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Asgher M, Rehaman A, Nazar Ul Islam S, Khan NA. Multifaceted roles of silicon nano particles in heavy metals-stressed plants. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 341:122886. [PMID: 37952923 DOI: 10.1016/j.envpol.2023.122886] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 10/16/2023] [Accepted: 11/05/2023] [Indexed: 11/14/2023]
Abstract
Heavy metal (HM) contamination has emerged as one of the most damaging abiotic stress factors due to their prominent release into the environment through industrialization and urbanization worldwide. The increase in HMs concentration in soil and the environment has invited attention of researchers/environmentalists to minimize its' impact by practicing different techniques such as application of phytohormones, gaseous molecules, metalloids, and essential nutrients etc. Silicon (Si) although not considered as the essential nutrient, has received more attention in the last few decades due to its involvement in the amelioration of wide range of abiotic stress factors. Silicon is the second most abundant element after oxygen on earth, but is relatively lesser available for plants as it is taken up in the form of mono-silicic acid, Si(OH)4. The scattered information on the influence of Si on plant development and abiotic stress adaptation has been published. Moreover, the use of nanoparticles for maintenance of plant functions under limited environmental conditions has gained momentum. The current review, therefore, summarizes the updated information on Si nanoparticles (SiNPs) synthesis, characterization, uptake and transport mechanism, and their effect on plant growth and development, physiological and biochemical processes and molecular mechanisms. The regulatory connect between SiNPs and phytohormones signaling in counteracting the negative impacts of HMs stress has also been discussed.
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Affiliation(s)
- Mohd Asgher
- Plant Physiology and Biochemistry Laboratory, Department of Botany, Baba Ghulam Shah Badshah University, Rajouri, 185234, India
| | - Abdul Rehaman
- Plant Physiology and Biochemistry Laboratory, Department of Botany, Baba Ghulam Shah Badshah University, Rajouri, 185234, India
| | - Syed Nazar Ul Islam
- Plant Physiology and Biochemistry Laboratory, Department of Botany, Baba Ghulam Shah Badshah University, Rajouri, 185234, India
| | - Nafees A Khan
- Plant Physiology and Biochemistry Laboratory, Department of Botany, Aligarh Muslim University, Aligarh, 202002, India.
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Klotz M, Schaller J, Engelbrecht BMJ. Silicon-based anti-herbivore defense in tropical tree seedlings. FRONTIERS IN PLANT SCIENCE 2023; 14:1250868. [PMID: 37900768 PMCID: PMC10602810 DOI: 10.3389/fpls.2023.1250868] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 10/02/2023] [Indexed: 10/31/2023]
Abstract
Silicon-based defenses deter insect herbivores in many cultivated and wild grass species. Furthermore, in some of these species, silicon (Si) uptake and defense can be induced by herbivory. Tropical trees also take up Si and leaf Si concentrations vary greatly across and within species. As herbivory is a major driver of seedling mortality and niche differentiation of tropical tree species, understanding anti-herbivore defenses is pivotal. Yet, whether silicon is a constitutive and inducible herbivory defense in tropical forest tree species remains unknown. We grew seedlings of eight tropical tree species in a full factorial experiment, including two levels of plant-available soil Si concentrations (-Si/+Si) and a simulated herbivory treatment (-H/+H). The simulated herbivory treatment was a combination of clipping and application of methyl jasmonate. We then carried out multiple-choice feeding trials, separately for each tree species, in which leaves of each treatment combination were offered to a generalist caterpillar (Spodoptera frugiperda). Leaf damage was assessed. Three species showed a significant decrease in leaf damage under high compared to low Si conditions (by up to 72%), consistent with our expectation of Si-based defenses acting in tropical tree species. In one species, leaf damage was increased by increasing soil Si and in four species, no effect of soil Si on leaf damage was observed. Opposite to our expectation of Si uptake and defense being inducible by herbivory damage, simulated herbivory increased leaf damage in two species. Furthermore, simulated herbivory reduced Si concentrations in one species. Our results showed that tropical tree seedlings can be better defended when growing in Si-rich compared to Si-poor soils, and that the effects of Si on plant defense vary strongly across species. Furthermore, Si-based defenses may not be inducible in tropical tree species. Overall, constitutive Si-based defense should be considered part of the vast array of anti-herbivore defenses of tropical tree species. Our finding that Si-based defenses are highly species-specific combined with the fact that herbivory is a major driver of mortality in tropical tree seedling, suggests that variation in soil Si concentrations may have pervasive consequences for regeneration and performance across tropical tree species.
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Affiliation(s)
- Marius Klotz
- Leibniz Centre for Agricultural Landscape Research (ZALF), Müncheberg, Germany
- Deptartment of Plant Ecology, Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth, Bayreuth, Germany
| | - Jörg Schaller
- Leibniz Centre for Agricultural Landscape Research (ZALF), Müncheberg, Germany
| | - Bettina M. J. Engelbrecht
- Deptartment of Plant Ecology, Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth, Bayreuth, Germany
- Smithsonian Tropical Research Institute (STRI), Balboa, Panama
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3
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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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de Tombeur F, Raven JA, Toussaint A, Lambers H, Cooke J, Hartley SE, Johnson SN, Coq S, Katz O, Schaller J, Violle C. Why do plants silicify? Trends Ecol Evol 2023; 38:275-288. [PMID: 36428125 DOI: 10.1016/j.tree.2022.11.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 10/30/2022] [Accepted: 11/02/2022] [Indexed: 11/24/2022]
Abstract
Despite seminal papers that stress the significance of silicon (Si) in plant biology and ecology, most studies focus on manipulations of Si supply and mitigation of stresses. The ecological significance of Si varies with different levels of biological organization, and remains hard to capture. We show that the costs of Si accumulation are greater than is currently acknowledged, and discuss potential links between Si and fitness components (growth, survival, reproduction), environment, and ecosystem functioning. We suggest that Si is more important in trait-based ecology than is currently recognized. Si potentially plays a significant role in many aspects of plant ecology, but knowledge gaps prevent us from understanding its possible contribution to the success of some clades and the expansion of specific biomes.
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Affiliation(s)
- Félix de Tombeur
- CEFE, Univ Montpellier, CNRS, EPHE, IRD, Montpellier, France; School of Biological Sciences and Institute of Agriculture, The University of Western Australia, Perth, Australia.
