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Qin X, Xu J, An X, Yang J, Wang Y, Dou M, Wang M, Huang J, Fu Y. Insight of endophytic fungi promoting the growth and development of woody plants. Crit Rev Biotechnol 2024; 44:78-99. [PMID: 36592988 DOI: 10.1080/07388551.2022.2129579] [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: 01/29/2022] [Revised: 04/04/2022] [Accepted: 04/16/2022] [Indexed: 01/04/2023]
Abstract
Microorganisms play an important role in plant growth and development. In particular, endophytic fungi is one of the important kinds of microorganisms and has a mutually beneficial symbiotic relationship with host plants. Endophytic fungi have many substantial benefits to host plants, especially for woody plants, such as accelerating plant growth, enhancing stress resistance, promoting nutrient absorption, resisting pathogens and etc. However, the effects of endophytic fungi on the growth and development of woody plants have not been systematically summarized. In this review, the functions of endophytic fungi for the growth and development of woody plants have been mainly reviewed, including regulating plant growth (e.g., flowering, root elongation, etc.) by producing nutrients and plant hormones, and improving plant disease, insect resistance and heavy metal resistance by producing secondary metabolites. In addition, the diversity of endophytic fungi could improve the ability of woody plants to adapt to adverse environment. The components produced by endophytic fungi have excellent potential for the growth and development of woody plants. This review has systematically discussed the potential regulation mechanism of endophytic fungi regulating the growth and development of woody plants, it would be of great significance for the development and utilization of endophytic fungi resource from woody plants for the protection of forest resources.
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Affiliation(s)
- Xiangyu Qin
- Key Laboratory of Forest Plant Ecology, Ministry of Education, Northeast Forestry University, Harbin, PR China
- College of Chemistry, Chemical Engineering and Resource Utilization, Northeast Forestry University, Harbin, PR China
| | - Jian Xu
- Key Laboratory of Forest Plant Ecology, Ministry of Education, Northeast Forestry University, Harbin, PR China
- College of Chemistry, Chemical Engineering and Resource Utilization, Northeast Forestry University, Harbin, PR China
| | - Xiaoli An
- Key Laboratory of Forest Plant Ecology, Ministry of Education, Northeast Forestry University, Harbin, PR China
- College of Chemistry, Chemical Engineering and Resource Utilization, Northeast Forestry University, Harbin, PR China
| | - Jie Yang
- Key Laboratory of Forest Plant Ecology, Ministry of Education, Northeast Forestry University, Harbin, PR China
- College of Chemistry, Chemical Engineering and Resource Utilization, Northeast Forestry University, Harbin, PR China
| | - Yao Wang
- Key Laboratory of Forest Plant Ecology, Ministry of Education, Northeast Forestry University, Harbin, PR China
- College of Chemistry, Chemical Engineering and Resource Utilization, Northeast Forestry University, Harbin, PR China
| | - Meijia Dou
- Key Laboratory of Forest Plant Ecology, Ministry of Education, Northeast Forestry University, Harbin, PR China
- College of Chemistry, Chemical Engineering and Resource Utilization, Northeast Forestry University, Harbin, PR China
| | - Minggang Wang
- The College of Forestry, Beijing Forestry University, Beijing, PR China
| | - Jin Huang
- Key Laboratory of Forest Plant Ecology, Ministry of Education, Northeast Forestry University, Harbin, PR China
- College of Chemistry, Chemical Engineering and Resource Utilization, Northeast Forestry University, Harbin, PR China
| | - Yujie Fu
- The College of Forestry, Beijing Forestry University, Beijing, PR China
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Shang XC, Cai X, Zhou Y, Han X, Zhang CS, Ilyas N, Li Y, Zheng Y. Pseudomonas Inoculation Stimulates Endophytic Azospira Population and Induces Systemic Resistance to Bacterial Wilt. FRONTIERS IN PLANT SCIENCE 2021; 12:738611. [PMID: 36406638 PMCID: PMC9673043 DOI: 10.3389/fpls.2021.738611] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Accepted: 08/19/2021] [Indexed: 06/04/2023]
Abstract
Bacterial communities in the rhizosphere play an important role in sustaining plant growth and the health of diverse soils. Recent studies have demonstrated that microbial keystone taxa in the rhizosphere microbial community are extremely critical for the suppression of diseases. However, the mechanisms involved in disease suppression by keystone species remain unclear. The present study assessed the effects of three Pseudomonas strains, which were identified as keystone species in our previous study, on the growth performance and root-associated bacterial community of tobacco plants. A high relative abundance of Ralstonia was found in the non-inoculated group, while a large Azospira population was observed in all groups inoculated with the three Pseudomonas strains. Correspondingly, the activities of the defense-related enzymes and the expression levels of the defense signaling marker genes of the plant were increased after inoculation with the Pseudomonas strains. Moreover, the correlation analyses showed that the relative abundance of Azospira, the activity of superoxide dismutase, catalase, and polyphenol oxidase, and the expression of H1N1, ACC Oxidase, and PR1 a/c had a significantly negative (p<0.05) relationship with the abundance of Ralstonia. This further revealed that the keystone species, such as Pseudomonas spp., can suppress bacterial wilt disease by enhancing the systemic resistance of tobacco plants.
