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Claassens R, Venter SN, Beukes CW, Stępkowski T, Chan WY, Steenkamp ET. Bradyrhizobium xenonodulans sp. nov. isolated from nodules of Australian Acacia species invasive to South Africa. Syst Appl Microbiol 2023; 46:126452. [PMID: 37634485 DOI: 10.1016/j.syapm.2023.126452] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 08/08/2023] [Accepted: 08/10/2023] [Indexed: 08/29/2023]
Abstract
A genealogical concordance approach was used to delineate strains isolated from Acacia dealbata and Acacia mearnsii root nodules in South Africa. These isolates form part of Bradyrhizobium based on 16S rRNA sequence similarity. Phylogenetic analysis of six housekeeping genes (atpD, dnaK, glnII, gyrB, recA and rpoB) confirmed that these isolates represent a novel species, while pairwise average nucleotide identity (ANIb) calculations with the closest type strains (B. cosmicum 58S1T, B. betae PL7HG1T, B. ganzhouense CCBAU 51670 T, B. cytisi CTAW11T and B. rifense CTAW71T) resulted in values well below 95-96%. We further performed phenotypic tests which revealed that there are high levels of intraspecies variation, while an additional analysis of the nodA and nifD loci indicated that the symbiotic loci of the strains are closely related to those of Bradyrhizobium isolates with an Australian origin. Strain 14ABT (=LMG 31415 T = SARCC-753 T) is designated as the type strain of the novel species for which we propose the name Bradyrhizobium xenonodulans sp. nov.
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Affiliation(s)
- Ricu Claassens
- Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria 0002, Gauteng, South Africa
| | - Stephanus N Venter
- Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria 0002, Gauteng, South Africa
| | | | - Tomasz Stępkowski
- Department of Biochemistry and Microbiology, Institute of Biology, Warsaw University of Life Sciences (SGGW), Poland
| | - Wai Y Chan
- Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria 0002, Gauteng, South Africa; Right to Care, Centurion, Gauteng, South Africa
| | - Emma T Steenkamp
- Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria 0002, Gauteng, South Africa.
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Le Roux JJ, Leishman MR, Geraghty DM, Manea A. Rewiring critical plant-soil microbial interactions to assist ecological restoration. AMERICAN JOURNAL OF BOTANY 2023; 110:e16228. [PMID: 37708536 DOI: 10.1002/ajb2.16228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Revised: 07/12/2023] [Accepted: 07/13/2023] [Indexed: 09/16/2023]
Affiliation(s)
| | | | - Dylan M Geraghty
- School of Natural Sciences, Macquarie University, Sydney, Australia
| | - Anthony Manea
- School of Natural Sciences, Macquarie University, Sydney, Australia
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3
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Warrington S, Ellis AG, Keet JH, Le Roux JJ. How does familiarity in rhizobial interactions impact the performance of invasive and native legumes? NEOBIOTA 2022. [DOI: 10.3897/neobiota.72.79620] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Mutualisms can be disrupted when non-native plants are introduced into novel environments, potentially impacting their establishment success. Introduced species can reassemble mutualisms by forming novel associations with resident biota or by maintaining familiar associations when they are co-introduced with their mutualists. Invasive Australian Acacia species in South Africa have formed nitrogen-fixing rhizobium mutualisms using both pathways.
Here we examined the contributions of novel vs familiar rhizobial associations to the performance of Acacia saligna across different soils within South Africa’s Core Cape Subregion (CCR), and the concomitant impacts of exotic rhizobia on the endemic legume, Psoralea pinnata. We grew each legume with and without Australian Bradyrhizobium strains across various CCR soil types in a glasshouse. We identified root nodule rhizobium communities associating with seedlings grown in each treatment combination using next-generation sequencing (NGS) techniques.
Our results show that different CCR soils affected growth performances of seedlings for both species while the addition of Australian bradyrhizobia affected growth performances of A. saligna, but not P. pinnata. NGS data revealed that each legume associated mostly with their familiar rhizobial partners, regardless of soil conditions or inoculum treatment. Acacia saligna predominantly associated with Australian bradyrhizobia, even when grown in soils without inoculum, while P. pinnata largely associated with native South African Mesorhizobium strains.
Our study suggests that exotic Australian bradyrhizobia are already present and widespread in pristine CCR soils, and that mutualist limitation is not an impediment to further acacia invasion in the region. The ability of P. pinnata to sanction Australian Bradyrhizobium strains suggests that this species may be a good candidate for restoration efforts following the removal of acacias in CCR habitats.
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Tsiknia M, Tsikou D, Papadopoulou KK, Ehaliotis C. Multi-species relationships in legume roots: From pairwise legume-symbiont interactions to the plant - microbiome - soil continuum. FEMS Microbiol Ecol 2021; 97:5957530. [PMID: 33155054 DOI: 10.1093/femsec/fiaa222] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Accepted: 11/03/2020] [Indexed: 01/02/2023] Open
Abstract
Mutualistic relationships of legume plants with, either bacteria (like rhizobia) or fungi (like arbuscular mycorrhizal fungi), have been investigated intensively, usually as bi-partite interactions. However, diverse symbiotic interactions take place simultaneously or sequentially under field conditions. Their collective, but not additive, contribution to plant growth and performance remains hard to predict, and appears to be furthermore affected by crop species and genotype, non-symbiotic microbial interactions and environmental variables. The challenge is: (i) to unravel the complex overlapping mechanisms that operate between the microbial symbionts as well as between them, their hosts and the rhizosphere (ii) to understand the dynamics of the respective mechanisms in evolutionary and ecological terms. The target for agriculture, food security and the environment, is to use this insight as a solid basis for developing new integrated technologies, practices and strategies for the efficient use of beneficial microbes in legumes and other plants. We review recent advances in our understanding of the symbiotic interactions in legumes roots brought about with the aid of molecular and bioinformatics tools. We go through single symbiont-host interactions, proceed to tripartite symbiont-host interactions, appraise interactions of symbiotic and associative microbiomes with plants in the root-rhizoplane-soil continuum of habitats and end up by examining attempts to validate community ecology principles in the legume-microbe-soil biosystem.
