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Rose BD, Dellinger MA, Larmour CP, Polishook MI, Higuita-Aguirre MI, Dutta S, Cook RL, Zimmermann SD, Garcia K. The ectomycorrhizal fungus Paxillus ammoniavirescens influences the effects of salinity on loblolly pine in response to potassium availability. Environ Microbiol 2024; 26:e16597. [PMID: 38450872 DOI: 10.1111/1462-2920.16597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Accepted: 02/09/2024] [Indexed: 03/08/2024]
Abstract
Salinity is an increasing problem in coastal areas affected by saltwater intrusion, with deleterious effects on tree health and forest growth. Ectomycorrhizal (ECM) fungi may improve the salinity tolerance of host trees, but the impact of external potassium (K+ ) availability on these effects is still unclear. Here, we performed several experiments with the ECM fungus Paxillus ammoniavirescens and loblolly pine (Pinus taeda L.) in axenic and symbiotic conditions at limited or sufficient K+ and increasing sodium (Na+ ) concentrations. Growth rate, biomass, nutrient content, and K+ transporter expression levels were recorded for the fungus, and the colonization rate, root development parameters, biomass, and shoot nutrient accumulation were determined for mycorrhizal and non-mycorrhizal plants. P. ammoniavirescens was tolerant to high salinity, although growth and nutrient concentrations varied with K+ availability and increasing Na+ exposure. While loblolly pine root growth and development decreased with increasing salinity, ECM colonization was unaffected by pine response to salinity. The mycorrhizal influence on loblolly pine salinity response was strongly dependent on external K+ availability. This study reveals that P. ammoniavirescens can reduce Na+ accumulation of salt-exposed loblolly pine, but this effect depends on external K+ availability.
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Affiliation(s)
- Benjamin D Rose
- Department of Crop and Soil Sciences, North Carolina State University, Raleigh, North Carolina, USA
| | - Marissa A Dellinger
- Department of Crop and Soil Sciences, North Carolina State University, Raleigh, North Carolina, USA
| | - Clancy P Larmour
- Department of Crop and Soil Sciences, North Carolina State University, Raleigh, North Carolina, USA
| | - Mira I Polishook
- Department of Crop and Soil Sciences, North Carolina State University, Raleigh, North Carolina, USA
| | - Maria I Higuita-Aguirre
- Department of Crop and Soil Sciences, North Carolina State University, Raleigh, North Carolina, USA
- Department of Forestry and Environmental Resources, North Carolina State University, Raleigh, North Carolina, USA
| | - Summi Dutta
- Department of Crop and Soil Sciences, North Carolina State University, Raleigh, North Carolina, USA
| | - Rachel L Cook
- Department of Forestry and Environmental Resources, North Carolina State University, Raleigh, North Carolina, USA
| | - Sabine D Zimmermann
- IPSiM, University of Montpellier, CNRS, INRAE, Institut Agro, Montpellier, France
| | - Kevin Garcia
- Department of Crop and Soil Sciences, North Carolina State University, Raleigh, North Carolina, USA
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Dutta S, Houdinet G, NandaKafle G, Kafle A, Hawkes CV, Garcia K. Agrobacterium tumefaciens-mediated transformation of Nigrospora sp. isolated from switchgrass leaves and antagonistic toward plant pathogens. J Microbiol Methods 2023; 215:106849. [PMID: 37907117 DOI: 10.1016/j.mimet.2023.106849] [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: 08/11/2023] [Revised: 10/25/2023] [Accepted: 10/25/2023] [Indexed: 11/02/2023]
Abstract
Nigrospora is a diverse genus of fungi colonizing plants through endophytic, pathogenic, or saprobic interactions. Endophytic isolates can improve growth and development of host plants, as well as their resistance to microbial pathogens, but exactly how they do so remains poorly understood. Developing a reliable transformation method is crucial to investigate these mechanisms, in particular to identify pivotal genes for specific functions that correlate with specific traits. In this study, we identified eight isolates of Nigrospora sp. internally colonizing the leaves of switchgrass plants cultivated in North Carolina. Using an Agrobacterium tumefaciens-mediated transformation approach with control and GFP-expressing vectors, we report the first successful transformation of two Nigrospora isolates. Finally, we demonstrate that wild-type and transgenic isolates both negatively impact the growth of two plant pathogens in co-culture conditions, Bipolaris maydis and Parastagonospora nodorum, responsible for the Southern Leaf Blight and Septoria Nodorum Blotch diseases, respectively. The GFP-transformed strains developed here can therefore serve as accurate reporters of spatial interactions in future studies of Nigrospora and pathogens in the plant. Finally, the transformation method we describe lays the foundation for further genetic research on the Nigrospora genus to expand our mechanistic understanding of plant-endophyte interactions.