| | - John A Raven
- Division of Plant Science, University of Dundee at the James Hutton Institute, Invergowrie, UK; School of Biological Sciences, The University of Western Australia, Perth, Australia; Climate Change Cluster, Faculty of Science, University of Technology Sydney, Ultimo, Australia
| | - Aurèle Toussaint
- Department of Botany, Institute of Ecology and Earth Sciences, University of Tartu, Tartu, Estonia
| | - Hans Lambers
- School of Biological Sciences and Institute of Agriculture, The University of Western Australia, Perth, Australia
| | - Julia Cooke
- School of Environment, Earth and Ecosystem Sciences, The Open University, Milton Keynes, UK
| | - Sue E Hartley
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK
| | - Scott N Johnson
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, Australia
| | - Sylvain Coq
- CEFE, Univ Montpellier, CNRS, EPHE, IRD, Montpellier, France
| | - Ofir Katz
- Dead Sea and Arava Science Center, Mount Masada, Tamar Regional Council, Israel; Eilat Campus, Ben-Gurion University of the Negev, Eilat, Israel
| | - Jörg Schaller
- Leibniz Centre for Agricultural Landscape Research (ZALF), Müncheberg, Germany
| | - Cyrille Violle
- CEFE, Univ Montpellier, CNRS, EPHE, IRD, Montpellier, France
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Johnson SN, Vandegeer RK, Borevitz JO, Hartley SE, Tissue DT, Hall CR. Climatic Drivers of Silicon Accumulation in a Model Grass Operate in Low- but Not High-Silicon Soils. PLANTS (BASEL, SWITZERLAND) 2023; 12:995. [PMID: 36903856 PMCID: PMC10005694 DOI: 10.3390/plants12050995] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 02/14/2023] [Accepted: 02/15/2023] [Indexed: 06/18/2023]
Abstract
Grasses are hyper-accumulators of silicon (Si), which is known to alleviate diverse environmental stresses, prompting speculation that Si accumulation evolved in response to unfavourable climatic conditions, including seasonally arid environments. We conducted a common garden experiment using 57 accessions of the model grass Brachypodium distachyon, sourced from different Mediterranean locations, to test relationships between Si accumulation and 19 bioclimatic variables. Plants were grown in soil with either low or high (Si supplemented) levels of bioavailable Si. Si accumulation was negatively correlated with temperature variables (annual mean diurnal temperature range, temperature seasonality, annual temperature range) and precipitation seasonality. Si accumulation was positively correlated with precipitation variables (annual precipitation, precipitation of the driest month and quarter, and precipitation of the warmest quarter). These relationships, however, were only observed in low-Si soils and not in Si-supplemented soils. Our hypothesis that accessions of B. distachyon from seasonally arid conditions have higher Si accumulation was not supported. On the contrary, higher temperatures and lower precipitation regimes were associated with lower Si accumulation. These relationships were decoupled in high-Si soils. These exploratory results suggest that geographical origin and prevailing climatic conditions may play a role in predicting patterns of Si accumulation in grasses.
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Affiliation(s)
- Scott N. Johnson
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW 2751, Australia
| | - Rebecca K. Vandegeer
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW 2751, Australia
| | - Justin O. Borevitz
- Research School of Biology, Australian National University, Canberra, ACT 2601, Australia
| | - Susan E. Hartley
- School of Biosciences, University of Sheffield, Sheffield S10 2TN, UK
| | - David T. Tissue
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW 2751, Australia
| | - Casey R. Hall
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW 2751, Australia
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de Tombeur F, Lemoine T, Violle C, Fréville H, Thorne S, Hartley SE, Lambers H, Fort F. Nitrogen availability and plant-plant interactions drive leaf silicon concentration in wheat genotypes. Funct Ecol 2022; 36:2833-2844. [PMID: 36606113 PMCID: PMC9804457 DOI: 10.1111/1365-2435.14170] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Accepted: 08/06/2022] [Indexed: 01/09/2023]
Abstract
Estimating plasticity of leaf silicon (Si) in response to abiotic and biotic factors underpins our comprehension of plant defences and stress resistance in natural and agroecosystems. However, how nitrogen (N) addition and intraspecific plant-plant interactions affect Si concentration remains unclear.We grew 19 durum wheat genotypes (Triticum turgidum ssp. durum) in pots, either alone or in intra- or intergenotypic cultures of two individuals, and with or without N. Above-ground biomass, plant height and leaf [Si] were quantified at the beginning of the flowering stage.Nitrogen addition decreased leaf [Si] for most genotypes, proportionally to the biomass increase. Si plasticity to plant-plant interactions varied significantly among genotypes, with both increases and decreases in leaf [Si] when mixed with a neighbour, regardless of the mixture type (intra-/intergenotype). Besides, increased leaf [Si] in response to plant-plant interactions was associated with increased plant height.Our results suggest the occurrence of both facilitation and competition for Si uptake from the rhizosphere in wheat mixtures. Future research should identify which leaf and root traits characterise facilitating neighbours for Si acquisition. We also show that Si could be involved in height gain in response to intraspecific competition, possibly for increasing light capture. This important finding opens up new research directions on Si and plant-plant interactions in both natural ecosystems and agroecosystems. More generally, our results stress the need to explore leaf Si plasticity in responses to both abiotic and biotic factors to understand plant stress resistance. Read the free Plain Language Summary for this article on the Journal blog.
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Affiliation(s)
- Felix de Tombeur
- CEFE, Univ Montpellier, CNRS, EPHE, IRDMontpellierFrance,School of Biological Sciences and Institute of AgricultureThe University of Western AustraliaPerthWAAustralia
| | - Taïna Lemoine
- CEFE, Univ Montpellier, CNRS, EPHE, IRDMontpellierFrance,AGAP, Univ Montpellier, CIRAD, INRAE, Institut AgroMontpellierFrance
| | - Cyrille Violle
- CEFE, Univ Montpellier, CNRS, EPHE, IRDMontpellierFrance
| | - Hélène Fréville
- AGAP, Univ Montpellier, CIRAD, INRAE, Institut AgroMontpellierFrance
| | - Sarah J. Thorne
- Department of BiologyUniversity of YorkYorkUK,School of BiosciencesUniversity of SheffieldSheffieldUK
| | | | - Hans Lambers
- School of Biological Sciences and Institute of AgricultureThe University of Western AustraliaPerthWAAustralia
| | - Florian Fort
- CEFE, Univ. Montpellier, L'Institut agro, CNRS, EPHE, IRDMontpellierFrance
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Okoroafor PU, Ogunkunle CO, Heilmeier H, Wiche O. Phytoaccumulation potential of nine plant species for selected nutrients, rare earth elements (REEs), germanium (Ge), and potentially toxic elements (PTEs) in soil. INTERNATIONAL JOURNAL OF PHYTOREMEDIATION 2022; 24:1310-1320. [PMID: 35014898 DOI: 10.1080/15226514.2021.2025207] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Given the possible benefits of phytoextraction, this study evaluated the potential of nine plant species for phytoaccumulation/co-accumulation of selected nutrients, rare earth elements, germanium, and potentially toxic elements. Plants were grown on 2 kg potted soils for 12 weeks in a greenhouse, followed by a measurement of dry shoot biomass. Subsequently, elemental concentrations were determined using inductively coupled mass spectrometry, followed by the determination of amounts of each element accumulated by the plant species. Results show varying accumulation behavior among plants for the different elements. Fagopyrum esculentum and Cannabis sativa were better accumulators of most elements investigated except for chromium, germanium, and silicon that were better accumulated by Zea mays, the only grass species. F. esculentum accumulated 9, 24, and 10% of Copper, Chromium, and Rare Earth Elements in the mobile/exchangeable element fraction of the soils while Z. mays and C. sativa accumulated amounts of Cr and Ge ∼58 and 17% (for Z. mays) and 20 and 9% (for C. sativa) of the mobile/exchangeable element fraction of the soils. Results revealed co-accumulation potential for some elements e.g., (1) Si, Ge, and Cr, (2) Cu and Pb, (3) P, Ca, Co, and REEs based on chemical similarities/sources of origin.