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Affiliation(s)
- Myrto Tsiknia
- Soils and Soil Chemistry Lab, Department of Natural Resources and Agricultural Engineering, Agricultural University of Athens, Iera Odos 75 st., Athens 11855, Greece
| | - Daniela Tsikou
- Laboratory of Plant and Environmental Biotechnology, Department of Biochemistry and Biotechnology, University of Thessaly, Biopolis, 41500 Larissa, Greece
| | - Kalliope K Papadopoulou
- Laboratory of Plant and Environmental Biotechnology, Department of Biochemistry and Biotechnology, University of Thessaly, Biopolis, 41500 Larissa, Greece
| | - Constantinos Ehaliotis
- Soils and Soil Chemistry Lab, Department of Natural Resources and Agricultural Engineering, Agricultural University of Athens, Iera Odos 75 st., Athens 11855, Greece
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Amplicon Sequencing-Based Bipartite Network Analysis Confirms a High Degree of Specialization and Modularity for Fungi and Prokaryotes in Deadwood. mSphere 2021; 6:6/1/e00856-20. [PMID: 33441408 PMCID: PMC7845612 DOI: 10.1128/msphere.00856-20] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
Abstract
Deadwood is important for our forest ecosystems. It feeds and houses many organisms, e.g., fungi and prokaryotes, with many different species contributing to its decomposition and nutrient cycling. Fungi and prokaryotes are dominant colonizers of wood and mediate its decomposition. Much progress has been achieved to unravel these communities and link them to specific wood properties. However, comparative studies considering both groups of organisms and assessing their relationships to wood resources are largely missing. Bipartite interaction networks provide an opportunity to investigate this colonizer-resource relationship more in detail and aim to directly compare results between different biotic groups. The main questions were as follows. Are network structures reflecting the trophic relationship between fungal and prokaryotic colonizers and their resources? If so, do they reflect the critical role of these groups, especially that of fungi, during decomposition? We used amplicon sequencing data to analyze fungal and prokaryotic interaction networks from deadwood of 13 temperate tree species at an early to middle stage of decomposition. Several diversity- and specialization-related indices were determined and the observed network structures were related to intrinsic wood traits. We hypothesized nonrandom bipartite networks for both groups and a higher degree of specialization for fungi, as they are the key players in wood decomposition. The results reveal highly modular and specialized interaction networks for both groups of organisms, demonstrating that many fungi and prokaryotes are resource-specific colonizers. However, as the level of specialization of fungi significantly surpassed that of prokaryotes, our findings reflect the strong association between fungi and their host. Our novel approach shows that the application of bipartite interaction networks is a useful tool to explore, quantify, and compare the deadwood-colonizers relationship based on sequencing data. IMPORTANCE Deadwood is important for our forest ecosystems. It feeds and houses many organisms, e.g., fungi and prokaryotes, with many different species contributing to its decomposition and nutrient cycling. The aim of this study was to explore and quantify the relationship between these two main wood-inhabiting organism groups and their corresponding host trees. Two independent DNA-based amplicon sequencing data sets (fungi and prokaryotes) were analyzed via bipartite interaction networks. The links in the networks represent the interactions between the deadwood colonizers and their deadwood hosts. The networks allowed us to analyze whether many colonizing species interact mostly with a restricted number of deadwood tree species, so-called specialization. Our results demonstrate that many prokaryotes and fungi are resource-specific colonizers. The direct comparison between both groups revealed significantly higher specialization values for fungi, emphasizing their strong association to respective host trees, which reflects their dominant role in exploiting this resource.
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Yao H, Sun X, He C, Li XC, Guo LD. Host identity is more important in structuring bacterial epiphytes than endophytes in a tropical mangrove forest. FEMS Microbiol Ecol 2020; 96:5800982. [PMID: 32149339 DOI: 10.1093/femsec/fiaa038] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2019] [Accepted: 03/05/2020] [Indexed: 01/24/2023] Open
Abstract
Interactions between plants and microbes are involved in biodiversity maintenance, community stability and ecosystem functioning. However, differences in the community and network structures between phyllosphere epiphytic and endophytic bacteria have rarely been investigated. Here, we examined phyllosphere epiphytic and endophytic bacterial communities of six mangrove species using Illumina MiSeq sequencing of the 16S rRNA gene. The results revealed that the community structure of epiphytic and endophytic bacteria was different. Plant identity significantly affected the diversity and community structure of both epiphytic and endophytic bacteria, with a greater effect on the community structure of the former than the latter. Network analysis showed that both plant-epiphytic and plant-endophytic bacterial network structures were characterized by significantly highly specialized and modular but lowly connected and anti-nested properties. Furthermore, the epiphytic bacterial network was more highly specialized and modular but less connected and more strongly anti-nested than the endophytic bacterial network. This study reveals that the phyllosphere epiphytic and endophytic bacterial community structures differ and plant identity has a greater effect on the epiphytic than on the endophytic bacteria, which may provide a comprehensive insight into the role of plant identity in driving the phyllosphere epiphytic and endophytic microbial community structures in mangrove ecosystems.
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Affiliation(s)
- Hui Yao
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xiang Sun
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Chao He
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100193, China
| | - Xing-Chun Li
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Liang-Dong Guo
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
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Wilhelm RC, Murphy SJL, Feriancek NM, Karasz DC, DeRito CM, Newman JD, Buckley DH. Paraburkholderia madseniana sp. nov., a phenolic acid-degrading bacterium isolated from acidic forest soil. Int J Syst Evol Microbiol 2020; 70:2137-2146. [PMID: 32027304 DOI: 10.1099/ijsem.0.004029] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
RP11T was isolated from forest soil following enrichment with 4-hydroxybenzoic acid. Cells of RP11T are aerobic, non-sporulating, exhibit swimming motility, and are rods (0.8 µm by 1.4 µm) that often occur as diplobacillus or in short chains (3-4 cells). Optimal growth on minimal media containing 4-hydroxybenzoic acid (µ=0.216 hr-1) occurred at 30 °C, pH 6.5 or 7.0 and 0% salinity. Comparative chemotaxonomic, genomic and phylogenetic analyses revealed the isolate was distinct from its closest relative type strains identified as Paraburkholderia aspalathi LMG 27731T, Paraburkholderia fungorum LMG 16225T and Paraburkholderia caffeinilytica CF1T. Strain RP11T is genetically distinct from P. aspalathi, its closest relative, in terms of 16S rRNA gene sequence similarity (98.7%), genomic average nucleotide identity (94%) and in silico DNA-DNA hybridization (56.7 %±2.8). The composition of fatty acids and substrate utilization pattern differentiated strain RP11T from its closest relatives, including growth on phthalic acid. Strain RP11T encoded the greatest number of aromatic degradation genes of all eleven closely related type strains and uniquely encoded a phthalic acid dioxygenase and paralog of the 3-hydroxybenzoate 4-monooxygenase. The only ubiquinone detected in strain RP11T was Q-8, and the major cellular fatty acids were C16 : 0, 3OH-C16 : 0, C17 : 0 cyclo, C19 : 0 cyclo ω8c, and summed feature 8 (C18 : 1 ω7c/ω6c). On the basis of this polyphasic approach, it was determined that strain RP11T represents a novel species from the genus Paraburkholderia for which the name Paraburkholderia madseniana sp. nov. is proposed. The type strain is RP11T (=DSM 110123T=LMG 31517T).
