivity may only occur when higher water use can be accommodated.
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28
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Preston JC, Sandve SR. Adaptation to seasonality and the winter freeze. FRONTIERS IN PLANT SCIENCE 2013; 4:167. [PMID: 23761798 PMCID: PMC3669742 DOI: 10.3389/fpls.2013.00167] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Accepted: 05/13/2013] [Indexed: 05/20/2023]
Abstract
Flowering plants initially diversified during the Mesozoic era at least 140 million years ago in regions of the world where temperate seasonal environments were not encountered. Since then several cooling events resulted in the contraction of warm and wet environments and the establishment of novel temperate zones in both hemispheres. In response, less than half of modern angiosperm families have members that evolved specific adaptations to cold seasonal climates, including cold acclimation, freezing tolerance, endodormancy, and vernalization responsiveness. Despite compelling evidence for multiple independent origins, the level of genetic constraint on the evolution of adaptations to seasonal cold is not well understood. However, the recent increase in molecular genetic studies examining the response of model and crop species to seasonal cold offers new insight into the evolutionary lability of these traits. This insight has major implications for our understanding of complex trait evolution, and the potential role of local adaptation in response to past and future climate change. In this review, we discuss the biochemical, morphological, and developmental basis of adaptations to seasonal cold, and synthesize recent literature on the genetic basis of these traits in a phylogenomic context. We find evidence for multiple genetic links between distinct physiological responses to cold, possibly reinforcing the coordinated expression of these traits. Furthermore, repeated recruitment of the same or similar ancestral pathways suggests that land plants might be somewhat pre-adapted to dealing with temperature stress, perhaps making inducible cold traits relatively easy to evolve.
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Affiliation(s)
- Jill C. Preston
- Department of Plant Biology, University of VermontBurlington, VT, USA
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Consequences of Cool-Season Drought-Induced Plant Mortality to Chihuahuan Desert Grassland Ecosystem and Soil Respiration Dynamics. Ecosystems 2013. [DOI: 10.1007/s10021-013-9675-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Effects of experimental rainfall manipulations on Chihuahuan Desert grassland and shrubland plant communities. Oecologia 2012; 172:1117-27. [PMID: 23263528 DOI: 10.1007/s00442-012-2552-0] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2011] [Accepted: 11/26/2012] [Indexed: 10/27/2022]
Abstract
Aridland ecosystems are predicted to be responsive to both increases and decreases in precipitation. In addition, chronic droughts may contribute to encroachment of native C3 shrubs into C4-dominated grasslands. We conducted a long-term rainfall manipulation experiment in native grassland, shrubland and the grass-shrub ecotone in the northern Chihuahuan Desert, USA. We evaluated the effects of 5 years of experimental drought and 4 years of water addition on plant community structure and dynamics. We assessed the effects of altered rainfall regimes on the abundance of dominant species as well as on species richness and subdominant grasses, forbs and shrubs. Nonmetric multidimensional scaling and MANOVA were used to quantify changes in species composition in response to chronic addition or reduction of rainfall. We found that drought consistently and strongly decreased cover of Bouteloua eriopoda, the dominant C4 grass in this system, whereas water addition slightly increased cover, with little variation between years. In contrast, neither chronic drought nor increased rainfall had consistent effects on the cover of Larrea tridentata, the dominant C3 shrub. Species richness declined in shrub-dominated vegetation in response to drought whereas richness increased or was unaffected by water addition or drought in mixed- and grass-dominated vegetation. Cover of subdominant shrubs, grasses and forbs changed significantly over time, primarily in response to interannual rainfall variability more so than to our experimental rainfall treatments. Nevertheless, drought and water addition shifted the species composition of plant communities in all three vegetation types. Overall, we found that B. eriopoda responded strongly to drought and less so to irrigation, whereas L. tridentata showed limited response to either treatment. The strong decline in grass cover and the resistance of shrub cover to rainfall reduction suggest that chronic drought may be a key factor promoting shrub dominance during encroachment into desert grassland.
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Medeiros JS, Marshall DL, Maherali H, Pockman WT. Variation in seedling freezing response is associated with climate in Larrea. Oecologia 2012; 169:73-84. [PMID: 22068319 PMCID: PMC3711214 DOI: 10.1007/s00442-011-2181-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Accepted: 10/20/2011] [Indexed: 11/30/2022]
Abstract
Variation in freezing severity is hypothesized to have influenced the distribution and evolution of the warm desert evergreen genus Larrea. If this hypothesis is correct, performance and survival of species and populations should vary predictably along gradients of freezing severity. If freezing environment changes in the future, the ability of Larrea to adapt will depend on the structure of variation for freezing resistance within populations. To test whether freezing responses vary among and within Larrea populations, we grew maternal families of seedlings from high and low latitude L. divaricata and high latitude L. tridentata populations in a common garden. We measured survival, projected plant area and dark-adapted chlorophyll fluorescence (F (v) /F (m)) before and after cold acclimation and for 2 weeks following a single freeze. We detected significant variation in freezing resistance among species and populations. Maternal family lines differed significantly in their responses to cold acclimation and/or freezing for two out of the three populations: among L. tridentata maternal families and among low latitude L. divaricata maternal families. There were no significant differences across maternal families of high latitude L. divaricata. Our results indicate that increased freezing resistance in high latitude populations likely facilitated historical population expansion of both species into colder climates, but this may have occurred to a greater extent for L. tridentata than for L. divaricata. Differences in the structure of variation for cold acclimation and freezing responses among populations suggest potential differences in their ability to evolve in response to future changes in freezing severity.
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Affiliation(s)
- Juliana S Medeiros
- Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS 66045, USA.
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