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Affiliation(s)
- Precious Uchenna Okoroafor
- Institute of Biosciences/Interdisciplinary Environmental Research Centre, Technische Universität Bergakademie Freiberg, Freiberg, Germany
| | | | - Hermann Heilmeier
- Institute of Biosciences/Interdisciplinary Environmental Research Centre, Technische Universität Bergakademie Freiberg, Freiberg, Germany
| | - Oliver Wiche
- Institute of Biosciences/Interdisciplinary Environmental Research Centre, Technische Universität Bergakademie Freiberg, Freiberg, Germany
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Galindo FS, Pagliari PH, Rodrigues WL, Fernandes GC, Boleta EHM, Santini JMK, Jalal A, Buzetti S, Lavres J, Teixeira Filho MCM. Silicon Amendment Enhances Agronomic Efficiency of Nitrogen Fertilization in Maize and Wheat Crops under Tropical Conditions. PLANTS 2021; 10:plants10071329. [PMID: 34209953 PMCID: PMC8309197 DOI: 10.3390/plants10071329] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 06/22/2021] [Accepted: 06/26/2021] [Indexed: 02/05/2023]
Abstract
Sustainable management strategies are needed to improve agronomic efficiency and cereal yield production under harsh abiotic climatic conditions such as in tropical Savannah. Under these environments, field-grown crops are usually exposed to drought and high temperature conditions. Silicon (Si) application could be a useful and sustainable strategy to enhance agronomic N use efficiency, leading to better cereal development. This study was developed to explore the effect of Si application as a soil amendment source (Ca and Mg silicate) associated with N levels applied in a side-dressing (control, low, medium and high N levels) on maize and wheat development, N uptake, agronomic efficiency and grain yield. The field experiments were carried out during four cropping seasons, using two soil amendment sources (Ca and Mg silicate and dolomitic limestone) and four N levels (0, 50, 100 and 200 kg N ha−1). The following evaluations were performed in maize and wheat crops: the shoots and roots biomass, total N, N-NO3−, N-NH4+ and Si accumulation in the shoots, roots and grain tissue, leaf chlorophyll index, grain yield and agronomic efficiency. The silicon amendment application enhanced leaf chlorophyll index, agronomic efficiency and N-uptake in maize and wheat plants, benefiting shoots and roots development and leading to a higher grain yield (an increase of 5.2 and 7.6%, respectively). It would be possible to reduce N fertilization in maize from 185–180 to 100 kg N ha−1 while maintaining similar grain yield with Si application. Additionally, Si application would reduce N fertilization in wheat from 195–200 to 100 kg N ha−1. Silicon application could be a key technology for improving plant-soil N-management, especially in Si accumulator crops, leading to a more sustainable cereal production under tropical conditions.
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Affiliation(s)
- Fernando Shintate Galindo
- Center for Nuclear Energy in Agriculture (CENA), University of São Paulo (USP), Piracicaba 13416-000, Brazil
- Correspondence:
| | - Paulo Humberto Pagliari
- Department of Soil, Water, and Climate, Southwest Research and Outreach Center (SWROC), University of Minnesota (UMN), Lamberton, MN 56152, USA;
| | - Willian Lima Rodrigues
- Department of Plant Health, Rural Engineering, and Soils (DEFERS), São Paulo State University (UNESP), Ilha Solteira 15345-000, Brazil; (W.L.R.); (G.C.F.); (E.H.M.B.); (J.M.K.S.); (A.J.); (S.B.); (J.L.); (M.C.M.T.F.)
| | - Guilherme Carlos Fernandes
- Department of Plant Health, Rural Engineering, and Soils (DEFERS), São Paulo State University (UNESP), Ilha Solteira 15345-000, Brazil; (W.L.R.); (G.C.F.); (E.H.M.B.); (J.M.K.S.); (A.J.); (S.B.); (J.L.); (M.C.M.T.F.)
| | - Eduardo Henrique Marcandalli Boleta
- Department of Plant Health, Rural Engineering, and Soils (DEFERS), São Paulo State University (UNESP), Ilha Solteira 15345-000, Brazil; (W.L.R.); (G.C.F.); (E.H.M.B.); (J.M.K.S.); (A.J.); (S.B.); (J.L.); (M.C.M.T.F.)
| | - José Mateus Kondo Santini
- Department of Plant Health, Rural Engineering, and Soils (DEFERS), São Paulo State University (UNESP), Ilha Solteira 15345-000, Brazil; (W.L.R.); (G.C.F.); (E.H.M.B.); (J.M.K.S.); (A.J.); (S.B.); (J.L.); (M.C.M.T.F.)
| | - Arshad Jalal
- Department of Plant Health, Rural Engineering, and Soils (DEFERS), São Paulo State University (UNESP), Ilha Solteira 15345-000, Brazil; (W.L.R.); (G.C.F.); (E.H.M.B.); (J.M.K.S.); (A.J.); (S.B.); (J.L.); (M.C.M.T.F.)
| | - Salatiér Buzetti
- Department of Plant Health, Rural Engineering, and Soils (DEFERS), São Paulo State University (UNESP), Ilha Solteira 15345-000, Brazil; (W.L.R.); (G.C.F.); (E.H.M.B.); (J.M.K.S.); (A.J.); (S.B.); (J.L.); (M.C.M.T.F.)
| | - José Lavres
- Department of Plant Health, Rural Engineering, and Soils (DEFERS), São Paulo State University (UNESP), Ilha Solteira 15345-000, Brazil; (W.L.R.); (G.C.F.); (E.H.M.B.); (J.M.K.S.); (A.J.); (S.B.); (J.L.); (M.C.M.T.F.)
| | - Marcelo Carvalho Minhoto Teixeira Filho
- Department of Plant Health, Rural Engineering, and Soils (DEFERS), São Paulo State University (UNESP), Ilha Solteira 15345-000, Brazil; (W.L.R.); (G.C.F.); (E.H.M.B.); (J.M.K.S.); (A.J.); (S.B.); (J.L.); (M.C.M.T.F.)