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Affiliation(s)
- Roland C Wilhelm
- School of Integrative Plant Sciences, Bradfield Hall, Cornell University, Ithaca, NY, 14853, USA
| | - Sean J L Murphy
- School of Integrative Plant Sciences, Bradfield Hall, Cornell University, Ithaca, NY, 14853, USA
| | - Nicole M Feriancek
- School of Integrative Plant Sciences, Bradfield Hall, Cornell University, Ithaca, NY, 14853, USA
| | - David C Karasz
- School of Integrative Plant Sciences, Bradfield Hall, Cornell University, Ithaca, NY, 14853, USA
| | - Christopher M DeRito
- Department of Microbiology, Wing Hall, Cornell University, Ithaca, NY, 14853, USA
| | | | - Daniel H Buckley
- School of Integrative Plant Sciences, Bradfield Hall, Cornell University, Ithaca, NY, 14853, USA
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Wandrag EM, Birnbaum C, Klock MM, Barrett LG, Thrall PH. Availability of soil mutualists may not limit non‐native
Acacia
invasion but could increase their impact on native soil communities. J Appl Ecol 2020. [DOI: 10.1111/1365-2664.13577] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Elizabeth M. Wandrag
- School of Environmental and Rural Science University of New England Armidale NSW Australia
- Institute for Applied Ecology University of Canberra Canberra ACT Australia
| | | | - Metha M. Klock
- Department of Environmental Studies San José State University San José CA USA
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Komatsu KJ, Simms EL. Invasive legume management strategies differentially impact mutualist abundance and benefit to native and invasive hosts. Restor Ecol 2019. [DOI: 10.1111/rec.13081] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Kimberly J. Komatsu
- Smithsonian Environmental Research Center Edgewater MD 21037 U.S.A
- Department of Integrative Biology University of California Berkeley CA 94704 U.S.A
| | - Ellen L. Simms
- Department of Integrative Biology University of California Berkeley CA 94704 U.S.A
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Ramoneda J, Le Roux J, Frossard E, Bester C, Oettlé N, Frey B, Gamper HA. Insights from invasion ecology: Can consideration of eco-evolutionary experience promote benefits from root mutualisms in plant production? AOB PLANTS 2019; 11:plz060. [PMID: 31777649 PMCID: PMC6863469 DOI: 10.1093/aobpla/plz060] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Accepted: 09/13/2019] [Indexed: 06/10/2023]
Abstract
Mutualistic plant-microbial functioning relies on co-adapted symbiotic partners as well as conducive environmental conditions. Choosing particular plant genotypes for domestication and subsequent cultivar selection can narrow the gene pools of crop plants to a degree that they are no longer able to benefit from microbial mutualists. Elevated mineral nutrient levels in cultivated soils also reduce the dependence of crops on nutritional support by mutualists such as mycorrhizal fungi and rhizobia. Thus, current ways of crop production are predestined to compromise the propagation and function of microbial symbionts, limiting their long-term benefits for plant yield stability. The influence of mutualists on non-native plant establishment and spread, i.e. biological invasions, provides an unexplored analogue to contemporary crop production that accounts for mutualistic services from symbionts like rhizobia and mycorrhizae. The historical exposure of organisms to biotic interactions over evolutionary timescales, or so-called eco-evolutionary experience (EEE), has been used to explain the success of such invasions. In this paper, we stress that consideration of the EEE concept can shed light on how to overcome the loss of microbial mutualist functions following crop domestication and breeding. We propose specific experimental approaches to utilize the wild ancestors of crops to determine whether crop domestication compromised the benefits derived from root microbial symbioses or not. This can predict the potential for success of mutualistic symbiosis manipulation in modern crops and the maintenance of effective microbial mutualisms over the long term.
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Affiliation(s)
- Josep Ramoneda
- Group of Plant Nutrition, Department of Environmental Systems Science, ETH Zurich, Lindau, Switzerland
| | - Johannes Le Roux
- Department of Biological Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Emmanuel Frossard
- Group of Plant Nutrition, Department of Environmental Systems Science, ETH Zurich, Lindau, Switzerland
| | - Cecilia Bester
- South African Agricultural Research Council (ARC-Infruitec), Nieuwoudtville Northern Cape, Stellenbosch Central, Stellenbosch, South Africa
| | - Noel Oettlé
- Environmental Monitoring Group (EMG), Nieuwoudtville Northern Cape, South Africa
| | - Beat Frey
- Rhizosphere Processes Group, Swiss Federal Research Institute WSL, Birmensdorf, Switzerland
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Monteiro PHR, Kaschuk G, Winagraski E, Auer CG, Higa AR. Rhizobial inoculation in black wattle plantation (Acacia mearnsii De Wild.) in production systems of southern Brazil. Braz J Microbiol 2019; 50:989-998. [PMID: 31463869 PMCID: PMC6863320 DOI: 10.1007/s42770-019-00148-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 08/22/2019] [Indexed: 11/30/2022] Open
Abstract
Black wattle (Acacia mearnsii De Wild.) is a tree legume native to southeast Australia, but present in all continents. Today it covers about 142,400 ha in Brazil, with plantations concentrated in the southern region of the country. Black wattle may form nodules and establish rhizobial symbiosis capable of fixing N2, but rhizobial inoculation is not done in commercial plantations. About 40 kg ha-1 of urea is applied during seedling transplantation. In this review, evidences by which rhizobial inoculation affects monoculture, mixed cultivation, and agroforestry black wattle production systems were searched in literature. Previous measurements in cultivated forests have indicated that biological nitrogen fixation in black wattle may provide up to 200 kg of N ha-1 year-1 to the soil. Therefore, rhizobia inoculation may bring several opportunities to improve black wattle production systems. Black wattle is not a very selective partner in the rhizobial symbiosis, but the genus Bradyrhizobium dominates the rhizobial diversity of black wattle nodules. Investigation on rhizobial diversity in soils where the crop is cultivated may represent an opportunity to find more effective rhizobia strains for inoculants. The successful history of biological nitrogen fixation in grain legumes must inspire the history of tree legumes. Microbiology applied to forestry must overcome challenges on the lack of trained professionals and the development of new application technologies.
