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Soininen EM, Neby M. Small rodent population cycles and plants - after 70 years, where do we go? Biol Rev Camb Philos Soc 2024; 99:265-294. [PMID: 37827522 DOI: 10.1111/brv.13021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Revised: 09/22/2023] [Accepted: 09/25/2023] [Indexed: 10/14/2023]
Abstract
Small rodent population cycles characterise northern ecosystems, and the cause of these cycles has been a long-lasting central topic in ecology, with trophic interactions currently considered the most plausible cause. While some researchers have rejected plant-herbivore interactions as a cause of rodent cycles, others have continued to research their potential roles. Here, we present an overview of whether plants can cause rodent population cycles, dividing this idea into four different hypotheses with different pathways of plant impacts and related assumptions. Our systematic review of the existing literature identified 238 studies from 150 publications. This evidence base covered studies from the temperate biome to the tundra, but the studies were scattered across study systems and only a few specific topics were addressed in a replicated manner. Quantitative effects of rodents on vegetation was the best studied topic, and our evidence base suggests such that such effects may be most pronounced in winter. However, the regrowth of vegetation appears to take place too rapidly to maintain low rodent population densities over several years. The lack of studies prevented assessment of time lags in the qualitative responses of vegetation to rodent herbivory. We conclude that the literature is currently insufficient to discard with confidence any of the four potential hypotheses for plant-rodent cycles discussed herein. While new methods allow analyses of plant quality across more herbivore-relevant spatial scales than previously possible, we argue that the best way forward to rejecting any of the rodent-plant hypotheses is testing specific predictions of dietary variation. Indeed, all identified hypotheses make explicit assumptions on how rodent diet taxonomic composition and quality will change across the cycle. Passing this bottleneck could help pinpoint where, when, and how plant-herbivore interactions have - or do not have - plausible effects on rodent population dynamics.
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Affiliation(s)
- Eeva M Soininen
- Department of Arctic and Marine Biology, UiT-The Arctic University of Norway, Postboks 6050 Langnes, Tromsø, 9037, Norway
| | - Magne Neby
- Faculty of Applied Ecology, Agricultural Sciences and Biotechnology, Høyvangvegen 40, Ridabu, 2322, Norway
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2
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Thorne SJ, Maathuis FJM, Hartley SE. Induction of silicon defences in wheat landraces is local, not systemic, and driven by mobilization of soluble silicon to damaged leaves. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:5363-5373. [PMID: 37314063 DOI: 10.1093/jxb/erad224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Accepted: 06/13/2023] [Indexed: 06/15/2023]
Abstract
In response to herbivory, many grasses, including crops such as wheat, accumulate significant levels of silicon (Si) as an antiherbivore defence. Damage-induced increases in Si can be localized in damaged leaves or be more systemic, but the mechanisms leading to these differences in Si distribution remain untested. Ten genetically diverse wheat landraces (Triticum aestivum) were used to assess genotypic variation in Si induction in response to mechanical damage and how this was affected by exogenous Si supply. Total and soluble Si levels were measured in damaged and undamaged leaves as well as in the phloem to test how Si was allocated to different parts of the plant after damage. Localized, but not systemic, induction of Si defences occurred, and was more pronounced when plants had supplemental Si. Damaged plants had significant increases in Si concentration in their damaged leaves, while the Si concentration in undamaged leaves decreased, such that there was no difference in the average Si concentration of damaged and undamaged plants. The increased Si in damaged leaves was due to the redirection of soluble Si, present in the phloem, from undamaged to damaged plant parts, potentially a more cost-effective defence mechanism for plants than increased Si uptake.
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Affiliation(s)
- Sarah J Thorne
- Plants, Photosynthesis, and Soil, School of Biosciences, University of Sheffield, Sheffield, S10 2TN, UK
| | | | - Susan E Hartley
- Plants, Photosynthesis, and Soil, School of Biosciences, University of Sheffield, Sheffield, S10 2TN, UK
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3
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Borowski Z, Zub K, Sulwiński M, Suska‐Malawska M, Konarzewski M. Plant-herbivore interactions: Combined effect of groundwater level, root vole grazing, and sedge silicification. Ecol Evol 2021; 11:16047-16054. [PMID: 34824810 PMCID: PMC8601873 DOI: 10.1002/ece3.8275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 08/25/2021] [Accepted: 10/12/2021] [Indexed: 11/21/2022] Open
Abstract
Accumulation of silica (Si) by plants can be driven by (1) herbivory pressure (and therefore plant-herbivore interactions), (2) geohydrological cycles, or (3) a combination of (1) and (2), with (1-3) possibly affecting Si concentration with a 1-year delay.To identify the relative significance of (1-3), we analyzed the concentration of Si in fibrous tussock sedge (Carex appropinquata), the population density of the root vole (Microtus oeconomus), and the groundwater level, over 11 years.The largest influence of autumn Si concentration in leaves (Sileaf) was on the level of the current-year groundwater table, which was positive and accounted for 13.3% of its variance. The previous year's vole population density was weakly positively correlated with Sileaf, and it alone explained 9.5% of its variance.The only variable found to have a positive, significant effect on autumn Si concentration in rhizomes (Sirhiz) was the current-year spring water level, explaining as much as 60.9% of its variance.We conclude that the changes in Si concentration in fibrous tussock sedge are predominantly driven by hydrology, with vole population dynamics being secondary.Our results provide only partial support for the existence of plant-herbivore interactions, as we did not detect the significant effects of Si tussock concentration on the vole density dynamics. This was mainly due to the low level of silicification of sedges, which was insufficient to impinge herbivores.Future studies on plant-herbivore interactions should therefore aim at disentangling whether anti-herbivore protection is dependent on threshold values of herbivore population dynamics. Furthermore, studies on Si accumulation should focus on the effect of water-mediated Si availability.