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Affiliation(s)
- Xian-chao Shang
- Marine Agriculture Research Center, Tobacco Research Institute of Chinese Academy of Agricultural Sciences, Qingdao, China
- Graduate School of Chinese Academy of Agricultural Sciences, Beijing, China
| | - Xianjie Cai
- Shanghai Tobacco Group Co., Ltd., Shanghai, China
| | - Yanan Zhou
- Marine Agriculture Research Center, Tobacco Research Institute of Chinese Academy of Agricultural Sciences, Qingdao, China
| | - Xiaobin Han
- Biological Organic Fertilizer Engineering Technology Center of China Tobacco, Zunyi Branch of Guizhou Tobacco Company, Zunyi, China
| | - Cheng-Sheng Zhang
- Marine Agriculture Research Center, Tobacco Research Institute of Chinese Academy of Agricultural Sciences, Qingdao, China
| | - Naila Ilyas
- Marine Agriculture Research Center, Tobacco Research Institute of Chinese Academy of Agricultural Sciences, Qingdao, China
- Graduate School of Chinese Academy of Agricultural Sciences, Beijing, China
| | - Yiqiang Li
- Marine Agriculture Research Center, Tobacco Research Institute of Chinese Academy of Agricultural Sciences, Qingdao, China
| | - Yanfen Zheng
- Marine Agriculture Research Center, Tobacco Research Institute of Chinese Academy of Agricultural Sciences, Qingdao, China
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Varga T, Hixson KK, Ahkami AH, Sher AW, Barnes ME, Chu RK, Battu AK, Nicora CD, Winkler TE, Reno LR, Fakra SC, Antipova O, Parkinson DY, Hall JR, Doty SL. Endophyte-Promoted Phosphorus Solubilization in Populus. FRONTIERS IN PLANT SCIENCE 2020; 11:567918. [PMID: 33193494 PMCID: PMC7609660 DOI: 10.3389/fpls.2020.567918] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 09/25/2020] [Indexed: 05/24/2023]
Abstract
Phosphorus is one of the essential nutrients for plant growth, but it may be relatively unavailable to plants because of its chemistry. In soil, the majority of phosphorus is present in the form of a phosphate, usually as metal complexes making it bound to minerals or organic matter. Therefore, inorganic phosphate solubilization is an important process of plant growth promotion by plant associated bacteria and fungi. Non-nodulating plant species have been shown to thrive in low-nutrient environments, in some instances by relying on plant associated microorganisms called endophytes. These microorganisms live within the plant and help supply nutrients for the plant. Despite their potential enormous environmental importance, there are a limited number of studies looking at the direct molecular impact of phosphate solubilizing endophytic bacteria on the host plant. In this work, we studied the impact of two endophyte strains of wild poplar (Populus trichocarpa) that solubilize phosphate. Using a combination of x-ray imaging, spectroscopy methods, and proteomics, we report direct evidence of endophyte-promoted phosphorus uptake in poplar. We found that the solubilized phosphate may react and become insoluble once inside plant tissue, suggesting that endophytes may aid in the re-release of phosphate. Using synchrotron x-ray fluorescence spectromicroscopy, we visualized the nutrient phosphorus inside poplar roots inoculated by the selected endophytes and found the phosphorus in both forms of organic and inorganic phosphates inside the root. Tomography-based root imaging revealed a markedly different root biomass and root architecture for poplar samples inoculated with the phosphate solubilizing bacteria strains. Proteomics characterization on poplar roots coupled with protein network analysis revealed novel proteins and metabolic pathways with possible involvement in endophyte enriched phosphorus uptake. These findings suggest an important role of endophytes for phosphorus acquisition and provide a deeper understanding of the critical symbiotic associations between poplar and the endophytic bacteria.