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Galindo FS, Pagliari PH, Buzetti S, Rodrigues WL, Fernandes GC, Biagini ALC, Marega EMR, Tavanti RFR, Jalal A, Teixeira Filho MCM. Corn shoot and grain nutrient uptake affected by silicon application combined with Azospirillum brasilense inoculation and nitrogen rates. JOURNAL OF PLANT NUTRITION 2021. [DOI: 10.1080/01904167.2021.1943436] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Fernando Shintate Galindo
- Department of Plant Health, Rural Engineering, and Soils, São Paulo State University, Ilha Solteira, Brazil
| | - Paulo Humberto Pagliari
- Department of Soil, Water, and Climate, University of Minnesota, Southwest Research and Outreach Center, Lamberton, MN, USA
| | - Salatiér Buzetti
- Department of Plant Health, Rural Engineering, and Soils, São Paulo State University, Ilha Solteira, Brazil
| | - Willian Lima Rodrigues
- Department of Plant Health, Rural Engineering, and Soils, São Paulo State University, Ilha Solteira, Brazil
| | - Guilherme Carlos Fernandes
- Department of Plant Health, Rural Engineering, and Soils, São Paulo State University, Ilha Solteira, Brazil
| | | | - Evelyn Maria Rocha Marega
- Department of Plant Health, Rural Engineering, and Soils, São Paulo State University, Ilha Solteira, Brazil
| | | | - Arshad Jalal
- Department of Plant Health, Rural Engineering, and Soils, São Paulo State University, Ilha Solteira, Brazil
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Vandegeer RK, Cibils‐Stewart X, Wuhrer R, Hartley SE, Tissue DT, Johnson SN. Leaf silicification provides herbivore defence regardless of the extensive impacts of water stress. Funct Ecol 2021. [DOI: 10.1111/1365-2435.13794] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Rebecca K. Vandegeer
- Hawkesbury Institute for the Environment Western Sydney University Penrith NSW Australia
| | - Ximena Cibils‐Stewart
- Hawkesbury Institute for the Environment Western Sydney University Penrith NSW Australia
- Instituto Nacional de Investigación Agropecuaria (INIA) Colonia Uruguay
| | - Richard Wuhrer
- Advanced Materials Characterisation Facility Western Sydney University Penrith NSW Australia
| | - Susan E. Hartley
- Department of Animal and Plant Sciences University of Sheffield Sheffield UK
| | - David T. Tissue
- Hawkesbury Institute for the Environment Western Sydney University Penrith NSW Australia
| | - Scott N. Johnson
- Hawkesbury Institute for the Environment Western Sydney University Penrith NSW Australia
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11
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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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12
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Johnson SN, Hartley SE, Ryalls JMW, Frew A, Hall CR. Targeted plant defense: silicon conserves hormonal defense signaling impacting chewing but not fluid-feeding herbivores. Ecology 2021; 102:e03250. [PMID: 33219513 DOI: 10.1002/ecy.3250] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 09/03/2020] [Accepted: 09/18/2020] [Indexed: 01/01/2023]
Abstract
Plants deploy an arsenal of chemical and physical defenses against arthropod herbivores, but it may be most cost efficient to produce these only when attacked. Herbivory activates complex signaling pathways involving several phytohormones, including jasmonic acid (JA), which regulate production of defensive compounds. The Poaceae also have the capacity to take up large amounts of silicon (Si), which accumulates in plant tissues. Si accumulation has antiherbivore properties, but it is poorly understood how Si defenses relate to defense hormone signaling. Here we show that Si enrichment causes the model grass Brachypodium distachyon to show lower levels of JA induction when attacked by chewing herbivores. Triggering this hormone even at lower concentrations, however, prompts Si uptake and physical defenses (e.g., leaf hairs), which negatively impact chewing herbivores. Removal of leaf hairs restored performance. Crucially, activation of such Si-based defense is herbivore-specific and occurred only in response to chewing and not fluid-feeding (aphid) herbivores. This aligned with our meta-analysis of 88 studies that showed Si defenses were more effective against chewing herbivores than fluid feeders. Our results suggest integration between herbivore defenses in a model Si-accumulating plant, which potentially allows it to avoid unnecessary activation of other costly defenses.
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Affiliation(s)
- Scott N Johnson
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, New South Wales, 2751, Australia
| | - Susan E Hartley
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK
| | - James M W Ryalls
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, New South Wales, 2751, Australia.,Centre for Agri-Environmental Research, School of Agriculture, Policy and Development, University of Reading, Reading, UK
| | - Adam Frew
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, New South Wales, 2751, Australia.,Centre for Crop Health, University of Southern Queensland, Toowoomba, Queensland, 4350, Australia
| | - Casey R Hall
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, New South Wales, 2751, Australia
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13
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Zexer N, Elbaum R. Unique lignin modifications pattern the nucleation of silica in sorghum endodermis. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:6818-6829. [PMID: 32154874 PMCID: PMC7709913 DOI: 10.1093/jxb/eraa127] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Accepted: 03/06/2020] [Indexed: 05/04/2023]
Abstract
Silicon dioxide in the form of hydrated silica is a component of plant tissues that can constitute several percent by dry weight in certain taxa. Nonetheless, the mechanism of plant silica formation is mostly unknown. Silicon (Si) is taken up from the soil by roots in the form of monosilicic acid molecules. The silicic acid is carried in the xylem and subsequently polymerizes in target sites to silica. In roots of sorghum (Sorghum bicolor), silica aggregates form in an orderly pattern along the inner tangential cell walls of endodermis cells. Using Raman microspectroscopy, autofluorescence, and scanning electron microscopy, we investigated the structure and composition of developing aggregates in roots of sorghum seedlings. Putative silica aggregation loci were identified in roots grown under Si starvation. These micrometer-scale spots were constructed of tightly packed modified lignin, and nucleated trace concentrations of silicic acid. Substantial variation in cell wall autofluorescence between Si+ and Si- roots demonstrated the impact of Si on cell wall chemistry. We propose that in Si- roots, the modified lignin cross-linked into the cell wall and lost its ability to nucleate silica. In Si+ roots, silica polymerized on the modified lignin and altered its structure. Our work demonstrates a high degree of control over lignin and silica deposition in cell walls.
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Affiliation(s)
- Nerya Zexer
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Rivka Elbaum
- The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot, Israel
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14
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Kumar S, Adiram-Filiba N, Blum S, Sanchez-Lopez JA, Tzfadia O, Omid A, Volpin H, Heifetz Y, Goobes G, Elbaum R. Siliplant1 protein precipitates silica in sorghum silica cells. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:6830-6843. [PMID: 32485738 DOI: 10.1093/jxb/eraa258] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Accepted: 05/26/2020] [Indexed: 05/26/2023]
Abstract
Silicon is absorbed by plant roots as silicic acid. The acid moves with the transpiration stream to the shoot, and mineralizes as silica. In grasses, leaf epidermal cells called silica cells deposit silica in most of their volume using an unknown biological factor. Using bioinformatics tools, we identified a previously uncharacterized protein in Sorghum bicolor, which we named Siliplant1 (Slp1). Slp1 is a basic protein with seven repeat units rich in proline, lysine, and glutamic acid. We found Slp1 RNA in sorghum immature leaf and immature inflorescence. In leaves, transcription was highest just before the active silicification zone (ASZ). There, Slp1 was localized specifically to developing silica cells, packed inside vesicles and scattered throughout the cytoplasm or near the cell boundary. These vesicles fused with the membrane, releasing their content in the apoplastic space. A short peptide that is repeated five times in Slp1 precipitated silica in vitro at a biologically relevant silicic acid concentration. Transient overexpression of Slp1 in sorghum resulted in ectopic silica deposition in all leaf epidermal cell types. Our results show that Slp1 precipitates silica in sorghum silica cells.