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Affiliation(s)
| | - Karol Zub
- Mammal Research Institute Polish Academy of SciencesBiałowieżaPoland
| | - Marcin Sulwiński
- Faculty of Biology, Biological and Chemical Research CentreWarsaw UniversityWarsawPoland
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4
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Petit Bon M, Böhner H, BrÅthen KA, Ravolainen VT, Jónsdóttir IS. Variable responses of carbon and nitrogen contents in vegetation and soil to herbivory and warming in high‐Arctic tundra. Ecosphere 2021. [DOI: 10.1002/ecs2.3746] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Matteo Petit Bon
- Department of Arctic Biology University Centre in Svalbard (UNIS) PO Box 156 N‐9171 Longyearbyen Norway
- Department of Arctic and Marine Biology Faculty of Biosciences, Fisheries, and Economics Arctic University of Norway (UiT) N‐9037 Tromsø Norway
| | - Hanna Böhner
- Department of Arctic Biology University Centre in Svalbard (UNIS) PO Box 156 N‐9171 Longyearbyen Norway
- Department of Arctic and Marine Biology Faculty of Biosciences, Fisheries, and Economics Arctic University of Norway (UiT) N‐9037 Tromsø Norway
| | - Kari Anne BrÅthen
- Department of Arctic and Marine Biology Faculty of Biosciences, Fisheries, and Economics Arctic University of Norway (UiT) N‐9037 Tromsø Norway
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5
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Mundada PS, Ahire ML, Umdale SD, Barmukh RB, Nikam TD, Pable AA, Deshmukh RK, Barvkar VT. Characterization of influx and efflux silicon transporters and understanding their role in the osmotic stress tolerance in finger millet (Eleusine coracana (L.) Gaertn.). PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2021; 162:677-689. [PMID: 33780741 DOI: 10.1016/j.plaphy.2021.03.033] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 03/16/2021] [Indexed: 06/12/2023]
Abstract
Over the last decade, silicon (Si) has been widely accepted as a beneficial element for plant growth. The advantages plant derives from the Si are primarily based on the uptake and transport mechanisms. In the present study, the Si uptake regime was studied in finger millet (Eleusine coracana (L). Gaertn.) under controlled and stress conditions. The finger millet can efficiently uptake Si and accumulate it by more than 1% of dry weight in the leaf tissues, thus categorized as a Si accumulator. Subsequent evaluation with the single root assay revealed a three-fold higher Si uptake under osmatic stress than control. These results suggest that Si alleviated the PEG-induced stress by regulating the levels of osmolytes and antioxidant enzymes. Further, to understand the molecular mechanism involved in Si uptake, the Si influx (EcoLsi1 and EcoLsi6) and efflux transporters (EcoLsi2 and EcoLsi3) were identified and characterized. The comparative phylogenomic analysis of the influx transporter EcoLsi1 with other monocots revealed conserved features like aromatic/arginine (Ar/R) selectivity filters and pore morphology. Similarly, Si efflux transporter EcoLsi3 is highly homologous to other annotated efflux transporters. The transcriptome data revealed that the expression of both influx and efflux Si transporters was elevated due to Si supplementation under stress conditions. These findings suggest that stress elevates Si uptake in finger millet, and its transport is also regulated by the Si transporters. The present study will be helpful to better explore Si derived benefits in finger millet.
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Affiliation(s)
- Pankaj S Mundada
- Department of Botany, Savitribai Phule Pune University, Pune, 411 007, Maharashtra, India; Department of Biotechnology, Yashavantrao Chavan Institute of Science, Satara, 415 001, Maharashtra, India
| | - Mahendra L Ahire
- Department of Botany, Yashavantrao Chavan Institute of Science, Satara, 415 001, Maharashtra, India
| | - Suraj D Umdale
- Department of Botany, Jaysingpur College, Jaysingpur, 416 101, Maharashtra, India
| | - Rajkumar B Barmukh
- Department of Botany, Modern College of Arts, Science and Commerce, Pune, 411 005, Maharashtra, India
| | - Tukaram D Nikam
- Department of Botany, Savitribai Phule Pune University, Pune, 411 007, Maharashtra, India
| | - Anupama A Pable
- Department of Microbiology, Savitribai Phule Pune University, Pune, 411 007, Maharashtra, India
| | - Rupesh K Deshmukh
- National Agri-Food Biotechnology Institute, Mohali, 140 306, Punjab, India
| | - Vitthal T Barvkar
- Department of Botany, Savitribai Phule Pune University, Pune, 411 007, Maharashtra, India.
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Thorne SJ, Hartley SE, Maathuis FJM. The Effect of Silicon on Osmotic and Drought Stress Tolerance in Wheat Landraces. PLANTS (BASEL, SWITZERLAND) 2021; 10:814. [PMID: 33924159 PMCID: PMC8074377 DOI: 10.3390/plants10040814] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 04/16/2021] [Accepted: 04/19/2021] [Indexed: 12/13/2022]
Abstract
Drought stress reduces annual global wheat yields by 20%. Silicon (Si) fertilisation has been proposed to improve plant drought stress tolerance. However, it is currently unknown if and how Si affects different wheat landraces, especially with respect to their innate Si accumulation properties. In this study, significant and consistent differences in Si accumulation between landraces were identified, allowing for the classification of high Si accumulators and low Si accumulators. Landraces from the two accumulation groups were then used to investigate the effect of Si during osmotic and drought stress. Si was found to improve growth marginally in high Si accumulators during osmotic stress. However, no significant effect of Si on growth during drought stress was found. It was further found that osmotic stress decreased Si accumulation for all landraces whereas drought increased it. Overall, these results suggest that the beneficial effect of Si commonly reported in similar studies is not universal and that the application of Si fertiliser as a solution to agricultural drought stress requires detailed understanding of genotype-specific responses to Si.