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Affiliation(s)
- Pedro Henrique Riboldi Monteiro
- Departamento de Engenharia Florestal, Universidade Federal do Paraná, Av. Prefeito Lothário Meissner, 632, Jardim Botânico, Curitiba, Paraná 80210-170 Brazil
| | - Glaciela Kaschuk
- Departamento de Solos e Engenharia Agrícola, Universidade Federal do Paraná, Rua dos Funcionários, 1540, Curitiba, Paraná 80035-050 Brazil
| | - Etienne Winagraski
- Departamento de Engenharia Florestal, Universidade Federal do Paraná, Av. Prefeito Lothário Meissner, 632, Jardim Botânico, Curitiba, Paraná 80210-170 Brazil
| | - Celso Garcia Auer
- Departamento de Engenharia Florestal, Universidade Federal do Paraná, Av. Prefeito Lothário Meissner, 632, Jardim Botânico, Curitiba, Paraná 80210-170 Brazil
- Embrapa Florestas, Cx. Postal 319, Colombo, Paraná 83411-000 Brazil
| | - Antônio Rioyei Higa
- Departamento de Engenharia Florestal, Universidade Federal do Paraná, Av. Prefeito Lothário Meissner, 632, Jardim Botânico, Curitiba, Paraná 80210-170 Brazil
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Kamutando CN, Vikram S, Kamgan-Nkuekam G, Makhalanyane TP, Greve M, Le Roux JJ, Richardson DM, Cowan DA, Valverde A. The Functional Potential of the Rhizospheric Microbiome of an Invasive Tree Species, Acacia dealbata. MICROBIAL ECOLOGY 2019; 77:191-200. [PMID: 29948018 DOI: 10.1007/s00248-018-1214-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2018] [Accepted: 05/28/2018] [Indexed: 05/09/2023]
Abstract
Plant-microbe interactions mediate both the invasiveness of introduced plant species and the impacts that they have in invaded ecosystems. Although the phylogenetic composition of the rhizospheric microbiome of Acacia dealbata (an invasive Australian tree species) has been investigated, little is known about the functional potential of the constituents of these altered microbial communities. We used shotgun DNA sequencing to better understand the link between bacterial community composition and functional capacity in the rhizospheric microbiomes associated with invasive A. dealbata populations in South Africa. Our analysis showed that several genes associated with plant growth-promoting (PGP) traits were significantly overrepresented in the rhizospheric metagenomes compared to neighbouring bulk soils collected away from A. dealbata stands. The majority of these genes are involved in the metabolism of nitrogen, carbohydrates and vitamins, and in various membrane transport systems. Overrepresented genes were linked to a limited number of bacterial taxa, mostly Bradyrhizobium species, the preferred N-fixing rhizobial symbiont of Australian acacias. Overall, these findings suggest that A. dealbata enriches rhizosphere soils with potentially beneficial microbial taxa, and that members of the genus Bradyrhizobium may play an integral role in mediating PGP processes that may influence the success of this invader when colonizing novel environments.
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Affiliation(s)
- Casper N Kamutando
- Centre for Microbial Ecology and Genomics, Department of Genetics, University of Pretoria, Pretoria, South Africa
| | - Surendra Vikram
- Centre for Microbial Ecology and Genomics, Department of Genetics, University of Pretoria, Pretoria, South Africa
| | - Gilbert Kamgan-Nkuekam
- Centre for Microbial Ecology and Genomics, Department of Genetics, University of Pretoria, Pretoria, South Africa
| | - Thulani P Makhalanyane
- Centre for Microbial Ecology and Genomics, Department of Genetics, University of Pretoria, Pretoria, South Africa
| | - Michelle Greve
- Department of Plant and Soil Sciences, University of Pretoria, Pretoria, South Africa
| | - Johannes J Le Roux
- Centre for Invasion Biology, Department of Botany & Zoology, Stellenbosch University, Stellenbosch, South Africa
| | - David M Richardson
- Centre for Invasion Biology, Department of Botany & Zoology, Stellenbosch University, Stellenbosch, South Africa
| | - Don A Cowan
- Centre for Microbial Ecology and Genomics, Department of Genetics, University of Pretoria, Pretoria, South Africa
| | - Angel Valverde
- Centre for Microbial Ecology and Genomics, Department of Genetics, University of Pretoria, Pretoria, South Africa.
- Department of Microbial, Biochemical and Food Biotechnology, University of the Free State, P.O. Box 339, Bloemfontein, Free State, 9300, South Africa.
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13
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Jacobsen RM, Sverdrup-Thygeson A, Kauserud H, Birkemoe T. Revealing hidden insect-fungus interactions; moderately specialized, modular and anti-nested detritivore networks. Proc Biol Sci 2018; 285:rspb.2017.2833. [PMID: 29618548 DOI: 10.1098/rspb.2017.2833] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Accepted: 03/12/2018] [Indexed: 12/22/2022] Open
Abstract
Ecological networks are composed of interacting communities that influence ecosystem structure and function. Fungi are the driving force for ecosystem processes such as decomposition and carbon sequestration in terrestrial habitats, and are strongly influenced by interactions with invertebrates. Yet, interactions in detritivore communities have rarely been considered from a network perspective. In the present study, we analyse the interaction networks between three functional guilds of fungi and insects sampled from dead wood. Using DNA metabarcoding to identify fungi, we reveal a diversity of interactions differing in specificity in the detritivore networks, involving three guilds of fungi. Plant pathogenic fungi were relatively unspecialized in their interactions with insects inhabiting dead wood, while interactions between the insects and wood-decay fungi exhibited the highest degree of specialization, which was similar to estimates for animal-mediated seed dispersal networks in previous studies. The low degree of specialization for insect symbiont fungi was unexpected. In general, the pooled insect-fungus networks were significantly more specialized, more modular and less nested than randomized networks. Thus, the detritivore networks had an unusual anti-nested structure. Future studies might corroborate whether this is a common aspect of networks based on interactions with fungi, possibly owing to their often intense competition for substrate.
