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Formenti L, Iwanycki Ahlstrand N, Hassemer G, Glauser G, van den Hoogen J, Rønsted N, van der Heijden M, Crowther TW, Rasmann S. Macroevolutionary decline in mycorrhizal colonization and chemical defense responsiveness to mycorrhization. iScience 2023; 26:106632. [PMID: 37168575 PMCID: PMC10165190 DOI: 10.1016/j.isci.2023.106632] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 01/02/2023] [Accepted: 04/04/2023] [Indexed: 05/13/2023] Open
Abstract
Arbuscular mycorrhizal fungi (AMF) have evolved associations with roots of 60% plant species, but the net benefit for plants vary broadly from mutualism to parasitism. Yet, we lack a general understanding of the evolutionary and ecological forces driving such variation. To this end, we conducted a comparative phylogenetic experiment with 24 species of Plantago, encompassing worldwide distribution, to address the effect of evolutionary history and environment on plant growth and chemical defenses in response to AMF colonization. We demonstrate that different species within one plant genus vary greatly in their ability to associate with AMF, and that AMF arbuscule colonization intensity decreases monotonically with increasing phylogenetic branch length, but not with concomitant changes in pedological and climatic conditions across species. Moreover, we demonstrate that species with the highest colonization levels are also those that change their defensive chemistry the least. We propose that the costs imposed by high AMF colonization in terms of reduced changes in secondary chemistry might drive the observed macroevolutionary decline in mycorrhization.
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Affiliation(s)
- Ludovico Formenti
- Laboratory of Functional Ecology, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
- Institute of Ecology and Evolution, Terrestrial ecology, University of Bern, Bern, Switzerland
| | - Natalie Iwanycki Ahlstrand
- Natural History Museum of Denmark, University of Copenhagen, Øster Voldgade 5–7, 1350 Copenhagen, Denmark
| | - Gustavo Hassemer
- Natural History Museum of Denmark, University of Copenhagen, Øster Voldgade 5–7, 1350 Copenhagen, Denmark
| | - Gaëtan Glauser
- Neuchâtel Platform of Analytical Chemistry (NPAC), University of Neuchâtel, Neuchâtel, Switzerland
| | - Johan van den Hoogen
- Department of Environmental Systems Science, Institute of Integrative Biology, ETH Zürich, Zürich, Switzerland
| | - Nina Rønsted
- Natural History Museum of Denmark, University of Copenhagen, Øster Voldgade 5–7, 1350 Copenhagen, Denmark
- National Tropical Botanical Garden, Kalaheo, HI 96741, USA
| | - Marcel van der Heijden
- Plant-Soil Interactions, Institute for Sustainability Sciences, Agroscope, 8046 Zürich, Switzerland
| | - Thomas W. Crowther
- Department of Environmental Systems Science, Institute of Integrative Biology, ETH Zürich, Zürich, Switzerland
| | - Sergio Rasmann
- Laboratory of Functional Ecology, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
- Corresponding author
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Malik RJ, Bever JD. Enriched CO 2 and Root-Associated Fungi (Mycorrhizae) Yield Inverse Effects on Plant Mass and Root Morphology in Six Asclepias Species. PLANTS (BASEL, SWITZERLAND) 2021; 10:2474. [PMID: 34834836 PMCID: PMC8617772 DOI: 10.3390/plants10112474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 11/02/2021] [Accepted: 11/04/2021] [Indexed: 11/16/2022]
Abstract
While milkweeds (Asclepias spp.) are important for sustaining biodiversity in marginal ecosystems, CO2 flux may afflict Asclepias species and cause detriment to native communities. Negative CO2-induced effects may be mitigated through mycorrhizal associations. In this study, we sought to determine how mycorrhizae interacts with CO2 to influence Asclepias biomass and root morphology. A broad range of Asclepias species (n = 6) were chosen for this study, including four tap-root species (A. sullivantii, A. syriaca, A. tuberosa, and A. viridis) and two fibrous root species (A. incarnata and A. verticillata). Collectively, the six