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Affiliation(s)
- Santosh Kumar
- Robert H Smith Institute of Plant Sciences and Genetics in Agriculture, Robert H Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot, Israel
| | | | - Shula Blum
- Robert H Smith Institute of Plant Sciences and Genetics in Agriculture, Robert H Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot, Israel
| | - Javier Arturo Sanchez-Lopez
- Department of Entomology, Robert H Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot, Israel
| | - Oren Tzfadia
- Bioinformatics and Systems Biology, VIB/Ghent University, Gent, Belgium
| | - Ayelet Omid
- Danziger Innovations Limited, Mishmar Hashiva, Israel
| | - Hanne Volpin
- Danziger Innovations Limited, Mishmar Hashiva, Israel
| | - Yael Heifetz
- Department of Entomology, Robert H Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot, Israel
| | - Gil Goobes
- Department of Chemistry, Bar-Ilan University, Ramat Gan, Israel
| | - Rivka Elbaum
- Robert H Smith Institute of Plant Sciences and Genetics in Agriculture, Robert H Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot, Israel
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15
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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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16
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Deshmukh R, Sonah H, Belanger RR. New evidence defining the evolutionary path of aquaporins regulating silicon uptake in land plants. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:6775-6788. [PMID: 32710120 DOI: 10.1093/jxb/eraa342] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 07/20/2020] [Indexed: 05/26/2023]
Abstract
Understanding the evolution events defining silicon (Si) uptake in plant species is important for the efficient exploration of Si-derived benefits. In the present study, Si accumulation was studied in 456 diverse plant species grown in uniform field conditions, and in a subset of 151 species grown under greenhouse conditions, allowing efficient comparison among the species. In addition, a systematic analysis of nodulin 26-like intrinsic proteins III (NIP-III), which form Si channels, was performed in >1000 species to trace their evolutionary path and link with Si accumulation. Significant variations in Si accumulation were observed among the plant species studied. For their part, species lacking NIP-IIIs systematically showed low Si accumulation. Interestingly, seven NIP-IIIs were identified in three moss species, namely Physcomitrella patens, Andreaea rupestris, and Scouleria aquatica, indicating that the evolution of NIP-IIIs dates back as early as 515 million years ago. These results were further supported from previous reports of Si deposition in moss fossils estimated to be from around the Ordovician era. The taxonomical distribution provided in the present study will be helpful for several other disciplines, such as palaeoecology and geology, that define the biogeochemical cycling of Si. In addition to the prediction of Si uptake potential of plant species based on sequence information and taxonomical positioning, the evolutionary path of the Si uptake mechanism described here will be helpful to understand the Si environment over the different eras of land plant evolution.
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Affiliation(s)
- Rupesh Deshmukh
- Département de Phytologie, Faculté des Sciences de l'Agriculture et de l'Alimentation (FSAA), Université Laval, Québec, QC, Canada
- National Agri-Food Biotechnology Institute (NABI), Mohali, India
| | - Humira Sonah
- Département de Phytologie, Faculté des Sciences de l'Agriculture et de l'Alimentation (FSAA), Université Laval, Québec, QC, Canada
- National Agri-Food Biotechnology Institute (NABI), Mohali, India
| | - Richard R Belanger
- Département de Phytologie, Faculté des Sciences de l'Agriculture et de l'Alimentation (FSAA), Université Laval, Québec, QC, Canada
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17
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Ahanger MA, Bhat JA, Siddiqui MH, Rinklebe J, Ahmad P. Integration of silicon and secondary metabolites in plants: a significant association in stress tolerance. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:6758-6774. [PMID: 32585681 DOI: 10.1093/jxb/eraa291] [Citation(s) in RCA: 70] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 06/16/2020] [Indexed: 05/03/2023]
Abstract
As sessile organisms, plants are unable to avoid being subjected to environmental stresses that negatively affect their growth and productivity. Instead, they utilize various mechanisms at the morphological, physiological, and biochemical levels to alleviate the deleterious effects of such stresses. Amongst these, secondary metabolites produced by plants represent an important component of the defense system. Secondary metabolites, namely phenolics, terpenes, and nitrogen-containing compounds, have been extensively demonstrated to protect plants against multiple stresses, both biotic (herbivores and pathogenic microorganisms) and abiotic (e.g. drought, salinity, and heavy metals). The regulation of secondary metabolism by beneficial elements such as silicon (Si) is an important topic. Silicon-mediated alleviation of both biotic and abiotic stresses has been well documented in numerous plant species. Recently, many studies have demonstrated the involvement of Si in strengthening stress tolerance through the modulation of secondary metabolism. In this review, we discuss Si-mediated regulation of the synthesis, metabolism, and modification of secondary metabolites that lead to enhanced stress tolerance, with a focus on physiological, biochemical, and molecular aspects. Whilst mechanisms involved in Si-mediated regulation of pathogen resistance via secondary metabolism have been established in plants, they are largely unknown in the case of abiotic stresses, thus leaving an important gap in our current knowledge.
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Affiliation(s)
| | - Javaid Akhter Bhat
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, College of Agriculture, Nanjing Agricultural University, Nanjing, China
| | - Manzer H Siddiqui
- Botany and Microbiology Department, College of Science, King Saud University, Riyadh, Saudi Arabia
| | - Jörg Rinklebe
- University of Wuppertal, School of Architecture and Civil Engineering, Institute of Foundation Engineering, Water- and Waste-Management, Laboratory of Soil- and Groundwater-Management, Pauluskirchstraße 7, Wuppertal, Germany
- Department of Environment, Energy, and Geoinformatics, Sejong University, Seoul, Republic of Korea
| | - Parvaiz Ahmad
- Botany and Microbiology Department, College of Science, King Saud University, Riyadh, Saudi Arabia
- Department of Botany, S.P. College Srinagar, Jammu and Kashmir, India
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18
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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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19
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Thorne SJ, Hartley SE, Maathuis FJM. Is Silicon a Panacea for Alleviating Drought and Salt Stress in Crops? FRONTIERS IN PLANT SCIENCE 2020; 11:1221. [PMID: 32973824 PMCID: PMC7461962 DOI: 10.3389/fpls.2020.01221] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 07/27/2020] [Indexed: 05/04/2023]
Abstract
Salinity affects around 20% of all arable land while an even larger area suffers from recurrent drought. Together these stresses suppress global crop production by as much as 50% and their impacts are predicted to be exacerbated by climate change. Infrastructure and management practices can mitigate these detrimental impacts, but are costly. Crop breeding for improved tolerance has had some success but is progressing slowly and is not keeping pace with climate change. In contrast, Silicon (Si) is known to improve plant tolerance to a range of stresses and could provide a sustainable, rapid and cost-effective mitigation method. The exact mechanisms are still under debate but it appears Si can relieve salt stress via accumulation in the root apoplast where it reduces "bypass flow of ions to the shoot. Si-dependent drought relief has been linked to lowered root hydraulic conductance and reduction of water loss through transpiration. However, many alternative mechanisms may play a role such as altered gene expression and increased accumulation of compatible solutes. Oxidative damage that occurs under stress conditions can be reduced by Si through increased antioxidative enzymes while Si-improved photosynthesis has also been reported. Si fertilizer can be produced relatively cheaply and to assess its economic viability to improve crop stress tolerance we present a cost-benefit analysis. It suggests that Si fertilization may be beneficial in many agronomic settings but may be beyond the means of smallholder farmers in developing countries. Si application may also have disadvantages, such as increased soil pH, less efficient conversion of crops into biofuel and reduced digestibility of animal fodder. These issues may hamper uptake of Si fertilization as a routine agronomic practice. Here, we critically evaluate recent literature, quantifying the most significant physiological changes associated with Si in plants under drought and salinity stress. Analyses show that metrics associated with photosynthesis, water balance and oxidative stress all improve when Si is present during plant exposure to salinity and drought. We further conclude that most of these changes can be explained by apoplastic roles of Si while there is as yet little evidence to support biochemical roles of this element.
