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Papini A, Luti S, Colzi I, Mazzoli L, Giorni E, Pazzagli L, Gonnelli C. Alternative responses to fungal attack on a metalliferous soil: Phytohormone levels and structural changes in Silene paradoxa L. growing under copper stress. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2019; 286:37-48. [PMID: 31300140 DOI: 10.1016/j.plantsci.2019.06.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 05/29/2019] [Accepted: 06/03/2019] [Indexed: 06/10/2023]
Abstract
In this work, a non-metallicolous and a metallicolous population of S. paradoxa were exposed to copper excess and fungal elicitation, and investigated for phytohormone production and cytological alterations. Under the stress applied separately and in combination, S. paradoxa plants varied phytohormone concentration in a population-specific way, suggesting a different signalling in response to biotic and abiotic stimuli according to the environment of origin. Generally, the stress responses consisted in increased levels of salicylic acid, auxin, and gibberellin in the non-metallicolous population, and of jasmonic and abscisic acid in the metallicolous one. Interestingly, the metallicolous population increased the level of such phytohormones following exposure to the fungal elicitor only in the presence of copper. This alternative hormonal signalling could derive from the incompatibility between the ordinary ROS-mediated response to pathogens and the acquired mechanisms that prevent oxidative stress in the population from the metal-rich soil. Furthermore, stress-induced autophagic phenomena were more evident in the non-metallicolous plants than in the metallicolous ones, suggesting that the adaptation to the metalliferous environment has also affected autophagy intensity and signalling in response to copper excess and fungal elicitation.
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Affiliation(s)
- Alessio Papini
- Department of Biology, Università di Firenze, via Micheli 1, 50121, Firenze, Italy.
| | - Simone Luti
- Department of Biomedical Experimental and Clinical Sciences, Università di Firenze, Viale Morgagni 50, 50134, Firenze, Italy.
| | - Ilaria Colzi
- Department of Biology, Università di Firenze, via Micheli 1, 50121, Firenze, Italy.
| | - Lorenzo Mazzoli
- Department of Biomedical Experimental and Clinical Sciences, Università di Firenze, Viale Morgagni 50, 50134, Firenze, Italy.
| | - Elisabetta Giorni
- Department of Biology, Università di Firenze, via Micheli 1, 50121, Firenze, Italy.
| | - Luigia Pazzagli
- Department of Biomedical Experimental and Clinical Sciences, Università di Firenze, Viale Morgagni 50, 50134, Firenze, Italy.
| | - Cristina Gonnelli
- Department of Biology, Università di Firenze, via Micheli 1, 50121, Firenze, Italy.
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Tian W, Hou C, Ren Z, Wang C, Zhao F, Dahlbeck D, Hu S, Zhang L, Niu Q, Li L, Staskawicz BJ, Luan S. A calmodulin-gated calcium channel links pathogen patterns to plant immunity. Nature 2019; 572:131-135. [PMID: 31316205 DOI: 10.1038/s41586-019-1413-y] [Citation(s) in RCA: 277] [Impact Index Per Article: 55.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2017] [Accepted: 06/25/2019] [Indexed: 11/09/2022]
Abstract
Pathogen-associated molecular patterns (PAMPs) activate innate immunity in both animals and plants. Although calcium has long been recognized as an essential signal for PAMP-triggered immunity in plants, the mechanism of PAMP-induced calcium signalling remains unknown1,2. Here we report that calcium nutrient status is critical for calcium-dependent PAMP-triggered immunity in plants. When calcium supply is sufficient, two genes that encode cyclic nucleotide-gated channel (CNGC) proteins, CNGC2 and CNGC4, are essential for PAMP-induced calcium signalling in Arabidopsis3-7. In a reconstitution system, we find that the CNGC2 and CNGC4 proteins together-but neither alone-assemble into a functional calcium channel that is blocked by calmodulin in the resting state. Upon pathogen attack, the channel is phosphorylated and activated by the effector kinase BOTRYTIS-INDUCED KINASE1 (BIK1) of the pattern-recognition receptor complex, and this triggers an increase in the concentration of cytosolic calcium8-10. The CNGC-mediated calcium entry thus provides a critical link between the pattern-recognition receptor complex and calcium-dependent immunity programs in the PAMP-triggered immunity signalling pathway in plants.