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Affiliation(s)
- Sarah J. Thorne
- Department of Biology, University of York, York YO10 5DD, UK;
| | - Susan E. Hartley
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK;
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Katz O, Puppe D, Kaczorek D, Prakash NB, Schaller J. Silicon in the Soil-Plant Continuum: Intricate Feedback Mechanisms within Ecosystems. PLANTS (BASEL, SWITZERLAND) 2021; 10:652. [PMID: 33808069 PMCID: PMC8066056 DOI: 10.3390/plants10040652] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/14/2021] [Revised: 03/22/2021] [Accepted: 03/26/2021] [Indexed: 11/28/2022]
Abstract
Plants' ability to take up silicon from the soil, accumulate it within their tissues and then reincorporate it into the soil through litter creates an intricate network of feedback mechanisms in ecosystems. Here, we provide a concise review of silicon's roles in soil chemistry and physics and in plant physiology and ecology, focusing on the processes that form these feedback mechanisms. Through this review and analysis, we demonstrate how this feedback network drives ecosystem processes and affects ecosystem functioning. Consequently, we show that Si uptake and accumulation by plants is involved in several ecosystem services like soil appropriation, biomass supply, and carbon sequestration. Considering the demand for food of an increasing global population and the challenges of climate change, a detailed understanding of the underlying processes of these ecosystem services is of prime importance. Silicon and its role in ecosystem functioning and services thus should be the main focus of future research.
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Affiliation(s)
- Ofir Katz
- Dead Sea and Arava Science Center, Mt. Masada, Tamar Regional Council, 86910 Tamar, Israel
- Eilat Campus, Ben-Gurion University of the Negev, Hatmarim Blv, 8855630 Eilat, Israel
| | - Daniel Puppe
- Leibniz Centre for Agricultural Landscape Research (ZALF), 15374 Müncheberg, Germany; (D.P.); (D.K.); (J.S.)
| | - Danuta Kaczorek
- Leibniz Centre for Agricultural Landscape Research (ZALF), 15374 Müncheberg, Germany; (D.P.); (D.K.); (J.S.)
- Department of Soil Environment Sciences, Warsaw University of Life Sciences (SGGW), 02776 Warsaw, Poland
| | - Nagabovanalli B. Prakash
- Department of Soil Science and Agricultural Chemistry, University of Agricultural Sciences, GKVK, Bangalore 560065, India;
| | - Jörg Schaller
- Leibniz Centre for Agricultural Landscape Research (ZALF), 15374 Müncheberg, Germany; (D.P.); (D.K.); (J.S.)
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8
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Singh A, Kumar A, Hartley S, Singh IK. Silicon: its ameliorative effect on plant defense against herbivory. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:6730-6743. [PMID: 32591824 DOI: 10.1093/jxb/eraa300] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Accepted: 06/19/2020] [Indexed: 05/06/2023]
Abstract
Plants protect themselves against pest attack utilizing both direct and indirect modes of defense. The direct mode of defense includes morphological, biochemical, and molecular barriers that affect feeding, growth, and survival of herbivores whereas the indirect mode of defense includes release of a blend of volatiles that attract natural enemies of the pests. Both of these strategies adopted by plants are reinforced if the plants are supplied with one of the most abundant metalloids, silicon (Si). Plants absorb Si as silicic acid (Si(OH)4) and accumulate it as phytoliths, which strengthens their physical defense. This deposition of Si in plant tissue is up-regulated upon pest attack. Further, Si deposited in the apoplast, suppresses pest effector molecules. Additionally, Si up-regulates the expression of defense-related genes and proteins and their activity and enhances the accumulation of secondary metabolites, boosting induced molecular and biochemical defenses. Moreover, Si plays a crucial role in phytohormone-mediated direct and indirect defense mechanisms. It is also involved in the reduction of harmful effects of oxidative stress resulting from herbivory by accelerating the scavenging process. Despite increasing evidence of its multiple roles in defense against pests, the practical implications of Si for crop protection have received less attention. Here, we highlight recent developments in Si-mediated improved plant resistance against pests and its significance for future use in crop improvement.
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Affiliation(s)
- Archana Singh
- Department of Botany, Hansraj College, University of Delhi, Delhi, India
| | - Amit Kumar
- Department of Botany, Hansraj College, University of Delhi, Delhi, India
| | - Susan Hartley
- Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield, UK
| | - Indrakant Kumar Singh
- Molecular Biology Research Lab, Department of Zoology, Deshbandhu College, University of Delhi, Kalkaji, New Delhi, India
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9
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Brightly WH, Hartley SE, Osborne CP, Simpson KJ, Strömberg CAE. High silicon concentrations in grasses are linked to environmental conditions and not associated with C 4 photosynthesis. GLOBAL CHANGE BIOLOGY 2020; 26:7128-7143. [PMID: 32897634 DOI: 10.1111/gcb.15343] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 08/03/2020] [Indexed: 06/11/2023]
Abstract
The uptake and deposition of silicon (Si) as silica phytoliths is common among land plants and is associated with a variety of functions. Among these, herbivore defense has received significant attention, particularly with regard to grasses and grasslands. Grasses are well known for their high silica content, a trait which has important implications ranging from defense to global Si cycling. Here, we test the classic hypothesis that C4 grasses evolved stronger mechanical defenses than C3 grasses through increased phytolith deposition, in response to extensive ungulate herbivory ("C4 -grazer hypothesis"). Despite mixed support, this hypothesis has received broad attention, even outside the realm of plant biology. Because C3 and C4 grasses typically dominate in different climates, with the latter more abundant in hot, dry regions, we also investigated the effects of water availability and temperature on Si deposition. We compiled a large dataset of grasses grown under controlled environmental conditions. Using phylogenetically informed generalized linear mixed models and character evolution models, we evaluated whether photosynthetic pathway or growth condition influenced Si concentration. We found that C4 grasses did not show consistently elevated Si concentrations compared with C3 grasses. High temperature treatments were associated with increased concentration, especially in taxa adapted to warm regions. Although the effect was less pronounced, reduced water treatment also promoted silica deposition, with slightly stronger response in dry habitat species. The evidence presented here rejects the "C4 -grazer hypothesis." Instead, we propose that the tendency for C4 grasses to outcompete C3 species under hot, dry conditions explains previous observations supporting this hypothesis. These findings also suggest a mechanism via which anthropogenic climate change may influence silica deposition in grasses and, by extension, alter the important ecological and geochemical processes it affects.