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Affiliation(s)
- Sarah J. Thorne
- Department of Biology, University of York, York, United Kingdom
| | - Susan E. Hartley
- Department of Biology, University of Sheffield, Sheffield, United Kingdom
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20
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Investigation of Azospirillum brasilense Inoculation and Silicon Application on Corn Yield Responses. JOURNAL OF SOIL SCIENCE AND PLANT NUTRITION 2020. [DOI: 10.1007/s42729-020-00306-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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21
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Galindo FS, Buzetti S, Rodrigues WL, Boleta EHM, Silva VM, Tavanti RFR, Fernandes GC, Biagini ALC, Rosa PAL, Teixeira Filho MCM. Inoculation of Azospirillum brasilense associated with silicon as a liming source to improve nitrogen fertilization in wheat crops. Sci Rep 2020; 10:6160. [PMID: 32273589 PMCID: PMC7145820 DOI: 10.1038/s41598-020-63095-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Accepted: 03/24/2020] [Indexed: 02/05/2023] Open
Abstract
This research was developed to investigate whether inoculation with Azospirillum brasilense in combination with silicon (Si) can enhance N use efficiency (NUE) in wheat and to evaluate and correlate nutritional and productive components and wheat grain yield. The study was carried out on a Rhodic Hapludox under a no-till system with a completely randomized block design with four replications in a 2 × 2 × 5 factorial scheme: two liming sources (with Ca and Mg silicate as the Si source and limestone); two inoculations (control - without inoculation and seed inoculation with A. brasilense) and five side-dress N rates (0, 50, 100, 150 and 200 kg ha-1). The results of this study showed positive improvements in wheat growth production parameters, NUE and grain yield as a function of inoculation associated with N rates. Inoculation can complement and optimize N fertilization, even with high N application rates. The potential benefits of Si use were less evident; however, the use of Si can favour N absorption, even when associated with A. brasilense. Therefore, studies conducted under tropical conditions with Ca and Mg silicate are necessary to better understand the role of Si applied alone or in combination with growth-promoting bacteria such as A. brasilense.
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Affiliation(s)
- Fernando Shintate Galindo
- São Paulo State University (UNESP), College of Engineering of Ilha Solteira, Department of Plant Health, Rural Engineering, and Soils, P.O. BOX 15385-000, Av. Brasil Sul, 830 - Centro, Ilha Solteira, state of São Paulo, Brazil
| | - Salatiér Buzetti
- São Paulo State University (UNESP), College of Engineering of Ilha Solteira, Department of Plant Health, Rural Engineering, and Soils, P.O. BOX 15385-000, Av. Brasil Sul, 830 - Centro, Ilha Solteira, state of São Paulo, Brazil
| | - Willian Lima Rodrigues
- São Paulo State University (UNESP), College of Engineering of Ilha Solteira, Department of Plant Health, Rural Engineering, and Soils, P.O. BOX 15385-000, Av. Brasil Sul, 830 - Centro, Ilha Solteira, state of São Paulo, Brazil
| | - Eduardo Henrique Marcandalli Boleta
- São Paulo State University (UNESP), College of Engineering of Ilha Solteira, Department of Plant Health, Rural Engineering, and Soils, P.O. BOX 15385-000, Av. Brasil Sul, 830 - Centro, Ilha Solteira, state of São Paulo, Brazil
| | - Vinicius Martins Silva
- São Paulo State University (UNESP), College of Engineering of Ilha Solteira, Department of Plant Health, Rural Engineering, and Soils, P.O. BOX 15385-000, Av. Brasil Sul, 830 - Centro, Ilha Solteira, state of São Paulo, Brazil
| | - Renan Francisco Rimoldi Tavanti
- São Paulo State University (UNESP), College of Engineering of Ilha Solteira, Department of Plant Health, Rural Engineering, and Soils, P.O. BOX 15385-000, Av. Brasil Sul, 830 - Centro, Ilha Solteira, state of São Paulo, Brazil
| | - Guilherme Carlos Fernandes
- São Paulo State University (UNESP), College of Engineering of Ilha Solteira, Department of Plant Health, Rural Engineering, and Soils, P.O. BOX 15385-000, Av. Brasil Sul, 830 - Centro, Ilha Solteira, state of São Paulo, Brazil
| | - Antônio Leonardo Campos Biagini
- São Paulo State University (UNESP), College of Engineering of Ilha Solteira, Department of Plant Health, Rural Engineering, and Soils, P.O. BOX 15385-000, Av. Brasil Sul, 830 - Centro, Ilha Solteira, state of São Paulo, Brazil
| | - Poliana Aparecida Leonel Rosa
- São Paulo State University (UNESP), College of Engineering of Ilha Solteira, Department of Plant Health, Rural Engineering, and Soils, P.O. BOX 15385-000, Av. Brasil Sul, 830 - Centro, Ilha Solteira, state of São Paulo, Brazil
| | - Marcelo Carvalho Minhoto Teixeira Filho
- São Paulo State University (UNESP), College of Engineering of Ilha Solteira, Department of Plant Health, Rural Engineering, and Soils, P.O. BOX 15385-000, Av. Brasil Sul, 830 - Centro, Ilha Solteira, state of São Paulo, Brazil.
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22
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Galindo FS, Pagliari PH, Buzetti S, Rodrigues WL, Santini JMK, Boleta EHM, Rosa PAL, Rodrigues Nogueira TA, Lazarini E, Filho MCMT. Can silicon applied to correct soil acidity in combination with Azospirillum brasilense inoculation improve nitrogen use efficiency in maize? PLoS One 2020; 15:e0230954. [PMID: 32267854 PMCID: PMC7141695 DOI: 10.1371/journal.pone.0230954] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Accepted: 03/12/2020] [Indexed: 02/05/2023] Open
Abstract
Alternative management practices are needed to minimize the need for chemical fertilizer use in non-leguminous cropping systems. The use of biological agents that can fix atmospheric N has shown potential to improve nutrient availability in grass crops. This research was developed to investigate if inoculation with Azospirillum brasilense in combination with silicon (Si) can enhance N use efficiency (NUE) in maize. The study was set up in a Rhodic Hapludox under a no-till system, in a completely randomized block design with four replicates. Treatments were tested in a full factorial design and included: i) five side dress N rates (0 to 200 kg ha-1); ii) two liming sources (Ca and Mg silicate and dolomitic limestone); and iii) with and without seed inoculation with A. brasilense. Inoculation with A. brasilense was found to increase grain yield by 15% when N was omitted and up to 10% when N was applied. Inoculation also increased N accumulation in plant tissue. Inoculation and limestone application were found to increase leaf chlorophyll index, number of grains per ear, harvest index, and NUE. Inoculation increased harvest index and NUE by 9.5 and 19.3%, respectively, compared with non-inoculated plots. Silicon application increased leaf chlorophyll index and N-leaf concentration. The combination of Si and inoculation provided greater Si-shoot accumulation. This study showed positive improvements in maize growth production parameters as a result of inoculation, but the potential benefits of Si use were less evident. Further research should be conducted under growing conditions that provide some level of biotic or abiotic stress to study the true potential of Si application.