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Affiliation(s)
- Summi Dutta
- Department of Crop and Soil Sciences, North Carolina State University, Raleigh, NC 27695, USA; Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC 27695, USA
| | - Gabriella Houdinet
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27607, USA
| | - Gitanjali NandaKafle
- Department of Crop and Soil Sciences, North Carolina State University, Raleigh, NC 27695, USA
| | - Arjun Kafle
- Department of Crop and Soil Sciences, North Carolina State University, Raleigh, NC 27695, USA
| | - Christine V Hawkes
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27607, USA
| | - Kevin Garcia
- Department of Crop and Soil Sciences, North Carolina State University, Raleigh, NC 27695, USA.
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Secrets of the fungus-specific potassium channel TOK family. Trends Microbiol 2022; 31:511-520. [PMID: 36567187 DOI: 10.1016/j.tim.2022.11.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2022] [Revised: 11/16/2022] [Accepted: 11/18/2022] [Indexed: 12/25/2022]
Abstract
Several families of potassium (K+) channels are found in membranes of all eukaryotes, underlining the importance of K+ uptake and redistribution within and between cells and organs. Among them, TOK (tandem-pore outward-rectifying K+) channels consist of eight transmembrane domains and two pore domains per subunit organized in dimers. These channels were originally studied in yeast, but recent identifications and characterizations in filamentous fungi shed new light on this fungus-specific K+ channel family. Although their actual function in vivo is often puzzling, recent works indicate a role in cellular K+ homeostasis and even suggest a role in plant-fungus symbioses. This review aims at synthesizing the current knowledge on fungal TOK channels and discussing their potential role in yeasts and filamentous fungi.
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Branco S, Schauster A, Liao HL, Ruytinx J. Mechanisms of stress tolerance and their effects on the ecology and evolution of mycorrhizal fungi. THE NEW PHYTOLOGIST 2022; 235:2158-2175. [PMID: 35713988 DOI: 10.1111/nph.18308] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Accepted: 05/11/2022] [Indexed: 05/25/2023]
Abstract
Stress is ubiquitous and disrupts homeostasis, leading to damage, decreased fitness, and even death. Like other organisms, mycorrhizal fungi evolved mechanisms for stress tolerance that allow them to persist or even thrive under environmental stress. Such mechanisms can also protect their obligate plant partners, contributing to their health and survival under hostile conditions. Here we review the effects of stress and mechanisms of stress response in mycorrhizal fungi. We cover molecular and cellular aspects of stress and how stress impacts individual fitness, physiology, growth, reproduction, and interactions with plant partners, along with how some fungi evolved to tolerate hostile environmental conditions. We also address how stress and stress tolerance can lead to adaptation and have cascading effects on population- and community-level diversity. We argue that mycorrhizal fungal stress tolerance can strongly shape not only fungal and plant physiology, but also their ecology and evolution. We conclude by pointing out knowledge gaps and important future research directions required for both fully understanding stress tolerance in the mycorrhizal context and addressing ongoing environmental change.
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Affiliation(s)
- Sara Branco
- Department of Integrative Biology, University of Colorado Denver, Denver, CO, 80204, USA
| | - Annie Schauster
- Department of Integrative Biology, University of Colorado Denver, Denver, CO, 80204, USA
| | - Hui-Ling Liao
- North Florida Research and Education Center, University of Florida, Quincy, FL, 32351, USA
- Soil and Water Sciences Department, University of Florida, Gainesville, FL, 32611, USA
| | - Joske Ruytinx
- Research Groups Microbiology and Plant Genetics, Vrije Universiteit Brussel, 1050, Brussels, Belgium
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Kafle A, Cooney DR, Shah G, Garcia K. Mycorrhiza-mediated potassium transport in Medicago truncatula can be evaluated by using rubidium as a proxy. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2022; 322:111364. [PMID: 35760157 DOI: 10.1016/j.plantsci.2022.111364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 06/15/2022] [Accepted: 06/23/2022] [Indexed: 06/15/2023]
Abstract
Arbuscular mycorrhizal (AM) fungi considerably improve plant nutrient acquisition, particularly phosphorus and nitrogen. Despite the physiological importance of potassium (K+) in plants, there is increasing interest in the mycorrhizal contribution to plant K+ nutrition. Yet, methods to track K+ transport are often costly and limiting evaluation opportunities. Rubidium (Rb+) is known to be transported through same pathways as K+. As such our research efforts attempt to evaluate if Rb+ could serve as a viable proxy for evaluating K+ transport in AM symbiosis. Therefore, we examined the transport of K+ in Medicago truncatula colonized by the AM fungus Rhizophagus irregularis isolate 09 having access to various concentrations of Rb+ in custom-made two-compartment systems. Plant biomass, fungal root colonization, and shoot nutrient concentrations were recorded under sufficient and limited K+ regimes. We report that AM plants displayed higher shoot Rb+ and K+ concentrations and a greater K+:Na+ ratio relative to non-colonized plants in both sufficient and limited K+ conditions. Consequently, our results indicate that Rb+ can be used as a proxy to assess the movement of K+ in AM symbiosis, and suggest the existence of a mycorrhizal uptake pathway for K+ nutrition in M. truncatula.