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Affiliation(s)
- Wang Tian
- Department of Plant and Microbial Biology, University of California, Berkeley, CA, USA
| | - Congcong Hou
- Department of Plant and Microbial Biology, University of California, Berkeley, CA, USA
| | - Zhijie Ren
- College of Life Sciences, Capital Normal University, Beijing, China
| | - Chao Wang
- Department of Plant and Microbial Biology, University of California, Berkeley, CA, USA
| | - Fugeng Zhao
- Nanjing University-Nanjing Forestry University Joint Institute for Plant Molecular Biology, College of Life Sciences, Nanjing University, Nanjing, China
| | - Douglas Dahlbeck
- Department of Plant and Microbial Biology, University of California, Berkeley, CA, USA
| | - Songping Hu
- Department of Plant and Microbial Biology, University of California, Berkeley, CA, USA
| | - Liying Zhang
- College of Life Sciences, Capital Normal University, Beijing, China
| | - Qi Niu
- College of Life Sciences, Capital Normal University, Beijing, China
| | - Legong Li
- College of Life Sciences, Capital Normal University, Beijing, China
| | - Brian J Staskawicz
- Department of Plant and Microbial Biology, University of California, Berkeley, CA, USA
| | - Sheng Luan
- Department of Plant and Microbial Biology, University of California, Berkeley, CA, USA.
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3
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Galey ML, van der Ent A, Iqbal MCM, Rajakaruna N. Ultramafic geoecology of South and Southeast Asia. BOTANICAL STUDIES 2017; 58:18. [PMID: 28510201 PMCID: PMC5432931 DOI: 10.1186/s40529-017-0167-9] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Accepted: 03/01/2017] [Indexed: 05/30/2023]
Abstract
Globally, ultramafic outcrops are renowned for hosting floras with high levels of endemism, including plants with specialised adaptations such as nickel or manganese hyperaccumulation. Soils derived from ultramafic regoliths are generally nutrient-deficient, have major cation imbalances, and have concomitant high concentrations of potentially phytotoxic trace elements, especially nickel. The South and Southeast Asian region has the largest surface occurrences of ultramafic regoliths in the world, but the geoecology of these outcrops is still poorly studied despite severe conservation threats. Due to the paucity of systematic plant collections in many areas and the lack of georeferenced herbarium records and databased information, it is not possible to determine the distribution of species, levels of endemism, and the species most threatened. However, site-specific studies provide insights to the ultramafic geoecology of several locations in South and Southeast Asia. The geoecology of tropical ultramafic regions differs substantially from those in temperate regions in that the vegetation at lower elevations is generally tall forest with relatively low levels of endemism. On ultramafic mountaintops, where the combined forces of edaphic and climatic factors intersect, obligate ultramafic species and hyperendemics often occur. Forest clearing, agricultural development, mining, and climate change-related stressors have contributed to rapid and unprecedented loss of ultramafic-associated habitats in the region. The geoecology of the large ultramafic outcrops of Indonesia's Sulawesi, Obi and Halmahera, and many other smaller outcrops in South and Southeast Asia, remains largely unexplored, and should be prioritised for study and conservation.
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Affiliation(s)
- M. L. Galey
- Center for Water and Environment, Natural Resources Research Institute, University of Minnesota, Duluth, MN 55811 USA
| | - A. van der Ent
- Centre for Mined Land Rehabilitation, Sustainable Minerals Institute, The University of Queensland, Brisbane, QLD Australia
- Laboratoire Sols et Environnement, Université de Lorraine-INRA, UMR 1120, Nancy, France
| | - M. C. M. Iqbal
- Plant Biology Laboratory, National Institute of Fundamental Studies, Kandy, 20000 Sri Lanka
| | - N. Rajakaruna
- Biological Sciences Department, California Polytechnic State University, San Luis Obispo, CA 93407 USA
- Unit for Environmental Sciences and Management, North-West University, Potchefstroom, 2520 South Africa
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Borer ET, Laine AL, Seabloom EW. A Multiscale Approach to Plant Disease Using the Metacommunity Concept. ANNUAL REVIEW OF PHYTOPATHOLOGY 2016; 54:397-418. [PMID: 27296140 DOI: 10.1146/annurev-phyto-080615-095959] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Plant disease arises from the interaction of processes occurring at multiple spatial and temporal scales. With new tools such as next-generation sequencing, we are learning about the diversity of microbes circulating within and among plant populations and often coinhabiting host individuals. The proliferation of pathogenic microbes depends on single-species dynamics and multispecies interactions occurring within and among host cells, the spatial organization and genetic landscape of hosts, the frequency and mode of transmission among hosts and host populations, and the abiotic environmental context. Here, we examine empirical evidence from these multiple scales to assess the utility of metacommunity theory, a theoretical framework developed for free-living organisms to further our understanding of and assist in predicting plant-pathogen infection and spread. We suggest that deeper understanding of disease dynamics can arise through the application of this conceptual framework at scales ranging from individual cells to landscapes. In addition, we use this multiscale theoretical perspective to synthesize existing knowledge, generate novel hypotheses, and point toward promising future opportunities for the study of plant pathogens in natural populations.