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Affiliation(s)
- William H Brightly
- Department of Biology and the Burke Museum of Natural History and Culture, University of Washington, Seattle, WA, USA
| | - Sue E Hartley
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK
| | - Colin P Osborne
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK
| | - Kimberley J Simpson
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK
| | - Caroline A E Strömberg
- Department of Biology and the Burke Museum of Natural History and Culture, University of Washington, Seattle, WA, USA
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10
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Wei GW, Sun XS, Chen YH, Luo FL, Yu FH. Growth and reproductive responses of Polygonum hydropiper populations to elevational difference associated with flooding. Glob Ecol Conserv 2020. [DOI: 10.1016/j.gecco.2020.e01156] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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11
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Croy JR, Meyerson LA, Allen WJ, Bhattarai GP, Cronin JT. Lineage and latitudinal variation inPhragmites australistolerance to herbivory: implications for invasion success. OIKOS 2020. [DOI: 10.1111/oik.07260] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Jordan R. Croy
- Dept of Biological Sciences, Louisiana State Univ. Baton Rouge LA 70803 USA
- Dept of Ecology and Evolutionary Biology, Univ. of California Irvine CA 92697 USA
| | - Laura A. Meyerson
- Dept of Natural Resource Sciences, Univ. of Rhode Island Kingston RI USA
| | - Warwick J. Allen
- Dept of Biological Sciences, Louisiana State Univ. Baton Rouge LA 70803 USA
- The Bio‐Protection Research Centre, School of Biological Sciences, Univ. of Canterbury Christchurch New Zealand
| | - Ganesh P. Bhattarai
- Dept of Biological Sciences, Louisiana State Univ. Baton Rouge LA 70803 USA
- Dept of Entomology, Kansas State Univ. Manhattan KS USA
| | - James T. Cronin
- Dept of Biological Sciences, Louisiana State Univ. Baton Rouge LA 70803 USA
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12
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Petit Bon M, Gunnarsdotter Inga K, Jónsdóttir IS, Utsi TA, Soininen EM, Bråthen KA. Interactions between winter and summer herbivory affect spatial and temporal plant nutrient dynamics in tundra grassland communities. OIKOS 2020. [DOI: 10.1111/oik.07074] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Matteo Petit Bon
- Dept of Arctic Biology, Univ. Centre in Svalbard (UNIS) PO Box 156 NO‐9171 Longyearbyen Norway
- Dept of Arctic and Marine Biology, Faculty of Biosciences, Fisheries, and Economics, Arctic Univ. of Norway (UiT) Tromsø Norway
| | - Katarina Gunnarsdotter Inga
- Dept of Arctic and Marine Biology, Faculty of Biosciences, Fisheries, and Economics, Arctic Univ. of Norway (UiT) Tromsø Norway
| | | | - Tove Aagnes Utsi
- Dept of Arctic and Marine Biology, Faculty of Biosciences, Fisheries, and Economics, Arctic Univ. of Norway (UiT) Tromsø Norway
| | - Eeva Marjatta Soininen
- Dept of Arctic and Marine Biology, Faculty of Biosciences, Fisheries, and Economics, Arctic Univ. of Norway (UiT) Tromsø Norway
| | - Kari Anne Bråthen
- Dept of Arctic and Marine Biology, Faculty of Biosciences, Fisheries, and Economics, Arctic Univ. of Norway (UiT) Tromsø Norway
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Quigley KM, Griffith DM, Donati GL, Anderson TM. Soil nutrients and precipitation are major drivers of global patterns of grass leaf silicification. Ecology 2020; 101:e03006. [PMID: 32020594 PMCID: PMC7317429 DOI: 10.1002/ecy.3006] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Revised: 11/26/2019] [Accepted: 12/20/2019] [Indexed: 11/23/2022]
Abstract
Grasses accumulate high concentrations of silicon (Si) in their tissues, with potential benefits including herbivore defense, improved water balance, and reduced leaf construction costs. Although Si is one of the most widely varying leaf constituents among individuals, species, and ecosystems, the environmental forces driving this variation remain elusive and understudied. To understand relationships between environmental factors and grass Si accumulation better, we analyzed foliar chemistry of grasses from 17 globally distributed sites where nutrient inputs and grazing were manipulated. These sites span natural gradients in temperature, precipitation, and underlying soil properties, which allowed us to assess the relative importance of soil moisture and nutrients across variation in climate. Foliar Si concentration did not respond to large mammalian grazer exclusion, but significant variation in herbivore abundance among sites may have precluded the observation of defoliation effects at these sites. However, nutrient addition consistently reduced leaf Si, especially at sites with low soil nitrogen prior to nutrient addition. Additionally, a leaf‐level trade‐off between Si and carbon (C) existed that was stronger at arid sites than mesic sites. Our results suggest soil nutrient limitation favors investment in Si over C‐based leaf construction, and that fixing C is especially costly relative to assimilating Si when water is limiting. Our results demonstrate the importance of soil nutrients and precipitation as key drivers of global grass silicification patterns.