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Affiliation(s)
- Arjun Kafle
- Department of Crop and Soil Sciences, North Carolina State University, Raleigh, NC 27695, USA
| | - Danielle R Cooney
- Department of Crop and Soil Sciences, North Carolina State University, Raleigh, NC 27695, USA
| | - Garud Shah
- Department of Crop and Soil Sciences, North Carolina State University, Raleigh, NC 27695, USA; Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC 27695, USA
| | - Kevin Garcia
- Department of Crop and Soil Sciences, North Carolina State University, Raleigh, NC 27695, USA.
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Koza NA, Adedayo AA, Babalola OO, Kappo AP. Microorganisms in Plant Growth and Development: Roles in Abiotic Stress Tolerance and Secondary Metabolites Secretion. Microorganisms 2022; 10:1528. [PMID: 36013946 PMCID: PMC9415082 DOI: 10.3390/microorganisms10081528] [Citation(s) in RCA: 52] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 07/19/2022] [Accepted: 07/25/2022] [Indexed: 11/23/2022] Open
Abstract
Crops aimed at feeding an exponentially growing population are often exposed to a variety of harsh environmental factors. Although plants have evolved ways of adjusting their metabolism and some have also been engineered to tolerate stressful environments, there is still a shortage of food supply. An alternative approach is to explore the possibility of using rhizosphere microorganisms in the mitigation of abiotic stress and hopefully improve food production. Several studies have shown that rhizobacteria and mycorrhizae organisms can help improve stress tolerance by enhancing plant growth; stimulating the production of phytohormones, siderophores, and solubilizing phosphates; lowering ethylene levels; and upregulating the expression of dehydration response and antioxidant genes. This article shows the secretion of secondary metabolites as an additional mechanism employed by microorganisms against abiotic stress. The understanding of these mechanisms will help improve the efficacy of plant-growth-promoting microorganisms.
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Affiliation(s)
- Ntombikhona Appear Koza
- Department of Biochemistry and Microbiology, University of Zululand, KwaDlangezwa 3886, South Africa
| | - Afeez Adesina Adedayo
- Food Security and Safety Focus Area, Faculty of Natural and Agricultural Science, North-West University, Mmabatho 2735, South Africa
| | - Olubukola Oluranti Babalola
- Food Security and Safety Focus Area, Faculty of Natural and Agricultural Science, North-West University, Mmabatho 2735, South Africa
| | - Abidemi Paul Kappo
- Molecular Biophysics and Structural Biology Group, Department of Biochemistry, University of Johannesburg, Auckland Park 2006, South Africa
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Frank HER, Garcia K. Benefits provided by four ectomycorrhizal fungi to Pinus taeda under different external potassium availabilities. MYCORRHIZA 2021; 31:755-766. [PMID: 34432129 DOI: 10.1007/s00572-021-01048-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Accepted: 08/13/2021] [Indexed: 06/13/2023]
Abstract
Ectomycorrhizal fungi contribute to the nutrition of many woody plants, including those in the Pinaceae family. Loblolly pine (Pinus taeda L.), a native species of the Southeastern USA, can be colonized by multiple species of ectomycorrhizal fungi. The role of these symbionts in P. taeda potassium (K+) nutrition has not been previously investigated. Here, we assessed the contribution of four ectomycorrhizal fungi, Hebeloma cylindrosporum, Paxillus ammoniavirescens, Laccaria bicolor, and Suillus cothurnatus, in P. taeda K+ acquisition under different external K+ availabilities. Using a custom-made two-compartment system, P. taeda seedlings were inoculated with one of the four fungi, or kept non-colonized, and grown under K+-limited or -sufficient conditions for 8 weeks. Only the fungi had access to separate compartments in which rubidium, an analog tracer for K+, was supplied before harvest. Resulting effects of the fungi were recorded, including root colonization, biomass, and nutrient concentrations. We also analyzed the fungal performance in axenic conditions under varying supply of K+ and sodium. Our study revealed that these four ectomycorrhizal fungi are differentially affected by external K+ and sodium variations, that they are not able to provide similar benefits to the host P. taeda in our growing conditions, and that rubidium may be used with some limitations to estimate K+ transport from ectomycorrhizal fungi to colonized plants.
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Affiliation(s)
- Hannah E R Frank
- Department of Crop and Soil Sciences, North Carolina State University, Raleigh, NC, 27695, USA
| | - Kevin Garcia
- Department of Crop and Soil Sciences, North Carolina State University, Raleigh, NC, 27695, USA.
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