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Affiliation(s)
- Elizabeth T Borer
- Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, Minnesota 55108; ,
| | - Anna-Liisa Laine
- Centre of Excellence in Metapopulation Biology, Department of Biosciences, University of Helsinki, FI-00014, Finland;
| | - Eric W Seabloom
- Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, Minnesota 55108; ,
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5
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Taiti C, Giorni E, Colzi I, Pignattelli S, Bazihizina N, Buccianti A, Luti S, Pazzagli L, Mancuso S, Gonnelli C. Under fungal attack on a metalliferous soil: ROS or not ROS? Insights from Silene paradoxa L. growing under copper stress. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2016; 210:282-292. [PMID: 26799504 DOI: 10.1016/j.envpol.2015.12.020] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Revised: 12/09/2015] [Accepted: 12/09/2015] [Indexed: 06/05/2023]
Abstract
We investigated how the adaptation to metalliferous environments can influence the plant response to biotic stress. In a metallicolous and a non-metallicolous population of Silene paradoxa the induction of oxidative stress and the production of callose and volatiles were evaluated in the presence of copper and of the PAMP fungal protein cerato-platanin, separately and in combination. Our results showed incompatibility between the ordinary ROS-mediated response to fungal attack and the acquired mechanisms of preventing oxidative stress in the tolerant population. A similar situation was also demonstrated by the sensitive population growing in the presence of copper but, in this case, with a lack of certain responses, such as callose production. In addition, in terms of the joint behaviour of emitted volatiles, multivariate statistics showed that not only did the populations respond differently to the presence of copper or biotic stress, but also that the biotic and abiotic stresses interacted in different ways in the two populations. Our results demonstrated that the same incompatibility of hyperaccumulators in ROS-mediated biotic stress signals also seemed to be exhibited by the excluder metallophyte, but without the advantage of being able to rely on the elemental defence for plant protection from natural enemies.
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Affiliation(s)
- Cosimo Taiti
- Department of Agri-Food and Environmental Science, Università di Firenze, via delle Idee 30, 50019, Sesto Fiorentino, Italy.
| | - Elisabetta Giorni
- Department of Biology, Università di Firenze, via Micheli 1, 50121, Firenze, Italy.
| | - Ilaria Colzi
- Department of Biology, Università di Firenze, via Micheli 1, 50121, Firenze, Italy.
| | - Sara Pignattelli
- Department of Biology, Università di Firenze, via Micheli 1, 50121, Firenze, Italy.
| | - Nadia Bazihizina
- Department of Agri-Food and Environmental Science, Università di Firenze, via delle Idee 30, 50019, Sesto Fiorentino, Italy.
| | - Antonella Buccianti
- Department of Earth Science, Università di Firenze, via La Pira 4, 50121, Firenze, Italy.
| | - Simone Luti
- Department of Biomedical Experimental and Clinical Sciences, Università di Firenze, viale Morgagni 50, 50134, Firenze, Italy.
| | - Luigia Pazzagli
- Department of Biomedical Experimental and Clinical Sciences, Università di Firenze, viale Morgagni 50, 50134, Firenze, Italy.
| | - Stefano Mancuso
- Department of Agri-Food and Environmental Science, Università di Firenze, via delle Idee 30, 50019, Sesto Fiorentino, Italy.
| | - Cristina Gonnelli
- Department of Biology, Università di Firenze, via Micheli 1, 50121, Firenze, Italy.