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Affiliation(s)
- Kathleen M Quigley
- Department of Biology, Wake Forest University, Winston-Salem, North Carolina, 27109, USA
| | - Daniel M Griffith
- Department of Biology, Wake Forest University, Winston-Salem, North Carolina, 27109, USA
| | - George L Donati
- Department of Chemistry, Wake Forest University, Winston-Salem, North Carolina, 27109, USA
| | - T Michael Anderson
- Department of Biology, Wake Forest University, Winston-Salem, North Carolina, 27109, USA
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14
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Silicon and Plant-Animal Interactions: Towards an Evolutionary Framework. PLANTS 2020; 9:plants9040430. [PMID: 32244583 PMCID: PMC7238073 DOI: 10.3390/plants9040430] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 03/19/2020] [Accepted: 03/20/2020] [Indexed: 12/16/2022]
Abstract
Herbivory is fundamental in ecology, being a major driver of ecosystem structure and functioning. Plant Si and phytoliths play a significant antiherbivory role, the understanding of which and of its evolutionary context will increase our understanding of this phenomenon, its origins, and its significance for past, extant, and future ecosystems. To achieve this goal, we need a superdisciplinary evolutionary framework connecting the role of Si in plant–herbivore interactions, in global processes, and in plant and herbivore evolution. To do this properly, we should acknowledge and incorporate into our work some basic facts that are too often overlooked. First, there is great taxonomic variance both in plant Si contents, forms, and roles, but also in herbivore responses, dietary preferences, and in fossil evidence. Second, species and their traits, as well as whole ecosystems, should be seen in the context of their entire evolutionary history and may therefore reflect not only adaptations to extant selective factors but also anachronistic traits. Third, evolutionary history and evolutionary transitions are complex, resulting in true and apparent asynchronisms. Fourth, evolution and ecology are multiscalar, in which various phenomena and processes act at various scales. Taking these issues into consideration will improve our ability to develop this needed theoretical framework and will bring us closer to gaining a more complete understanding of one of the most exciting and elusive phenomena in plant biology and ecology.
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15
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Ruffino L, Hartley SE, DeGabriel JL, Lambin X. Population-level manipulations of field vole densities induce subsequent changes in plant quality but no impacts on vole demography. Ecol Evol 2018; 8:7752-7762. [PMID: 30250660 PMCID: PMC6145023 DOI: 10.1002/ece3.4204] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Revised: 03/13/2018] [Accepted: 04/19/2018] [Indexed: 11/06/2022] Open
Abstract
Grazing-induced changes in plant quality have been suggested to drive the negative delayed density dependence exhibited by many herbivore species, but little field evidence exists to support this hypothesis. We tested a key premise of the hypothesis that reciprocal feedback between vole grazing pressure and the induction of anti-herbivore silicon defenses in grasses drives observed population cycles in a large-scale field experiment in northern England. We repeatedly reduced population densities of field voles (Microtus agrestis) on replicated 1-ha grassland plots at Kielder Forest, northern England, over a period of 1 year. Subsequently, we tested for the impact of past density on vole life history traits in spring, and whether these effects were driven by induced silicon defenses in the voles' major over-winter food, the grass Deschampsia caespitosa. After several months of density manipulation, leaf silicon concentrations diverged and averaged 22% lower on sites where vole density had been reduced, but this difference did not persist beyond the period of the density manipulations. There were no significant effects of our density manipulations on vole body mass, spring population growth rate, or mean date for the onset of spring reproduction the following year. These findings show that grazing by field voles does induce increased silicon defenses in grasses at a landscape scale. However, at the vole densities encountered, levels of plant damage appear to be below those needed to induce changes in silicon levels large and persistent enough to affect vole performance, confirming the threshold effects we have previously observed in laboratory-based studies. Our findings do not support the plant quality hypothesis for observed vole population cycles in northern England, at least over the range of vole densities that now prevail here.
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Affiliation(s)
- Lise Ruffino
- School of Biological SciencesUniversity of AberdeenAberdeenUK
| | | | - Jane L. DeGabriel
- School of Biological SciencesUniversity of AberdeenAberdeenUK
- NSW Office of Environment and HeritageSydneyNSWAustralia
| | - Xavier Lambin
- School of Biological SciencesUniversity of AberdeenAberdeenUK
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16
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Soininen EM, Hamel S, Yoccoz NG. Importance of study design and robust analyses in ecology – what is the evidence for silica–vole interactions? Funct Ecol 2017. [DOI: 10.1111/1365-2435.12830] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | - Sandra Hamel
- UiT ‐ The Arctic University of Norway NO‐9037 Tromsø Norway
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17
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McLarnon E, McQueen-Mason S, Lenk I, Hartley SE. Evidence for Active Uptake and Deposition of Si-based Defenses in Tall Fescue. FRONTIERS IN PLANT SCIENCE 2017; 8:1199. [PMID: 28769939 PMCID: PMC5513917 DOI: 10.3389/fpls.2017.01199] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Accepted: 06/26/2017] [Indexed: 05/06/2023]
Abstract
Silicon (Si) is taken up from the soil as monosilicic acid by plant roots, transported to leaves and deposited as phytoliths, amorphous silica (SiO2) bodies, which are a key component of anti-herbivore defense in grasses. Silicon transporters have been identified in many plant species, but the mechanisms underpinning Si transport remain poorly understood. Specifically, the extent to which Si uptake is a passive process, driven primarily by transpiration, or has both passive and active components remains disputed. Increases in foliar Si concentration following herbivory suggest plants may exercise some control over Si uptake and distribution. In order to investigate passive and active controls on Si accumulation, we examined both genetic and environmental influences on Si accumulation in the forage grass Festuca arundinacea. We studied three F. arundinacea varieties that differ in the levels of Si they accumulate. Varieties not only differed in Si concentration, but also in increases in Si accumulation in response to leaf damage. The varietal differences in Si concentration generally reflected differences in stomatal density and stomatal conductance, suggesting passive, transpiration-mediated mechanisms underpin these differences. Bagging plants after damage was employed to minimize differences in stomatal conductance between varieties and in response to damage. This treatment eliminated constitutive differences in leaf Si levels, but did not impair the damage-induced increases in Si uptake: damaged, bagged plants still had more leaf Si than undamaged, bagged plants in all three varieties. Preliminary differential gene expression analysis revealed that the active Si transporter Lsi2 was highly expressed in damaged unbagged plants compared with undamaged unbagged plants, suggesting damage-induced Si defenses are regulated at gene level. Our findings suggest that although differences in transpiration may be partially responsible for varietal differences in Si uptake, they cannot explain damage-induced increases in Si uptake and deposition, suggesting that wounding causes changes in Si uptake, distribution and deposition that likely involve active processes and changes in gene expression.