Asclepias species were manipulated under a 2 × 2 full-factorial design that featured two mycorrhizal levels (-/+ mycorrhizae) and two CO2 levels (ambient and enriched (i.e., 3.5× ambient)). After a duration of 10 months, Asclepias responses were assessed as whole dry weight (i.e., biomass) and relative transportive root. Relative transportive root is the percent difference in the diameter of highest order root (transportive root) versus that of first-order absorptive roots. Results revealed an asymmetrical response, as mycorrhizae increased Asclepias biomass by ~12-fold, while enriched CO2 decreased biomass by about 25%. CO2 did not impact relative transportive roots, but mycorrhizae increased root organ's response by more than 20%. Interactions with CO2 and mycorrhizae were observed for both biomass and root morphology (i.e., relative transportive root). A gene associated with CO2 fixation (rbcL) revealed that the two fibrous root species formed a phylogenetic clade that was distant from the four tap-root species. The effect of mycorrhizae was most profound in tap-root systems, as mycorrhizae modified the highest order root into tuber-like structures. A strong positive correlation was observed with biomass and relative transportive root. This study elucidates the interplay with roots, mycorrhizae, and CO2, while providing a potential pathway for mycorrhizae to ameliorate CO2 induced effects.
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Affiliation(s)
- Rondy J. Malik
- Department of Ecology and Evolutionary Biology, Kansas Biological Survey, 2101 Constant Ave, Lawrence, KS 66045, USA;
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Potts AS, Hunter MD. Unraveling the roles of genotype and environment in the expression of plant defense phenotypes. Ecol Evol 2021; 11:8542-8561. [PMID: 34257915 PMCID: PMC8258211 DOI: 10.1002/ece3.7639] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 04/06/2021] [Indexed: 11/09/2022] Open
Abstract
Phenotypic variability results from interactions between genotype and environment and is a major driver of ecological and evolutionary interactions. Measuring the relative contributions of genetic variation, the environment, and their interaction to phenotypic variation remains a fundamental goal of evolutionary ecology.In this study, we assess the question: How do genetic variation and local environmental conditions interact to influence phenotype within a single population? We explored this question using seed from a single population of common milkweed, Asclepias syriaca, in northern Michigan. We first measured resistance and resistance traits of 14 maternal lines in two common garden experiments (field and greenhouse) to detect genetic variation within the population. We carried out a reciprocal transplant experiment with three of these maternal lines to assess effects of local environment on phenotype. Finally, we compared the phenotypic traits measured in our experiments with the phenotypic traits of the naturally growing maternal genets to be able to compare relative effect of genetic and environmental variation on naturally occurring phenotypic variation. We measured defoliation levels, arthropod abundances, foliar cardenolide concentrations, foliar latex exudation, foliar carbon and nitrogen concentrations, and plant growth.We found a striking lack of correlation in trait expression of the maternal lines between the common gardens, or between the common gardens and the naturally growing maternal genets, suggesting that environment plays a larger role in phenotypic trait variation of this population. We found evidence of significant genotype-by-environment interactions for all traits except foliar concentrations of nitrogen and cardenolide. Milkweed resistance to chewing herbivores was associated more strongly with the growing environment. We observed no variation in foliar cardenolide concentrations among maternal lines but did observe variation among maternal lines in foliar latex exudation.Overall, our data reveal powerful genotype-by-environment interactions on the expression of most resistance traits in milkweed.