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Affiliation(s)
- Fernando Shintate Galindo
- Department of Plant Health, Rural Engineering, and Soils, São Paulo State University, Ilha Solteira, São Paulo, Brazil
| | - Paulo Humberto Pagliari
- Department of Soil, Water, and Climate, University of Minnesota, Southwest Research and Outreach Center, Lamberton, Minnesota, United States of America
| | - Salatiér Buzetti
- Department of Plant Health, Rural Engineering, and Soils, São Paulo State University, Ilha Solteira, São Paulo, Brazil
| | - Willian Lima Rodrigues
- Department of Plant Health, Rural Engineering, and Soils, São Paulo State University, Ilha Solteira, São Paulo, Brazil
| | | | | | - Poliana Aparecida Leonel Rosa
- Department of Plant Health, Rural Engineering, and Soils, São Paulo State University, Ilha Solteira, São Paulo, Brazil
| | | | - Edson Lazarini
- Department of Plant Health, Rural Engineering, and Soils, São Paulo State University, Ilha Solteira, São Paulo, Brazil
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23
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Hall CR, Mikhael M, Hartley SE, Johnson SN. Elevated atmospheric CO
2
suppresses jasmonate and silicon‐based defences without affecting herbivores. Funct Ecol 2020. [DOI: 10.1111/1365-2435.13549] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Casey R. Hall
- Hawkesbury Institute for the Environment Western Sydney University Richmond NSW Australia
| | - Meena Mikhael
- School of Medicine Western Sydney University Campbelltown NSW Australia
| | - Susan E. Hartley
- Department of Animal and Plant Sciences University of Sheffield Sheffield UK
| | - Scott N. Johnson
- Hawkesbury Institute for the Environment Western Sydney University Richmond NSW Australia
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Assessing Forms of Application of Azospirillum brasilense Associated with Silicon Use on Wheat. AGRONOMY 2019. [DOI: 10.3390/agronomy9110678] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The use of biological techniques such as plant growth-promoting bacteria (PGPB) can represent a sustainable alternative for cereal growth in tropical areas. Research showing the potential for management practices which optimize PGPB inoculation is of utmost importance. This research was developed to investigate the potential use of Azospirillum brasilense in wheat cropping systems, as well as to assess the potential synergistic interactions between the beneficial use of silicon (Si), principally under abiotic and biotic conditions, and A. brasilense forms of application and how they impact crop development and wheat yield. The study was set up in a Rhodic Hapludox under a no-till system. The experimental design was a completely randomized block design with four replicates arranged in a factorial scheme with four inoculation forms (control, seed, groove, and leaf) and two soil acidity corrective sources (Ca and Mg silicate as Si source and dolomitic limestone). Seed inoculation was more effective in promoting wheat growth and development, with higher yield, showing an increase of 26.7% in wheat grain yield. Calcium and magnesium silicate application associated with foliar inoculation and without A. brasilense inoculation can increase wheat grain yield.
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Johnson SN, Ryalls JMW, Barton CVM, Tjoelker MG, Wright IJ, Moore BD. Climate warming and plant biomechanical defences: Silicon addition contributes to herbivore suppression in a pasture grass. Funct Ecol 2019. [DOI: 10.1111/1365-2435.13295] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Scott N. Johnson
- Hawkesbury Institute for the Environment Western Sydney University Sydney New South Wales Australia
| | - James M. W. Ryalls
- Hawkesbury Institute for the Environment Western Sydney University Sydney New South Wales Australia
| | - Craig V. M. Barton
- Hawkesbury Institute for the Environment Western Sydney University Sydney New South Wales Australia
| | - Mark G. Tjoelker
- Hawkesbury Institute for the Environment Western Sydney University Sydney New South Wales Australia
| | - Ian J. Wright
- Department of Biological Sciences Macquarie University Sydney New South Wales Australia
| | - Ben D. Moore
- Hawkesbury Institute for the Environment Western Sydney University Sydney New South Wales Australia
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Hall CR, Waterman JM, Vandegeer RK, Hartley SE, Johnson SN. The Role of Silicon in Antiherbivore Phytohormonal Signalling. FRONTIERS IN PLANT SCIENCE 2019; 10:1132. [PMID: 31620157 PMCID: PMC6759751 DOI: 10.3389/fpls.2019.01132] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Accepted: 08/15/2019] [Indexed: 05/22/2023]
Abstract
The role of plant silicon (Si) in the alleviation of abiotic and biotic stress is now widely recognised and researched. Amongst the biotic stresses, Si is known to increase resistance to herbivores through biomechanical and chemical mechanisms, although the latter are indirect and remain poorly characterised. Chemical defences are principally regulated by several antiherbivore phytohormones. The jasmonic acid (JA) signalling pathway is particularly important and has been linked to Si supplementation, albeit with some contradictory findings. In this Perspectives article, we summarise existing knowledge of how Si affects JA in the context of herbivory and present a conceptual model for the interactions between Si and JA signalling in wounded plants. Further, we use novel information from the model grass Brachypodium distachyon to underpin aspects of this model. We show that Si reduces JA concentrations in plants subjected to chemical induction (methyl jasmonate) and herbivory (Helicoverpa armigera) by 34% and 32%, respectively. Moreover, +Si plants had 13% more leaf macrohairs than -Si plants. From this study and previous work, our model proposes that Si acts as a physical stimulus in the plant, which causes a small, transient increase in JA. When +Si plants are subsequently attacked by herbivores, they potentially show a faster induction of JA due to this priming. +Si plants that have already invested in biomechanical defences (e.g. macrohairs), however, have less utility for JA-induced defences and show lower levels of JA induction overall.
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Affiliation(s)
- Casey R. Hall
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
| | - Jamie M. Waterman
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
| | - Rebecca K. Vandegeer
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
| | - Susan E. Hartley
- York Environment and Sustainability Institute, Department of Biology, University of York, York, United Kingdom
| | - Scott N. Johnson
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
- *Correspondence: Scott Johnson,
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Ryalls JMW, Moore BD, Johnson SN. Silicon uptake by a pasture grass experiencing simulated grazing is greatest under elevated precipitation. BMC Ecol 2018; 18:53. [PMID: 30514265 PMCID: PMC6280423 DOI: 10.1186/s12898-018-0208-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 11/22/2018] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND Grasses are hyper-accumulators of silicon (Si) and often up-regulate Si following herbivory. Positive correlations exist between Si and plant water content, yet the extent to which Si uptake responses can be mediated by changes in soil water availability has rarely been studied and never, to our knowledge, under field conditions. We used field-based rain-exclusion shelters to investigate how simulated grazing (shoot clipping) and altered rainfall patterns (drought and elevated precipitation, representing 50% and 150% of ambient precipitation levels, respectively) affected initial patterns of root- and shoot-Si uptake in a native Australian grass (Microlaena stipoides) in Si-supplemented and untreated soils. RESULTS Si supplementation increased soil water retention under ambient and elevated precipitation but not under drought, although this had little effect on Si uptake and growth (tiller numbers or root biomass) of M. stipoides. Changes in rainfall patterns and clipping had strong individual effects on plant growth and Si uptake and storage, whereby clipping increased Si uptake by M. stipoides under all rainfall treatments but to the greatest extent under elevated precipitation. Moreover, above-ground-below-ground Si distribution only changed following elevated precipitation by decreasing the ratio of root:shoot Si concentrations. CONCLUSIONS Results highlight the importance of soil water availability for Si uptake and suggest a role for both active and passive Si transport mechanisms. Such manipulative field studies may provide a more realistic insight into how grasses initially respond to herbivory in terms of Si-based defence under different environmental conditions.