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Affiliation(s)
- Emma McLarnon
- Department of Biology, University of YorkYork, United Kingdom
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18
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Meunier JD, Barboni D, Anwar-Ul-Haq M, Levard C, Chaurand P, Vidal V, Grauby O, Huc R, Laffont-Schwob I, Rabier J, Keller C. Effect of phytoliths for mitigating water stress in durum wheat. THE NEW PHYTOLOGIST 2017; 215:229-239. [PMID: 28394079 DOI: 10.1111/nph.14554] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2016] [Accepted: 02/28/2017] [Indexed: 05/22/2023]
Abstract
The role of silicon (Si) in alleviating biotic and abiotic stresses in crops is well evidenced by empirical studies; however, the mechanisms by which it works are still poorly known. The aim of this study is to determine whether or not phytolith composition and distribution in wheat are affected by drought and, if so, why. Durum wheat was grown using hydroponics in the presence of polyethylene glycol (PEG)-6000 to perform a water-stress simulation. We developed an original method for in situ analysis of phytoliths in leaves via X-ray imaging. PEG was efficient in inhibiting water uptake by roots and creating stress, and prevented a small fraction of Si from being accumulated in the shoots. The application of Si with PEG maintained shoot and root fresh weights (FW) and relative water content at higher values than for plants without Si, especially at PEG 12%. Our data show that, under water stress in the presence of Si, accumulation of phytoliths over the veins provides better support to the leaf, thus allowing for a better development of the whole plant than in the absence of Si. The development of silicified trichomes in durum wheat depends primarily on the availability of Si in soil and is not an adaptation to water stress.
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Affiliation(s)
- Jean Dominique Meunier
- CNRS, IRD, Coll France, CEREGE, Aix Marseille Université, 13545, Aix-en-Provence Cedex 04, France
| | - Doris Barboni
- CNRS, IRD, Coll France, CEREGE, Aix Marseille Université, 13545, Aix-en-Provence Cedex 04, France
| | - Muhammad Anwar-Ul-Haq
- Institute of Soil & Environmental Sciences, University of Agriculture, 38040, Faisalabad, Pakistan
| | - Clément Levard
- CNRS, IRD, Coll France, CEREGE, Aix Marseille Université, 13545, Aix-en-Provence Cedex 04, France
| | - Perrine Chaurand
- CNRS, IRD, Coll France, CEREGE, Aix Marseille Université, 13545, Aix-en-Provence Cedex 04, France
| | - Vladimir Vidal
- CNRS, IRD, Coll France, CEREGE, Aix Marseille Université, 13545, Aix-en-Provence Cedex 04, France
| | - Olivier Grauby
- CINaM, CNRS, Aix Marseille Université, Campus de Luminy Case 913, 13288, Marseille Cedex 9, France
| | - Roland Huc
- Unité Ecologie des Forêts Méditerranéennes (URFM), INRA, Domaine Saint Paul, Site Agroparc, 84914, Avignon Cedex 9, France
| | - Isabelle Laffont-Schwob
- CNRS, IRD, IMBE, Avignon University, Aix Marseille Université, Case 4, 3 Place Victor Hugo, 13331, Marseille Cedex 03, France
| | - Jacques Rabier
- CNRS, IRD, IMBE, Avignon University, Aix Marseille Université, Case 4, 3 Place Victor Hugo, 13331, Marseille Cedex 03, France
| | - Catherine Keller
- CNRS, IRD, Coll France, CEREGE, Aix Marseille Université, 13545, Aix-en-Provence Cedex 04, France
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19
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Frew A, Allsopp PG, Gherlenda AN, Johnson SN. Increased root herbivory under elevated atmospheric carbon dioxide concentrations is reversed by silicon-based plant defences. J Appl Ecol 2016. [DOI: 10.1111/1365-2664.12822] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Adam Frew
- Hawkesbury Institute for the Environment; Western Sydney University; Richmond NSW Australia
| | - Peter G. Allsopp
- Sugar Research Australia Limited; 50 Meiers Road Indooroopilly QLD Australia
| | - Andrew N. Gherlenda
- Hawkesbury Institute for the Environment; Western Sydney University; Richmond NSW Australia
| | - Scott N. Johnson
- Hawkesbury Institute for the Environment; Western Sydney University; Richmond NSW Australia
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20
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Cooke J, DeGabriel JL, Hartley SE. The functional ecology of plant silicon: geoscience to genes. Funct Ecol 2016. [DOI: 10.1111/1365-2435.12711] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- Julia Cooke
- Department of Earth, Environment and Ecosystems The Open University Walton Hall Milton Keynes MK7 6AA UK
| | - Jane L. DeGabriel
- Hawkesbury Institute for the Environment Western Sydney University Locked Bag 1797 Penrith New South Wales 2751 Australia
| | - Susan E. Hartley
- Department of Biology York Environmental Sustainability Institute University of York Heslington York YO10 5DD UK
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21
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Affiliation(s)
- Susan E. Hartley
- Department of Biology York Environmental Sustainability Institute University of York Heslington York YO10 5DD UK
| | - Jane L. DeGabriel
- Hawkesbury Institute for the Environment Western Sydney University Locked Bag 1797 Penrith New South Wales2751 Australia
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22
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Bråthen KA, Jahiri X, Jusdado JGH, Soininen EM, Jensen JB. Fungal endophyte diversity in tundra grasses increases by grazing. FUNGAL ECOL 2015. [DOI: 10.1016/j.funeco.2015.05.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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23