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Affiliation(s)
- Abigail S. Potts
- Department of Ecology & Evolutionary BiologyUniversity of MichiganAnn ArborMIUSA
| | - Mark D. Hunter
- Department of Ecology & Evolutionary BiologyUniversity of MichiganAnn ArborMIUSA
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He E, Agrawal AA. Clonal versus non-clonal milkweeds ( Asclepias spp.) respond differently to stem damage, affecting oviposition by monarch butterflies. PeerJ 2020; 8:e10296. [PMID: 33194443 PMCID: PMC7646301 DOI: 10.7717/peerj.10296] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 10/13/2020] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND Oviposition decisions are critical to the fitness of herbivorous insects and are often impacted by the availability and condition of host plants. Monarch butterflies (Danaus plexippus) rely on milkweeds (Asclepias spp.) for egg-laying and as food for larvae. Previous work has shown that monarchs prefer to oviposit on recently regrown plant tissues (after removal of above-ground biomass) while larvae grow poorly on plants previously damaged by insects. We hypothesized that these effects may depend on the life-history strategy of plants, as clonal and non-clonal milkweed species differ in resource allocation and defense strategies. METHODOLOGY/PRINCIPAL FINDINGS We first confirmed butterfly preference for regrown tissue in a field survey of paired mowed and unmowed plots of the common milkweed A. syriaca. We then experimentally studied the effects of plant damage (comparing undamaged controls to plants clipped and regrown, or damaged by insects) on oviposition choice, larval performance, and leaf quality of two closely related clonal and non-clonal species pairs: (1) A. syriaca and A. tuberosa, and (2) A. verticillata and A. incarnata. Clonal and non-clonal species displayed different responses to plant damage, impacting the proportions of eggs laid on plants. Clonal species had similar mean proportions of eggs on regrown and control plants (≈35-40% each), but fewer on insect-damaged plants (≈20%). Meanwhile non-clonal species had similar oviposition on insect-damaged and control plants (20-30% each) but more eggs on regrown plants (40-60%). Trait analyses showed reduced defenses in regrown plants and we found some evidence, although variable, for negative effects of insect damage on subsequent larval performance. CONCLUSIONS/SIGNIFICANCE Overall, non-clonal species are more susceptible and preferred by monarch butterflies following clipping, while clonal species show tolerance to clipping and induced defense to insect herbivory. These results have implications for monarch conservation strategies that involve milkweed habitat management by mowing. More generally, plant life-history may mediate growth and defense strategies, explaining species-level variation in responses to different types of damage.
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Affiliation(s)
- Elise He
- Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, USA
| | - Anurag A. Agrawal
- Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, USA
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Bakacsy L, Bagi I. Survival and regeneration ability of clonal common milkweed (Asclepias syriaca L.) after a single herbicide treatment in natural open sand grasslands. Sci Rep 2020; 10:14222. [PMID: 32848181 PMCID: PMC7450053 DOI: 10.1038/s41598-020-71202-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Accepted: 08/10/2020] [Indexed: 12/04/2022] Open
Abstract
Invasive species are a major threat to biodiversity, human health, and economies worldwide. Clonal growth is a common ability of most invasive plants. The clonal common milkweed Asclepias syriaca L. is the most widespread invasive species in Pannonic sand grasslands. Despite of being an invader in disturbed semi-natural vegetation, this plant prefers agricultural fields or plantations. Herbicide treatment could be one of the most cost-effective and efficient methods for controlling the extended stands of milkweed in both agricultural and protected areas. The invasion of milkweed stand was monitored from 2011 to 2017 in a strictly protected UNESCO biosphere reserve in Hungary, and a single herbicide treatment was applied in May 2014. This single treatment was successful only in a short-term but not in a long-term period, as the number of milkweed shoots decreased following herbicide treatment. The herbicide translocation by rhizomatic roots induced the damage of dormant bud banks. The surviving buds developing shoots, growth of the milkweed stand showed a slow regeneration for a longer-term period. We concluded that the successful control of milkweed after herbicide treatment depends on repeated management of treated areas to suppress further spreading during subsequent seasons.