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Penczykowski RM, Walker E, Soubeyrand S, Laine AL. Linking winter conditions to regional disease dynamics in a wild plant-pathogen metapopulation. THE NEW PHYTOLOGIST 2015; 205:1142-1152. [PMID: 25382661 DOI: 10.1111/nph.13145] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Accepted: 09/25/2014] [Indexed: 06/04/2023]
Abstract
Pathogens are considered to drive ecological and evolutionary dynamics of plant populations, but we lack data measuring the population-level consequences of infection in wild plant-pathogen interactions. Moreover, while it is often assumed that offseason environmental conditions drive seasonal declines in pathogen population size, little is known about how offseason environmental conditions impact the survival of pathogen resting stages, and how critical the offseason is for the next season's epidemic. The fungal pathogen Podosphaera plantaginis persists as a dynamic metapopulation in the large network of Plantago lanceolata host populations. Here, we analyze long-term data to measure the spatial synchrony of epidemics and consequences of infection for over 4000 host populations. Using a theoretical model, we study whether large-scale environmental change could synchronize disease occurrence across the metapopulation. During 2001-2013 exposure to freezing decreased, while pathogen extinction-colonization-persistence rates became more synchronized. Simulations of a theoretical model suggest that increasingly favorable winter conditions for pathogen survival could drive such synchronization. Our data also show that infection decreases host population growth. These results confirm that mild winter conditions increase pathogen overwintering success and thus increase disease prevalence across the metapopulation. Further, we conclude that the pathogen can drive host population growth in the Plantago-Podosphaera system.
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Affiliation(s)
- Rachel M Penczykowski
- Metapopulation Research Group, Department of Biosciences, University of Helsinki, PO Box 65, (Viikinkaari 1), Helsinki, FI-00014, Finland
| | - Emily Walker
- INRA, UR546 Biostatistics and Spatial Processes, 84914, Avignon, France
| | - Samuel Soubeyrand
- INRA, UR546 Biostatistics and Spatial Processes, 84914, Avignon, France
| | - Anna-Liisa Laine
- Metapopulation Research Group, Department of Biosciences, University of Helsinki, PO Box 65, (Viikinkaari 1), Helsinki, FI-00014, Finland
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7
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Domic AI, Camilo GR, Capriles JM. Small-scale Farming and Grazing Reduce Regeneration ofPolylepis tomentella(Rosaceae) in the Semiarid Andes of Bolivia. Biotropica 2013. [DOI: 10.1111/btp.12075] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- Alejandra I. Domic
- Department of Biology; Saint Louis University; Saint Louis MO 63130 U.S.A
- Herbario Nacional de Bolivia; Universidad Mayor de San Andrés; La Paz Bolivia
| | - Gerardo R. Camilo
- Department of Biology; Saint Louis University; Saint Louis MO 63130 U.S.A
| | - José M. Capriles
- Instituto de Alta Investigación; Universidad de Tarapacá; Antofagasta 1520, Casilla 6-D Arica Chile
- Centro de Investigaciones del Hombre en el Desierto (CIHDE); Av. General Velásquez 1775 Arica Chile
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8
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Civitello DJ, Penczykowski RM, Hite JL, Duffy MA, Hall SR. Potassium stimulates fungal epidemics in Daphnia by increasing host and parasite reproduction. Ecology 2013; 94:380-8. [PMID: 23691657 DOI: 10.1890/12-0883.1] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
As natural enemies, parasites can dramatically harm host populations, and even catalyze their decline. Thus, identifying factors that promote disease spread is paramount. Environmental factors can drive epidemics by altering traits involved in disease spread. For example, nutrients (such as nitrogen and phosphorus) can stimulate reproduction of both hosts and parasites or alter rates of disease transmission by stimulating productivity and nutrition of food resources of hosts. Here, we demonstrate nutrient-trait-epidemic connections between the greatly understudied macronutrient potassium (K) and fungal disease (Metschnikowia bicuspidata) in a zooplankton host (Daphnia dentifera). In a three-year survey, epidemics grew larger in lakes with more potassium. In laboratory assays, potassium enrichment of low-K lake water enhanced both host and parasite reproduction. Parameterized with these data, a model predicted that potassium addition catalyzes disease spread. We confirmed this prediction with an experiment in large mesocosms (6000 L) in a low K-lake: potassium enrichment caused larger epidemics in replicated Daphnia populations. Consequently, the model--data combination mechanistically explained the field pattern and revealed a novel ecological role for the nutrient potassium. Furthermore, our findings highlight the need for further development of theory for nutrient limitation of epidemics. Such theory could help to explain heterogeneous eruptions of disease in space, connect these outbreaks to natural or anthropogenic enrichment of ecosystems, predict the ecological consequences of these outbreaks, and reveal novel strategies for disease management.