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Affiliation(s)
- Rannveig M Jacobsen
- Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, Høgskoleveien 12, 1433 Ås, Norway .,The Norwegian Institute for Nature Research (NINA), Gaustadalléen 21, 0349 Oslo, Norway
| | - Anne Sverdrup-Thygeson
- Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, Høgskoleveien 12, 1433 Ås, Norway
| | - Håvard Kauserud
- Section for Genetics and Evolutionary Biology (EVOGENE), University of Oslo, Blindernveien 31, 0316 Oslo, Norway
| | - Tone Birkemoe
- Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, Høgskoleveien 12, 1433 Ås, Norway
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Le Roux JJ, Hui C, Keet JH, Ellis AG. Co-introduction vs ecological fitting as pathways to the establishment of effective mutualisms during biological invasions. THE NEW PHYTOLOGIST 2017; 215:1354-1360. [PMID: 28771816 DOI: 10.1111/nph.14593] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Accepted: 03/24/2017] [Indexed: 06/07/2023]
Abstract
Contents 1354 I. 1354 II. 1355 III. 1357 IV. 1357 V. 1359 1359 References 1359 SUMMARY: Interactions between non-native plants and their mutualists are often disrupted upon introduction to new environments. Using legume-rhizobium mutualistic interactions as an example, we discuss two pathways that can influence symbiotic associations in such situations: co-introduction of coevolved rhizobia; and utilization of, and adaptation to, resident rhizobia, hereafter referred to as 'ecological fitting'. Co-introduction and ecological fitting have distinct implications for successful legume invasions and their impacts. Under ecological fitting, initial impacts may be less severe and will accrue over longer periods as novel symbiotic associations and/or adaptations may require fine-tuning over time. Co-introduction will have more profound impacts that will accrue more rapidly as a result of positive feedbacks between densities of non-native rhizobia and their coevolved host plants, in turn enhancing competition between native and non-native rhizobia. Co-introduction can further impact invasion outcomes by the exchange of genetic material between native and non-native rhizobia, potentially resulting in decreased fitness of native legumes. A better understanding of the roles of these two pathways in the invasion dynamics of non-native legumes is much needed, and we highlight some of the exciting research avenues it presents.
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Affiliation(s)
- Johannes J Le Roux
- Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Matieland, 7602, South Africa
- Department of Botany and Zoology, Stellenbosch University, Matieland, 7602, South Africa
| | - Cang Hui
- Centre for Invasion Biology, Department of Mathematical Sciences, Stellenbosch University, Matieland, 7602, South Africa
- Mathematical and Physical Biosciences, African Institute for Mathematical Sciences, Cape Town, 7945, South Africa
| | - Jan-Hendrik Keet
- Department of Botany and Zoology, Stellenbosch University, Matieland, 7602, South Africa
| | - Allan G Ellis
- Department of Botany and Zoology, Stellenbosch University, Matieland, 7602, South Africa
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Kamutando CN, Vikram S, Kamgan-Nkuekam G, Makhalanyane TP, Greve M, Roux JJL, Richardson DM, Cowan D, Valverde A. Soil nutritional status and biogeography influence rhizosphere microbial communities associated with the invasive tree Acacia dealbata. Sci Rep 2017; 7:6472. [PMID: 28747705 PMCID: PMC5529528 DOI: 10.1038/s41598-017-07018-w] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Accepted: 06/20/2017] [Indexed: 01/08/2023] Open
Abstract
Invasiveness and the impacts of introduced plants are known to be mediated by plant-microbe interactions. Yet, the microbial communities associated with invasive plants are generally poorly understood. Here we report on the first comprehensive investigation of the bacterial and fungal communities inhabiting the rhizosphere and the surrounding bulk soil of a widespread invasive tree, Acacia dealbata. Amplicon sequencing data indicated that rhizospheric microbial communities differed significantly in structure and composition from those of the bulk soil. Two bacterial (Alphaproteobacteria and Gammaproteobacteria) and two fungal (Pezizomycetes and Agaricomycetes) classes were enriched in the rhizosphere compared with bulk soils. Changes in nutritional status, possibly induced by A. dealbata, primarily shaped rhizosphere soil communities. Despite a high degree of geographic variability in the diversity and composition of microbial communities, invasive A. dealbata populations shared a core of bacterial and fungal taxa, some of which are known to be involved in N and P cycling, while others are regarded as plant pathogens. Shotgun metagenomic analysis also showed that several functional genes related to plant growth promotion were overrepresented in the rhizospheres of A. dealbata. Overall, results suggest that rhizosphere microbes may contribute to the widespread success of this invader in novel environments.
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Affiliation(s)
- Casper N Kamutando
- Centre for Microbial Ecology and Genomics, Department of Genetics, University of Pretoria, Pretoria, South Africa
| | - Surendra Vikram
- Centre for Microbial Ecology and Genomics, Department of Genetics, University of Pretoria, Pretoria, South Africa
| | - Gilbert Kamgan-Nkuekam
- Centre for Microbial Ecology and Genomics, Department of Genetics, University of Pretoria, Pretoria, South Africa
| | - Thulani P Makhalanyane
- Centre for Microbial Ecology and Genomics, Department of Genetics, University of Pretoria, Pretoria, South Africa
| | - Michelle Greve
- Department of Plant and Soil Sciences, University of Pretoria, Pretoria, South Africa
| | - Johannes J Le Roux
- Centre for Invasion Biology, Department of Botany & Zoology, Stellenbosch University, Stellenbosch, South Africa
| | - David M Richardson
- Centre for Invasion Biology, Department of Botany & Zoology, Stellenbosch University, Stellenbosch, South Africa
| | - Don Cowan
- Centre for Microbial Ecology and Genomics, Department of Genetics, University of Pretoria, Pretoria, South Africa
| | - Angel Valverde
- Centre for Microbial Ecology and Genomics, Department of Genetics, University of Pretoria, Pretoria, South Africa.