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Affiliation(s)
- László Bakacsy
- Department of Plant Biology, Institute of Biology, Faculty of Science and Informatics, University of Szeged, Szeged, 6726, Hungary.
| | - István Bagi
- Department of Plant Biology, Institute of Biology, Faculty of Science and Informatics, University of Szeged, Szeged, 6726, Hungary
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Agrawal AA, Hastings AP. Trade-offs constrain the evolution of an inducible defense within but not between plant species. Ecology 2019; 100:e02857. [PMID: 31365759 DOI: 10.1002/ecy.2857] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 07/13/2019] [Accepted: 07/22/2019] [Indexed: 11/05/2022]
Abstract
Inducible defense is a common form of phenotypic plasticity, and inducibility (change in defense after herbivore attack) has long been predicted to trade off with constitutive (or baseline) defense to manage resource allocation. Although such trade-offs likely constrain evolution within species, the extent to which they influence divergence among species is unresolved. We studied cardenolide toxins among genetic families in eight North American Asclepias species, spanning the full range of defense in the genus. Using common environment experiments and chemical assays, we report a consistent trade-off (negative genetic correlation) between concentrations of constitutive cardenolides and their inducibility within each species. However, no trade-off was found in a phylogenetic analysis across species. To investigate factors driving differences in defense allocation among species we used latitude as a proxy for growing season and herbivore pressure and found that divergence into lower latitudes resulted in evolution of higher cardenolides overall. Next we used an enzymatic assay of the cellular target of cardenolides (sodium-potassium ATPase) and confirm that higher cardenolides resulted in stronger toxicity to a sensitive species, but not to specialized monarch butterflies. Thus, plant speciation into biogeographic regions with alternative resources or pest pressure resulted in the macroevolution of cardenolide defense, especially against unspecialized herbivores. Nonetheless, trade-offs persist in the extent to which this defense is allocated constitutively or is inducible among genotypes within each species.
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Affiliation(s)
- Anurag A Agrawal
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, New York, 14853, USA.,Department of Entomology, Cornell University, Ithaca, New York, 14853, USA
| | - Amy P Hastings
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, New York, 14853, USA
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Kergunteuil A, Humair L, Münzbergová Z, Rasmann S. Plant adaptation to different climates shapes the strengths of chemically mediated tritrophic interactions. Funct Ecol 2019. [DOI: 10.1111/1365-2435.13396] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- Alan Kergunteuil
- Functional Ecology Laboratory, Institute of Biology University of Neuchâtel Neuchâtel Switzerland
| | - Lauréline Humair
- Functional Ecology Laboratory, Institute of Biology University of Neuchâtel Neuchâtel Switzerland
| | - Zuzana Münzbergová
- Department of Botany, Faculty of Science Charles University Prague Czech Republic
- Institute of Botany Czech Academy of Sciences Průhonice Czech Republic
| | - Sergio Rasmann
- Functional Ecology Laboratory, Institute of Biology University of Neuchâtel Neuchâtel Switzerland
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Hahn PG, Agrawal AA, Sussman KI, Maron JL. Population Variation, Environmental Gradients, and the Evolutionary Ecology of Plant Defense against Herbivory. Am Nat 2018; 193:20-34. [PMID: 30624107 DOI: 10.1086/700838] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
A central tenet of plant defense theory is that adaptation to the abiotic environment sets the template for defense strategies, imposing a trade-off between plant growth and defense. Yet this trade-off, commonly found among species occupying divergent resource environments, may not occur across populations of single species. We hypothesized that more favorable climates and higher levels of herbivory would lead to increases in growth and defense across plant populations. We evaluated whether plant growth and defense traits covaried across 18 populations of showy milkweed (Asclepias speciosa) inhabiting an east-west climate gradient spanning 25° of longitude. A suite of traits impacting defense (e.g., latex, cardenolides), growth (e.g., size), or both (e.g., specific leaf area [SLA], trichomes) were measured in natural populations and in a common garden, allowing us to evaluate plastic and genetically based variation in these traits. In natural populations, herbivore pressure increased toward warmer sites with longer growing seasons. Growth and defense traits showed strong clinal patterns and were positively correlated. In a common garden, clines with climatic origin were recapitulated only for defense traits. Correlations between growth and defense traits were also weaker and more negative in the common garden than in the natural populations. Thus, our data suggest that climatically favorable sites likely facilitate the evolution of greater defense at minimal costs to growth, likely because of increased resource acquisition.