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Affiliation(s)
- David J Civitello
- Department of Biology, Indiana University, Bloomington, Indiana 47405, USA.
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9
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Verhoeven KJF, Biere A. Geographic parthenogenesis and plant-enemy interactions in the common dandelion. BMC Evol Biol 2013; 13:23. [PMID: 23356700 PMCID: PMC3562243 DOI: 10.1186/1471-2148-13-23] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2012] [Accepted: 01/16/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Many species with sexual and asexual variants show a pattern of geographic parthenogenesis where asexuals have broader and higher-latitude distribution than sexuals. Because sexual reproduction is often considered a costly evolutionary strategy that is advantageous in the face of selection by coevolving pests and pathogens, one possible explanation for geographic parthenogenesis is that populations at higher latitudes are exposed to fewer pests and pathogens. We tested this hypothesis in the common dandelion (Taraxacum officinale), a species with well-established geographic parthenogenesis, by screening prevalence and effects of several specialized pests and pathogens in natural dandelion populations. RESULTS We did a population survey of 18 dandelion populations along a geographic transect that ranged from the area where sexual and asexual dandelions co-occur northward into the area where only asexuals occur. In addition we used four southern and four northern populations in a 8x8 cross-inoculation greenhouse experiment in which plants were exposed experimentally to each other's natural field soil microbial communities. The cross-inoculation experiment indicated a higher pathogenicity of soil microbial communities from the southern, mostly sexual, populations compared to soil microbial communities from the northern asexual populations. Northern dandelion populations also showed reduced infestation by a specialized seed-eating weevil. A similar trend of reduced rust fungus infection in northern populations was observed but this trend was not statistically significant. CONCLUSIONS The prevalence of pests and pathogens decreased along the south-to-north axis of geographic parthenogenesis. This highlights the potential of biotic interactions in shaping patterns of geographic parthenogenesis.
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Affiliation(s)
- Koen JF Verhoeven
- Department of Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Droevendaalsesteeg 10, Wageningen, 6708 PB, The Netherlands
| | - Arjen Biere
- Department of Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Droevendaalsesteeg 10, Wageningen, 6708 PB, The Netherlands
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10
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Fernandez-Going BM, Anacker BL, Harrison SP. Temporal variability in California grasslands: soil type and species functional traits mediate response to precipitation. Ecology 2012; 93:2104-14. [PMID: 23094382 DOI: 10.1890/11-2003.1] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Plant communities on infertile soils may be relatively resistant to climatic variation if species in these communities have "stress-tolerant" functional traits that limit their ability to respond to climate. Alternatively, such communities may be more sensitive to climatic variation if their relatively sparse vegetative cover exposes species to more extreme changes in factors such as temperature or wind. We compared temporal variability in species richness and composition over 10 years between grasslands on infertile serpentine and "normal" sedimentary soils. Variability in species richness and species composition tracked mean annual precipitation on both soils, but variability was lower in serpentine grasslands. Communities on serpentine had lower functional diversity and had species with more "stress-tolerant" traits than non-serpentine communities (i.e., shorter stature, lower specific leaf area, and lower leaf area). Within and between soils, variability in species richness and temporal turnover were lower in communities scoring as more stress tolerant on a multivariate index of these traits; however, community variability was unrelated to functional diversity. Within 41 species found commonly on both soils, variability in occurrence and cover were also lower on serpentine soils, even though intraspecific trait differences between soils were minimal; this suggests a direct effect of soil type on species variability in addition to the indirect, trait-mediated effect. Communities with higher biomass had higher annual variability in species occurrence and cover. Our results suggest that infertile soils reduce compositional variability indirectly by selecting for stress-tolerant traits and directly by limiting productivity. We conclude that communities on infertile soils may respond more conservatively to predicted changes in precipitation, including increased variability, than communities on soils of normal fertility.
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Affiliation(s)
- B M Fernandez-Going
- Department of Environmental Science and Policy, University of California, One Shields Drive, Davis, California 95616, USA.