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Keet JH, Ellis AG, Hui C, Le Roux JJ. Legume-rhizobium symbiotic promiscuity and effectiveness do not affect plant invasiveness. ANNALS OF BOTANY 2017; 119:1319-1331. [PMID: 28369229 PMCID: PMC5604570 DOI: 10.1093/aob/mcx028] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2016] [Accepted: 02/22/2017] [Indexed: 06/07/2023]
Abstract
BACKGROUND AND AIMS The ability to fix atmospheric nitrogen is thought to play an important role in the invasion success of legumes. Interactions between legumes and nitrogen-fixing bacteria (rhizobia) span a continuum of specialization, and promiscuous legumes are thought to have higher chances of forming effective symbioses in novel ranges. Using Australian Acacia species in South Africa, it was hypothesized that widespread and highly invasive species will be more generalist in their rhizobial symbiotic requirements and more effective in fixing atmospheric nitrogen compared with localized and less invasive species. METHODS To test these hypotheses, eight localized and 11 widespread acacias were examined using next-generation sequencing data for the nodulation gene, nodC , to compare the identity, species richness, diversity and compositional similarity of rhizobia associated with these acacias. Stable isotope analysis was also used to determine levels of nitrogen obtained from the atmosphere via symbiotic nitrogen fixation. KEY RESULTS No differences were found in richness, diversity and community composition between localized and widespread acacias. Similarly, widespread and localized acacias did not differ in their ability to fix atmospheric nitrogen. However, for some species by site comparisons, significant differences in δ15N isotopic signatures were found, indicating differential symbiotic effectiveness between these species at specific localities. CONCLUSIONS Overall, the results support recent findings that root nodule rhizobial diversity and community composition do not differ between acacias that vary in their invasiveness. Differential invasiveness of acacias in South Africa is probably linked to attributes such as differences in propagule pressure, reasons for (e.g. forestry vs. ornamental) and extent of, plantings in the country.
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Affiliation(s)
- Jan-Hendrik Keet
- Department of Botany and Zoology, Stellenbosch University, Matieland 7602, South Africa
| | - Allan G. Ellis
- Department of Botany and Zoology, Stellenbosch University, Matieland 7602, South Africa
| | - Cang Hui
- Centre for Invasion Biology, Department of Mathematical Sciences, Stellenbosch University, Matieland 7602, South Africa
- Mathematical and Physical Biosciences, African Institute for Mathematical Sciences, Cape Town 7945, South Africa
| | - Johannes J. Le Roux
- Department of Botany and Zoology, Stellenbosch University, Matieland 7602, South Africa
- Centre for Invasion Biology, Department of Mathematical Sciences, Stellenbosch University, Matieland 7602, South Africa
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17
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Hirsch H, Richardson DM, Le Roux JJ. Introduction to the special issue: Tree invasions: towards a better understanding of their complex evolutionary dynamics. AOB PLANTS 2017; 9:plx014. [PMID: 28533897 PMCID: PMC5420828 DOI: 10.1093/aobpla/plx014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Accepted: 04/03/2017] [Indexed: 06/07/2023]
Abstract
Many invasive plants show evidence of trait-based evolutionary change, but these remain largely unexplored for invasive trees. The increasing number of invasive trees and their tremendous impacts worldwide, however, illustrates the urgent need to bridge this knowledge gap to apply efficient management. Consequently, an interdisciplinary workshop, held in 2015 at Stellenbosch University in Stellenbosch, South Africa, brought together international researchers to discuss our understanding of evolutionary dynamics in invasive trees. The main outcome of this workshop is this Special Issue of AoB PLANTS. The collection of papers in this issue has helped to identify and assess the evolutionary mechanisms that are likely to influence tree invasions. It also facilitated expansion of the unified framework for biological invasions to incorporate key evolutionary processes. The papers cover a wide range of evolutionary mechanisms in tree genomes (adaptation), epigenomes (phenotypic plasticity) and their second genomes (mutualists), and show how such mechanisms can impact tree invasion processes and management. The special issue provides a comprehensive overview of the factors that promote and mitigate the invasive success of tree species in many parts of the world. It also shows that incorporating evolutionary concepts is crucial for understanding the complex drivers of tree invasions and has much potential to improve management. The contributions of the special issue also highlight many priorities for further work in the face of ever-increasing tree invasions; the complexity of this research needs calls for expanded interdisciplinary research collaborations.
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Affiliation(s)
- Heidi Hirsch
- Centre for Invasion Biology, Department of Botany & Zoology, Stellenbosch University, Matieland 7602, South Africa
| | - David M. Richardson
- Centre for Invasion Biology, Department of Botany & Zoology, Stellenbosch University, Matieland 7602, South Africa
| | - Johannes J. Le Roux
- Centre for Invasion Biology, Department of Botany & Zoology, Stellenbosch University, Matieland 7602, South Africa
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Burgess TI, Crous CJ, Slippers B, Hantula J, Wingfield MJ. Tree invasions and biosecurity: eco-evolutionary dynamics of hitchhiking fungi. AOB PLANTS 2017; 8:plw076. [PMID: 27821517 PMCID: PMC5206332 DOI: 10.1093/aobpla/plw076] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Accepted: 10/26/2016] [Indexed: 05/28/2023]
Abstract
When non-native plants reach novel environments, they typically arrive with hidden microbiomes. In general, most of these hitchhikers remain on their co-evolved hosts, some contribute to the invasiveness of their hosts, and a small number can undergo host shifts and move onto native hosts. Invasion success can vary depending upon the different categories of fungal associates. When an invader tree relies on a fungal mutualism to survive in the new environment, there is a fundamentally lower likelihood of either the tree, or the fungus, establishing novel associations. In contrast, parasitic hitchhikers could merely use their host plants to move through the landscape and to become established on new hosts (host shifts). Evidence suggests the frequency of these host shifts is low and depends upon the fungal functional group. However, epidemics caused by invasive pathogens in native ecosystems have occurred globally. Thus, elucidating the potential for hidden non-native fungi to form novel host associations in a new environment is important for biodiversity conservation.