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Affiliation(s)
- James M. W. Ryalls
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW Australia
- Centre for Agri-Environmental Research, School of Agriculture, Policy and Development, University of Reading, Reading, UK
| | - Ben D. Moore
- 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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Johnson SN, Hartley SE. Elevated carbon dioxide and warming impact silicon and phenolic-based defences differently in native and exotic grasses. GLOBAL CHANGE BIOLOGY 2018; 24:3886-3896. [PMID: 29105229 DOI: 10.1111/gcb.13971] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Accepted: 10/12/2017] [Indexed: 05/22/2023]
Abstract
Global climate change may increase invasions of exotic plant species by directly promoting the success of invasive/exotic species or by reducing the competitive abilities of native species. Changes in plant chemistry, leading to altered susceptibility to stress, could mediate these effects. Grasses are hyper-accumulators of silicon, which play a crucial function in the alleviation of diverse biotic and abiotic stresses. It is unknown how predicted increases in atmospheric carbon dioxide (CO2 ) and air temperature affect silicon accumulation in grasses, especially in relation to primary and secondary metabolites. We tested how elevated CO2 (eCO2 ) (+240 ppm) and temperature (eT) (+4°C) affected chemical composition (silicon, phenolics, carbon and nitrogen) and plant growth in eight grass species, either native or exotic to Australia. eCO2 increased phenolic concentrations by 11%, but caused silicon accumulation to decline by 12%. Moreover, declines in silicon occurred mainly in native species (-19%), but remained largely unchanged in exotic species. Conversely, eT increased silicon accumulation in native species (+19%) but decreased silicon accumulation in exotic species (-10%). Silicon and phenolic concentrations were negatively correlated with each other, potentially reflecting a defensive trade-off. Moreover, both defences were negatively correlated with plant mass, compatible with a growth-defence trade-off. Grasses responded in a species-specific manner, suggesting that the relative susceptibility of different species may differ under future climates compared to current species rankings of resource quality. For example, the native Microlaena stipoides was less well defended under eCO2 in terms of both phenolics and silicon, and thus could suffer greater vulnerability to herbivores. To our knowledge, this is the first demonstration of the impacts of eCO2 and eT on silicon accumulation in grasses. We speculate that the greater plasticity in silicon uptake shown by Australian native grasses may be partly a consequence of evolving in a low nutrient and seasonally arid environment.
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Affiliation(s)
- Scott N Johnson
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
| | - Susan E Hartley
- Department of Biology, York Environment and Sustainability Institute, University of York, York, UK
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Barnett KL, Johnson SN, Power SA. Drought negates growth stimulation due to root herbivory in pasture grasses. Oecologia 2018; 188:777-789. [PMID: 30099604 DOI: 10.1007/s00442-018-4244-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 08/04/2018] [Indexed: 10/28/2022]
Abstract
Predicted increases in extreme weather are likely to alter the interactions between organisms within ecosystems. Whilst many studies have investigated the impacts of climate change on aboveground plant-insect interactions, those belowground remain relatively unexplored. Root herbivores can be the dominant taxa in grasslands, potentially altering plant community dynamics. To better predict the impact of climate change on grasslands, we subjected four Australian pasture grasses (Cynodon dactylon, Paspalum dilatatum, Microlaena stipoides and Lolium perenne) to contrasting rainfall regimes [a press drought (i.e. sustained, moderate water stress), a pulse drought (water stress followed by periodic, infrequent deluge event) and a well-watered control], with and without root herbivores; a manual root cutting treatment was also included for comparison. Plant growth, rooting strategy, phenology and biochemistry were measured to evaluate above and belowground treatment responses. Watering treatments had a larger effect on plant productivity than root damage treatments: press drought and pulse drought treatments reduced biomass by 58% and 47%, respectively. Root herbivore damage effects were species dependent and were not always equivalent to root cutting. The combination of pulse drought and root herbivory resulted in increased root:shoot ratios for both P. dilatatum and L. perenne, as well as decreased biomass and delayed flowering time for P. dilatatum. Plant biomass responses to root damage were greatest under well-watered conditions; however, root damage also delayed or prevented investment in reproduction in at least one species. Our findings highlight the important role of soil-dwelling invertebrates for forecasting growth responses of grassland communities to future rainfall regime changes.
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Affiliation(s)
- Kirk L Barnett
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia.
| | - Scott N Johnson
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
| | - Sally A Power
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
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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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Johnson SN, Ryalls JMW, Gherlenda AN, Frew A, Hartley SE. Benefits from Below: Silicon Supplementation Maintains Legume Productivity under Predicted Climate Change Scenarios. FRONTIERS IN PLANT SCIENCE 2018; 9:202. [PMID: 29527218 PMCID: PMC5829608 DOI: 10.3389/fpls.2018.00202] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Accepted: 02/02/2018] [Indexed: 05/09/2023]
Abstract
Many studies demonstrate that elevated atmospheric carbon dioxide concentrations (eCO2) can promote root nodulation and biological nitrogen fixation (BNF) in legumes such as lucerne (Medicago sativa). But when elevated temperature (eT) conditions are applied in tandem with eCO2, a more realistic scenario for future climate change, the positive effects of eCO2 on nodulation and BNF in M. sativa are often much reduced. Silicon (Si) supplementation of M. sativa has also been reported to promote root nodulation and BNF, so could potentially restore the positive effects of eCO2 under eT. Increased nitrogen availability, however, could also increase host suitability for aphid pests, potentially negating any benefit. We applied eCO2 (+240 ppm) and eT (+4°C), separately and in combination, to M. sativa growing in Si supplemented (Si+) and un-supplemented soil (Si-) to determine whether Si moderated the effects of eCO2 and eT. Plants were either inoculated with the aphid Acyrthosiphon pisum or insect-free. In Si- soils, eCO2 stimulated plant growth by 67% and nodulation by 42%, respectively, whereas eT reduced these parameters by 26 and 48%, respectively. Aphids broadly mirrored these effects on Si- plants, increasing colonization rates under eCO2 and performing much worse (reduced abundance and colonization) under eT when compared to ambient conditions, confirming our hypothesized link between root nodulation, plant growth, and pest performance. Examined across all CO2 and temperature regimes, Si supplementation promoted plant growth (+93%), and root nodulation (+50%). A. pisum abundance declined sharply under eT conditions and was largely unaffected by Si supplementation. In conclusion, supplementing M. sativa with Si had consistent positive effects on plant growth and nodulation under different CO2 and temperature scenarios. These findings offer potential for using Si supplementation to maintain legume productivity under predicted climate change scenarios without making legumes more susceptible to insect pests.
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Affiliation(s)
- Scott N. Johnson
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
| | - James M. W. Ryalls
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
| | - Andrew N. Gherlenda
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
| | - Adam Frew
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
| | - Susan E. Hartley
- York Environmental Sustainability Institute, Department of Biology, University of York, York, United Kingdom
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