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Reynolds SC, Wilkinson DM, Marston CG, O'Regan HJ. The ‘mosaic habitat’ concept in human evolution: past and present. ACTA ACUST UNITED AC 2015. [DOI: 10.1080/0035919x.2015.1007490] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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24
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Hartley SE. Round and round in cycles? Silicon‐based plant defences and vole population dynamics. Funct Ecol 2015. [DOI: 10.1111/1365-2435.12365] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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25
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Hartley SE, Fitt RN, McLarnon EL, Wade RN. Defending the leaf surface: intra- and inter-specific differences in silicon deposition in grasses in response to damage and silicon supply. FRONTIERS IN PLANT SCIENCE 2015; 6:35. [PMID: 25717331 PMCID: PMC4324063 DOI: 10.3389/fpls.2015.00035] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Accepted: 01/14/2015] [Indexed: 05/06/2023]
Abstract
Understanding interactions between grasses and their herbivores is central to the conservation of species-rich grasslands and the protection of our most important crops against pests. Grasses employ a range of defenses against their natural enemies; silicon-based defenses have been shown to be one of the most effective. Silicon (Si) is laid down on the leaf surface as spines and other sharp bodies, known as phytoliths, making grasses abrasive and their foliage indigestible to herbivores. Previous studies on Si defenses found that closely related species may have similar levels of Si in the leaves but differ markedly in abrasiveness. Here we show how the number, shape and distribution of Si-rich phytoliths and spines differ within and between different grass species and demonstrate that species also differ in their ability to change the deposition and distribution of these defenses in response to damage or increases in Si supply. Specifically, we tested the response of two genotypes of Festuca arundinacea known to differ in their surface texture and three different grass species (F. ovina, F. rubra, and Deschampsia cespitosa) differing in their abrasiveness to combined manipulation of leaf damage and Si supply. F. arundinacea plants with a harsh leaf surface had higher Si content and more spines on their leaf surface than soft varieties. F. ovina and D. cespitosa plants increased their leaf Si concentration and produced an increase in the number of leaf spines and phytoliths on the leaf surface in response to Si addition. F rubra also increased leaf Si content in response to treatments, particularly in damaged leaves, but did not deposit this in the form of spines or increased densities of phytoliths. We discuss how the form in which grasses deposit Si may affect their anti-herbivore characteristics and consider the ecological and agricultural implications of the differences in allocation to Si-based defenses between grass species.
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Affiliation(s)
- Sue E. Hartley
- *Correspondence: Sue E. Hartley, Department of Biology, University of York, Wentworth Way, Heslington, York YO10 5DD, UK e-mail:
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26
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Schaller J, Hines J, Brackhage C, Bäucker E, Gessner MO. Silica decouples fungal growth and litter decomposition without changing responses to climate warming and N enrichment. Ecology 2014. [DOI: 10.1890/13-2104.1] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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27
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Huitu O, Forbes KM, Helander M, Julkunen-Tiitto R, Lambin X, Saikkonen K, Stuart P, Sulkama S, Hartley S. Silicon, endophytes and secondary metabolites as grass defenses against mammalian herbivores. FRONTIERS IN PLANT SCIENCE 2014; 5:478. [PMID: 25278951 PMCID: PMC4166226 DOI: 10.3389/fpls.2014.00478] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Accepted: 08/30/2014] [Indexed: 05/29/2023]
Abstract
Grasses have been considered to primarily employ tolerance in lieu of defense in mitigating damage caused by herbivory. Yet a number of mechanisms have been identified in grasses, which may deter feeding by grazers. These include enhanced silicon uptake, hosting of toxin-producing endophytic fungi and induction of secondary metabolites. While these mechanisms have been individually studied, their synergistic responses to grazing, as well as their effects on grazers, are poorly known. A field experiment was carried out in 5 × 5 m outdoor enclosures to quantify phytochemical changes of either endophyte-infected (E+) or endophyte-free (E-) meadow fescue (Schedonorus pratensis) in response to medium intensity (corresponding with densities of ca. 1200 voles/ha for 5 weeks during 3 months) or heavy intensity (ca. 1200 voles/ha for 8 weeks during 3 months) grazing by a mammalian herbivore, the field vole (Microtus agrestis). A laboratory experiment was then conducted to evaluate the effects of endophyte infection status and grazing history of the grass diet on vole performance. As predicted, grazing increased foliar silicon content, by up to 13%. Grazing also increased foliar levels of phosphorous and several phenolic compounds, most notably those of the flavonols isorhamnetin-diglycoside and rhamnetin derivative. Silicon concentrations were consistently circa 16% higher in E+ grasses than in E-grasses, at all levels of grazing. Similarly, concentrations of chlorogenic acid derivative were found to be consistently higher in E+ than in E- grasses. Female voles maintained on heavily grazed grasses suffered higher mortality rates in the laboratory than female voles fed ungrazed grass, regardless of endophyte infection status. Our results conclusively demonstrate that, in addition to tolerance, grasses employ multi-tiered, effective defenses against mammalian grazers.