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Affiliation(s)
- Treena I Burgess
- Centre of Phytophthora Science and Management, School of Veterinary and Life Science, Murdoch University, Murdoch 6150, Australia
- Forestry and Agricultural Biotechnology Institute, University of Pretoria, Pretoria 0002, South Africa
| | - Casparus J Crous
- Forestry and Agricultural Biotechnology Institute, University of Pretoria, Pretoria 0002, South Africa
- Present address: Centre for Ecology, Evolution and Environmental Changes, Faculty of Sciences, University of Lisbon, Campo Grande, Lisbon 1749-016, Portugal
| | - Bernard Slippers
- Forestry and Agricultural Biotechnology Institute, University of Pretoria, Pretoria 0002, South Africa
| | - Jarkko Hantula
- Natural Resources Institute Finland, Natural Resources and Bioproduction Unit, Vantaa 01300, Finland
| | - Michael J Wingfield
- Centre of Phytophthora Science and Management, School of Veterinary and Life Science, Murdoch University, Murdoch 6150, Australia
- Forestry and Agricultural Biotechnology Institute, University of Pretoria, Pretoria 0002, South Africa
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Zenni RD, Dickie IA, Wingfield MJ, Hirsch H, Crous CJ, Meyerson LA, Burgess TI, Zimmermann TG, Klock MM, Siemann E, Erfmeier A, Aragon R, Montti L, Le Roux JJ. Evolutionary dynamics of tree invasions: complementing the unified framework for biological invasions. AOB PLANTS 2016; 9:plw085. [PMID: 28039118 PMCID: PMC5391705 DOI: 10.1093/aobpla/plw085] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Revised: 08/09/2016] [Accepted: 11/16/2016] [Indexed: 05/24/2023]
Abstract
Evolutionary processes greatly impact the outcomes of biological invasions. An extensive body of research suggests that invasive populations often undergo phenotypic and ecological divergence from their native sources. Evolution also operates at different and distinct stages during the invasion process. Thus, it is important to incorporate evolutionary change into frameworks of biological invasions because it allows us to conceptualize how these processes may facilitate or hinder invasion success. Here, we review such processes, with an emphasis on tree invasions, and place them in the context of the unified framework for biological invasions. The processes and mechanisms described are pre-introduction evolutionary history, sampling effect, founder effect, genotype-by-environment interactions, admixture, hybridization, polyploidization, rapid evolution, epigenetics, and second-genomes. For the last, we propose that co-evolved symbionts, both beneficial and harmful, which are closely physiologically associated with invasive species, contain critical genetic traits that affect the evolutionary dynamics of biological invasions. By understanding the mechanisms underlying invasion success, researchers will be better equipped to predict, understand, and manage biological invasions.
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Affiliation(s)
- Rafael Dudeque Zenni
- Setor de Ecologia, Departamento de Biologia, Universidade Federal de Lavras, Lavras, MG, Brazil. Programa de Pós-Graduação em Ecologia Aplicada, Caixa Postal 3037, CEP 37200-000 - Lavras-MG - Brazil
| | - Ian A Dickie
- Bio-protection Research Centre, Lincoln University, Lincoln 7647, New Zealand
| | - Michael J Wingfield
- Forestry & Agricultural Biotechnology Institute, University of Pretoria, Pretoria, South Africa
| | - Heidi Hirsch
- Centre for Invasion Biology, Department of Botany & Zoology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa
| | - Casparus J Crous
- Forestry & Agricultural Biotechnology Institute, University of Pretoria, Pretoria, South Africa
- Centre for Ecology, Evolution and Environmental Changes, Faculty of Sciences, University of Lisbon, Campo Grande, 1749-016, Lisbon, Portugal
| | - Laura A Meyerson
- Department of Natural Resources Science, University of Rhode Island, Kingston, RI, USA
| | - Treena I Burgess
- Forestry & Agricultural Biotechnology Institute, University of Pretoria, Pretoria, South Africa
- School of Veterinary and Life Sciences, Murdoch University, Murdoch, 6150 Australia
| | - Thalita G Zimmermann
- Instituto de Pesquisas Jardim Botânico do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Metha M Klock
- Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, USA
| | - Evan Siemann
- Biosciences Department, Rice University, Houston, TX, USA
| | | | - Roxana Aragon
- Instituto de Ecologia Regional, Facultad de Ciencias Naturales, Universidad Nacional de Tucumán, CONICET. Tucuman, Argentina
| | - Lia Montti
- Instituto de Ecologia Regional, Facultad de Ciencias Naturales, Universidad Nacional de Tucumán, CONICET. Tucuman, Argentina
| | - Johannes J Le Roux
- Centre for Invasion Biology, Department of Botany & Zoology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa
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20
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Dickie IA, Cooper JA, Bufford JL, Hulme PE, Bates ST. Loss of functional diversity and network modularity in introduced plant-fungal symbioses. AOB PLANTS 2016; 9:plw084. [PMID: 28039116 PMCID: PMC5391694 DOI: 10.1093/aobpla/plw084] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2016] [Revised: 10/09/2016] [Accepted: 10/26/2016] [Indexed: 05/31/2023]
Abstract
The introduction of alien plants into a new range can result in the loss of co-evolved symbiotic organisms, such as mycorrhizal fungi, that are essential for normal plant physiological functions. Prior studies of mycorrhizal associations in alien plants have tended to focus on individual plant species on a case-by-case basis. This approach limits broad scale understanding of functional shifts and changes in interaction network structure that may occur following introduction. Here we use two extensive datasets of plant-fungal interactions derived from fungal sporocarp observations and recorded plant hosts in two island archipelago nations: New Zealand (NZ) and the United Kingdom (UK). We found that the NZ dataset shows a lower functional diversity of fungal hyphal foraging strategies in mycorrhiza of alien as compared with native trees. Across species this resulted in fungal foraging strategies associated with alien trees being much more variable in functional composition compared with native trees, which had a strikingly similar functional composition. The UK data showed no functional difference in fungal associates of alien and native plant genera. Notwithstanding this, both the NZ and UK data showed a substantial difference in interaction network structure of alien trees compared with native trees. In both cases, fungal associates of native trees showed strong modularity, while fungal associates of alien trees generally integrated into a single large module. The results suggest a lower functional diversity (in one dataset) and a simplification of network structure (in both) as a result of introduction, potentially driven by either limited symbiont co-introductions or disruption of habitat as a driver of specificity due to nursery conditions, planting, or plant edaphic-niche expansion. Recognizing these shifts in function and network structure has important implications for plant invasions and facilitation of secondary invasions via shared mutualist populations.