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11
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Salama N, van den Bosch F, Edwards G, Heard M, Jeger M. Population dynamics of a non-cultivated biennial plant Tragopogon pratensis infected by the autoecious demicyclic rust fungus Puccinia hysterium. FUNGAL ECOL 2012. [DOI: 10.1016/j.funeco.2011.12.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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12
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Swope SM, Stein IR. Soil type mediates indirect interactions between Centaurea solstitialis and its biocontrol agents. Biol Invasions 2012. [DOI: 10.1007/s10530-012-0181-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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13
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Andonian K, Hierro JL, Khetsuriani L, Becerra P, Janoyan G, Villarreal D, Cavieres L, Fox LR, Callaway RM. Range-expanding populations of a globally introduced weed experience negative plant-soil feedbacks. PLoS One 2011; 6:e20117. [PMID: 21629781 PMCID: PMC3100334 DOI: 10.1371/journal.pone.0020117] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2010] [Accepted: 04/25/2011] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Biological invasions are fundamentally biogeographic processes that occur over large spatial scales. Interactions with soil microbes can have strong impacts on plant invasions, but how these interactions vary among areas where introduced species are highly invasive vs. naturalized is still unknown. In this study, we examined biogeographic variation in plant-soil microbe interactions of a globally invasive weed, Centaurea solstitialis (yellow starthistle). We addressed the following questions (1) Is Centaurea released from natural enemy pressure from soil microbes in introduced regions? and (2) Is variation in plant-soil feedbacks associated with variation in Centaurea's invasive success? METHODOLOGY/PRINCIPAL FINDINGS We conducted greenhouse experiments using soils and seeds collected from native Eurasian populations and introduced populations spanning North and South America where Centaurea is highly invasive and noninvasive. Soil microbes had pervasive negative effects in all regions, although the magnitude of their effect varied among regions. These patterns were not unequivocally congruent with the enemy release hypothesis. Surprisingly, we also found that Centaurea generated strong negative feedbacks in regions where it is the most invasive, while it generated neutral plant-soil feedbacks where it is noninvasive. CONCLUSIONS/SIGNIFICANCE Recent studies have found reduced below-ground enemy attack and more positive plant-soil feedbacks in range-expanding plant populations, but we found increased negative effects of soil microbes in range-expanding Centaurea populations. While such negative feedbacks may limit the long-term persistence of invasive plants, such feedbacks may also contribute to the success of invasions, either by having disproportionately negative impacts on competing species, or by yielding relatively better growth in uncolonized areas that would encourage lateral spread. Enemy release from soil-borne pathogens is not sufficient to explain the success of this weed in such different regions. The biogeographic variation in soil-microbe effects indicates that different mechanisms may operate on this species in different regions, thus establishing geographic mosaics of species interactions that contribute to variation in invasion success.
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Affiliation(s)
- Krikor Andonian
- Department of Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, California, United States of America.
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14
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Springer YP. Do extreme environments provide a refuge from pathogens? A phylogenetic test using serpentine flax. AMERICAN JOURNAL OF BOTANY 2009; 96:2010-2021. [PMID: 21622321 DOI: 10.3732/ajb.0900047] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Abiotically extreme environments are often associated with physiologically stressful conditions, small, low-density populations, and depauperate flora and fauna relative to more benign settings. A possible consequence of this may be that organisms that occupy these stressful habitats receive fitness benefits associated with reductions in the frequency and/or intensity of antagonistic species interactions. I investigated a particular form of this effect, formalized as the "pathogen refuge hypothesis," through a study of 13 species of wild flax that grow on stressful serpentine soils and are often infected by a pathogenic fungal rust. The host species vary in the degree of their serpentine association: some specialize on extreme serpentine soils, while others are generalists that occur on soils with a wide range of serpentine influence. Phylogenetically explicit analyses of soil chemistry and field-measured disease levels indicated that rust disease was significantly less frequent and severe in flax populations growing in more stressful, low-calcium serpentine soils. These findings may help to explain the persistence of extremophile species in habitats where stressful physical conditions often impose strong autecological fitness costs on associated organisms. Ancestral state reconstruction of serpentine soil tolerance (approximated using soil calcium concentrations) suggested that the ability to tolerate extreme serpentine soils may have evolved multiple times within the focal genus.
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Affiliation(s)
- Yuri P Springer
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, A316 Earth and Marine Sciences Building, Santa Cruz, California 95064 USA
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