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Affiliation(s)
- Otso Huitu
- Suonenjoki Research Unit, Finnish Forest Research InstituteSuonenjoki, Finland
| | - Kristian M. Forbes
- Suonenjoki Research Unit, Finnish Forest Research InstituteSuonenjoki, Finland
| | | | | | - Xavier Lambin
- School of Biological Sciences, University of AberdeenAberdeen, UK
| | - Kari Saikkonen
- Plant Protection, Agrifood Research FinlandJokioinen, Finland
| | - Peter Stuart
- Suonenjoki Research Unit, Finnish Forest Research InstituteSuonenjoki, Finland
| | - Sini Sulkama
- Suonenjoki Research Unit, Finnish Forest Research InstituteSuonenjoki, Finland
| | - Sue Hartley
- Department of Biology, University of YorkYork, UK
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28
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Katz O. Beyond grasses: the potential benefits of studying silicon accumulation in non-grass species. FRONTIERS IN PLANT SCIENCE 2014; 5:376. [PMID: 25132839 PMCID: PMC4116777 DOI: 10.3389/fpls.2014.00376] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Accepted: 07/14/2014] [Indexed: 05/06/2023]
Affiliation(s)
- Ofir Katz
- Department of Geography and Environmental Development, Ben-Gurion University of the NegevBe'er-Sheva, Israel
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29
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Quigley KM, Anderson TM. Leaf silica concentration in Serengeti grasses increases with watering but not clipping: insights from a common garden study and literature review. FRONTIERS IN PLANT SCIENCE 2014; 5:568. [PMID: 25374577 PMCID: PMC4204439 DOI: 10.3389/fpls.2014.00568] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Accepted: 10/02/2014] [Indexed: 05/23/2023]
Abstract
Grasses (Poaceae) lack the complex biochemical pathways and structural defenses employed by other plant families; instead they deposit microscopic silica (SiO2) granules in their leaf blades (i.e., phytoliths) as a putative defense strategy. Silica accumulation in grasses has generally been considered an inducible defense; other research suggests silica accumulation occurs by passive diffusion and should therefore be closely coupled with whole plant transpiration. We tested the hypothesis that grasses increase leaf silica concentration in response to artificial defoliation in a common garden study in the Serengeti ecosystem of East Africa. Additionally, a watering treatment tested the alternative hypothesis that leaf silica was largely driven by plant water status. Leaf silica content of two dominant C4 Serengeti grass species, Themeda triandra and Digitaria macroblephara, was quantified after a 10-month clipping × water experiment in which defoliation occurred approximately every 2 months and supplementary water was added every 2 weeks. Themeda had greater silica content than Digitaria, and Themeda also varied in foliar silica content according to collection site. Clipping had no significant effect on leaf silica in either species and watering significantly increased silica content of the dominant tall grass species, Themeda, but not the lawn species, Digitaria. Our data, and those collected as part of a supplementary literature review, suggest that silicon induction responses are contingent upon a combination of plant identity (i.e., species, genotype, life history limitations) and environmental factors (i.e., precipitation, soil nutrients, grazing intensity). Specifically, we propose that an interaction between plant functional type and water balance plays an especially important role in determining silica uptake and accumulation.
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Affiliation(s)
- Kathleen M. Quigley
- *Correspondence: Kathleen M. Quigley, Department of Biology, Wake Forest University, 1834 Wake Forest Road, Winston-Salem, NC 27109, USA e-mail:
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30
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Soininen EM, Ravolainen VT, Bråthen KA, Yoccoz NG, Gielly L, Ims RA. Arctic Small Rodents Have Diverse Diets and Flexible Food Selection. PLoS One 2013; 8:e68128. [PMID: 23826371 PMCID: PMC3694920 DOI: 10.1371/journal.pone.0068128] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Accepted: 05/28/2013] [Indexed: 11/18/2022] Open
Abstract
The ecology of small rodent food selection is poorly understood, as mammalian herbivore food selection theory has mainly been developed by studying ungulates. Especially, the effect of food availability on food selection in natural habitats where a range of food items are available is unknown. We studied diets and selectivity of grey-sided voles (Myodes rufocanus) and tundra voles (Microtus oeconomus), key herbivores in European tundra ecosystems, using DNA metabarcoding, a novel method enabling taxonomically detailed diet studies. In order to cover the range of food availabilities present in the wild, we employed a large-scale study design for sampling data on food availability and vole diets. Both vole species had ingested a range of plant species and selected particularly forbs and grasses. Grey-sided voles also selected ericoid shrubs and tundra voles willows. Availability of a food item rarely affected its utilization directly, although seasonal changes of diets and selection suggest that these are positively correlated with availability. Moreover, diets and selectivity were affected by availability of alternative food items. These results show that the focal sub-arctic voles have diverse diets and flexible food preferences and rarely compensate low availability of a food item with increased searching effort. Diet diversity itself is likely to be an important trait and has previously been underrated owing to methodological constraints. We suggest that the roles of alternative food item availability and search time limitations for small rodent feeding ecology should be investigated. Nomenclature Annotated Checklist of the Panarctic Flora (PAF), Vascular plants. Available at: http://nhm2.uio.no/paf/, accessed 15.6.2012.
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Affiliation(s)
- Eeva M. Soininen
- Department of Arctic and Marine Biology, University of Tromsø, Tromsø, Norway
- * E-mail:
| | - Virve T. Ravolainen
- Department of Arctic and Marine Biology, University of Tromsø, Tromsø, Norway
| | - Kari Anne Bråthen
- Department of Arctic and Marine Biology, University of Tromsø, Tromsø, Norway
| | - Nigel G. Yoccoz
- Department of Arctic and Marine Biology, University of Tromsø, Tromsø, Norway
| | - Ludovic Gielly
- Laboratoire d’ECologie Alpine, Université Joseph Fourier, Grenoble, France
| | - Rolf A. Ims
- Department of Arctic and Marine Biology, University of Tromsø, Tromsø, Norway
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