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Affiliation(s)
- Ian A Dickie
- Bio-Protection Research Centre, Lincoln University, Box 85084, Lincoln 7647, New Zealand
| | - Jerry A Cooper
- Landcare Research, PO Box 69040, Lincoln 7640, New Zealand
| | - Jennifer L Bufford
- Bio-Protection Research Centre, Lincoln University, Box 85084, Lincoln 7647, New Zealand
| | - Philip E Hulme
- Bio-Protection Research Centre, Lincoln University, Box 85084, Lincoln 7647, New Zealand
| | - Scott T Bates
- Bio-Protection Research Centre, Lincoln University, Box 85084, Lincoln 7647, New Zealand
- Landcare Research, PO Box 69040, Lincoln 7640, New Zealand
- Department of Plant Pathology, University of Minnesota, Saint Paul, MN 55108, United States of America
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Crous CJ, Burgess TI, Le Roux JJ, Richardson DM, Slippers B, Wingfield MJ. Ecological disequilibrium drives insect pest and pathogen accumulation in non-native trees. AOB PLANTS 2016; 9:plw081. [PMID: 28013250 PMCID: PMC5499825 DOI: 10.1093/aobpla/plw081] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Revised: 08/08/2016] [Accepted: 11/10/2016] [Indexed: 05/16/2023]
Abstract
Non-native trees have become dominant components of many landscapes, including urban ecosystems, commercial forestry plantations, fruit orchards, and as invasives in natural ecosystems. Often, these trees have been separated from their natural enemies (i.e. insects and pathogens) leading to ecological disequilibrium, that is, the immediate breakdown of historically co-evolved interactions once introduced into novel environments. Long-established, non-native tree plantations provide useful experiments to explore the dimensions of such ecological disequilibria. We quantify the status quo of non-native insect pests and pathogens catching up with their tree hosts (planted Acacia, Eucalyptus and Pinus species) in South Africa, and examine which native South African enemy species utilise these trees as hosts. Interestingly, pines, with no confamilial relatives in South Africa and the longest residence time (almost two centuries), have acquired only one highly polyphagous native pathogen. This is in contrast to acacias and eucalypts, both with many native and confamilial relatives in South Africa that have acquired more native pathogens. These patterns support the known role of phylogenetic relatedness of non-native and native floras in influencing the likelihood of pathogen shifts between them. This relationship, however, does not seem to hold for native insects. Native insects appear far more likely to expand their feeding habits onto non-native tree hosts than are native pathogens, although they are generally less damaging. The ecological disequilibrium conditions of non-native trees are deeply rooted in the eco-evolutionary experience of the host plant, co-evolved natural enemies, and native organisms from the introduced range. We should expect considerable spatial and temporal variation in ecological disequilibrium conditions among non-native taxa, which can be significantly influenced by biosecurity and management practices.
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Affiliation(s)
- Casparus J Crous
- Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria, 0002, South Africa
- Present address: Centre for Ecology, Evolution and Environmental Changes, Faculty of Sciences, University of Lisbon, Campo Grande, 1749-016, Lisbon, Portugal
| | - Treena I Burgess
- Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria, 0002, South Africa
- Centre for Phytophthora Science and Management, School of Veterinary and Life Sciences, Murdoch University, 90 South Street, Murdoch, WA 6150, Australia
| | - Johannes J Le Roux
- Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa
| | - David M Richardson
- Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa
| | - Bernard Slippers
- Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria, 0002, South Africa
| | - Michael J Wingfield
- Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria, 0002, South Africa
- Centre for Phytophthora Science and Management, School of Veterinary and Life Sciences, Murdoch University, 90 South Street, Murdoch, WA 6150, Australia
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Besnard G, Cuneo P. An ecological and evolutionary perspective on the parallel invasion of two cross-compatible trees. AOB PLANTS 2016; 8:plw056. [PMID: 27519914 PMCID: PMC5018386 DOI: 10.1093/aobpla/plw056] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 08/01/2016] [Indexed: 05/29/2023]
Abstract
Invasive trees are generally seen as ecosystem-transforming plants that can have significant impacts on native vegetation, and often require management and control. Understanding their history and biology is essential to guide actions of land managers. Here, we present a summary of recent research into the ecology, phylogeography and management of invasive olives, which are now established outside of their native range as high ecological impact invasive trees. The parallel invasion of European and African olive in different climatic zones of Australia provides an interesting case study of invasion, characterized by early genetic admixture between domesticated and wild taxa. Today, the impact of the invasive olives on native vegetation and ecosystem function is of conservation concern, with European olive a declared weed in areas of South Australia, and African olive a declared weed in New South Wales and Pacific islands. Population genetics was used to trace the origins and invasion of both subspecies in Australia, indicating that both olive subspecies have hybridized early after introduction. Research also indicates that African olive populations can establish from a low number of founder individuals even after successive bottlenecks. Modelling based on distributional data from the native and invasive range identified a shift of the realized ecological niche in the Australian invasive range for both olive subspecies, which was particularly marked for African olive. As highly successful and long-lived invaders, olives offer further opportunities to understand the genetic basis of invasion, and we propose that future research examines the history of introduction and admixture, the genetic basis of adaptability and the role of biotic interactions during invasion. Advances on these questions will ultimately improve predictions on the future olive expansion and provide a solid basis for better management of invasive populations.
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Affiliation(s)
- Guillaume Besnard
- CNRS, UPS, ENFA, Laboratoire Evolution & Diversité Biologique, UMR 5174, 31062 Toulouse 4, France
| | - Peter Cuneo
- The Australian PlantBank, Royal Botanic Gardens and Domain Trust, The Australian Botanic Garden, Mount Annan, NSW 2567, Australia
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