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Fishbein M, Straub SCK, Boutte J, Hansen K, Cronn RC, Liston A. Evolution at the tips: Asclepias phylogenomics and new perspectives on leaf surfaces. AMERICAN JOURNAL OF BOTANY 2018; 105:514-524. [PMID: 29693728 DOI: 10.1002/ajb2.1062] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Accepted: 12/19/2017] [Indexed: 06/08/2023]
Abstract
PREMISE OF THE STUDY Leaf surface traits, such as trichome density and wax production, mediate important ecological processes such as anti-herbivory defense and water-use efficiency. We present a phylogenetic analysis of Asclepias plastomes as a framework for analyzing the evolution of trichome density and presence of epicuticular waxes. METHODS We produced a maximum-likelihood phylogeny using plastomes of 103 species of Asclepias. We reconstructed ancestral states and used model comparisons in a likelihood framework to analyze character evolution across Asclepias. KEY RESULTS We resolved the backbone of Asclepias, placing the Sonoran Desert clade and Incarnatae clade as successive sisters to the remaining species. We present novel findings about leaf surface evolution of Asclepias-the ancestor is reconstructed as waxless and sparsely hairy, a macroevolutionary optimal trichome density is supported, and the rate of evolution of trichome density has accelerated. CONCLUSIONS Increased sampling and selection of best-fitting models of evolution provide more resolved and robust estimates of phylogeny and character evolution than obtained in previous studies. Evolutionary inferences are more sensitive to character coding than model selection.
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Affiliation(s)
- Mark Fishbein
- Department of Plant Biology, Ecology & Evolution, Oklahoma State University, Stillwater, OK, 74078, USA
| | - Shannon C K Straub
- Department of Biology, Hobart and William Smith Colleges, Geneva, NY, 14456, USA
| | - Julien Boutte
- Department of Biology, Hobart and William Smith Colleges, Geneva, NY, 14456, USA
| | - Kimberly Hansen
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, 97331, USA
| | - Richard C Cronn
- Pacific Northwest Research Station, USDA Forest Service, Corvallis, OR, 97331, USA
| | - Aaron Liston
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, 97331, USA
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Züst T, Agrawal AA. Trade-Offs Between Plant Growth and Defense Against Insect Herbivory: An Emerging Mechanistic Synthesis. ANNUAL REVIEW OF PLANT BIOLOGY 2017; 68:513-534. [PMID: 28142282 DOI: 10.1146/annurev-arplant-042916-040856] [Citation(s) in RCA: 249] [Impact Index Per Article: 35.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Costs of defense are central to our understanding of interactions between organisms and their environment, and defensive phenotypes of plants have long been considered to be constrained by trade-offs that reflect the allocation of limiting resources. Recent advances in uncovering signal transduction networks have revealed that defense trade-offs are often the result of regulatory "decisions" by the plant, enabling it to fine-tune its phenotype in response to diverse environmental challenges. We place these results in the context of classic studies in ecology and evolutionary biology, and propose a unifying framework for growth-defense trade-offs as a means to study the plant's allocation of limiting resources. Pervasive physiological costs constrain the upper limit to growth and defense traits, but the diversity of selective pressures on plants often favors negative correlations at intermediate trait levels. Despite the ubiquity of underlying costs of defense, the current challenge is using physiological and molecular approaches to predict the conditions where they manifest as detectable trade-offs.
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Affiliation(s)
- Tobias Züst
- Institute of Plant Sciences, University of Bern, 3013 Bern, Switzerland;
| | - Anurag A Agrawal
- Department of Ecology and Evolutionary Biology and Department of Entomology, Cornell University, Ithaca, New York 14853;
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