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Affiliation(s)
- Tamas Varga
- Environmental Molecular Sciences Laboratory, Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA, United States
| | - Kim K. Hixson
- Environmental Molecular Sciences Laboratory, Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA, United States
| | - Amir H. Ahkami
- Environmental Molecular Sciences Laboratory, Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA, United States
| | - Andrew W. Sher
- School of Environmental and Forest Sciences, College of the Environment, University of Washington, Seattle, WA, United States
| | - Morgan E. Barnes
- Environmental Systems Graduate Group, University of California, Merced, Merced, CA, United States
| | - Rosalie K. Chu
- Environmental Molecular Sciences Laboratory, Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA, United States
| | - Anil K. Battu
- Environmental Molecular Sciences Laboratory, Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA, United States
| | - Carrie D. Nicora
- Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA, United States
| | - Tanya E. Winkler
- Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA, United States
| | - Loren R. Reno
- Environmental Molecular Sciences Laboratory, Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA, United States
| | - Sirine C. Fakra
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
| | - Olga Antipova
- Advanced Photon Source, Argonne National Laboratory, Lemont, IL, United States
| | - Dilworth Y. Parkinson
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
| | - Jackson R. Hall
- School of Environmental and Forest Sciences, College of the Environment, University of Washington, Seattle, WA, United States
| | - Sharon L. Doty
- School of Environmental and Forest Sciences, College of the Environment, University of Washington, Seattle, WA, United States
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Puri A, Padda KP, Chanway CP. Sustaining the growth of Pinaceae trees under nutrient-limited edaphic conditions via plant-beneficial bacteria. PLoS One 2020; 15:e0238055. [PMID: 32845898 PMCID: PMC7449467 DOI: 10.1371/journal.pone.0238055] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Accepted: 08/10/2020] [Indexed: 11/19/2022] Open
Abstract
Lodgepole pine, a prominent Pinaceae tree species native to western North America, is well-known for its ability to thrive in highly disturbed and degraded areas. One such area is the Sub-Boreal Pine-Spruce xeric-cold (SBPSxc) region in British Columbia, Canada, which is characterized by weakly-developed, parched soils that lack an organic forest floor and essential plant-available nutrients. We hypothesized that plant growth-promoting bacteria could play a significant role in sustaining the growth of lodgepole pine trees in the SBPSxc region. Testing this hypothesis, we evaluated plant growth-promoting abilities of six endophytic bacterial strains previously isolated from lodgepole pine trees growing in this region. These bacterial strains significantly enhanced the length and biomass of their natural host (lodgepole pine) as well as a foreign host (hybrid white spruce) in a 540-day long greenhouse trial. This growth stimulation could be linked to the diverse plant growth-promoting (PGP) abilities detected in these strains using in vitro assays for inorganic/organic phosphate-solubilization, siderophore production IAA production, ACC deaminase activity, lytic enzymes (chitinase, β-1,3-glucanase, protease, and cellulase) activity, ammonia production and catalase activity. ACC deaminase activity was also detected in vivo for all strains using ethylene-sensitive plants–canola and tomato. Notably, strains belonging to the Burkholderiaceae family (HP-S1r, LP-R1r and LP-R2r) showed the greatest potential in all PGP assays and enhanced pine and spruce seedling length and biomass by up to 1.5-fold and 4-fold, respectively. Therefore, such bacterial strains with multifarious PGP abilities could be crucial for survival and growth of lodgepole pine trees in the SBPSxc region and could potentially be utilized as bioinoculant for Pinaceae trees in highly disturbed and nutrient-poor ecosystems.
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Affiliation(s)
- Akshit Puri
- Faculty of Land and Food Systems, The University of British Columbia, Vancouver, British Columbia, Canada
- Department of Forest and Conservation Sciences, Faculty of Forestry, The University of British Columbia, Vancouver, British Columbia, Canada
- * E-mail:
| | - Kiran Preet Padda
- Faculty of Land and Food Systems, The University of British Columbia, Vancouver, British Columbia, Canada
- Department of Forest and Conservation Sciences, Faculty of Forestry, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Chris P. Chanway
- Faculty of Land and Food Systems, The University of British Columbia, Vancouver, British Columbia, Canada
- Department of Forest and Conservation Sciences, Faculty of Forestry, The University of British Columbia, Vancouver, British Columbia, Canada
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Menéndez E, Paço A. Is the Application of Plant Probiotic Bacterial Consortia Always Beneficial for Plants? Exploring Synergies between Rhizobial and Non-Rhizobial Bacteria and Their Effects on Agro-Economically Valuable Crops. Life (Basel) 2020; 10:E24. [PMID: 32178383 PMCID: PMC7151578 DOI: 10.3390/life10030024] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 03/03/2020] [Accepted: 03/09/2020] [Indexed: 12/13/2022] Open
Abstract
The overgrowth of human population and the demand for high-quality foods necessitate the search for sustainable alternatives to increase crop production. The use of biofertilizers, mostly based on plant probiotic bacteria (PPB), represents a reliable and eco-friendly solution. This heterogeneous group of bacteria possesses many features with positive effects on plants; however, how these bacteria with each other and with the environment when released into a field has still barely been studied. In this review, we focused on the diversity of root endophytic rhizobial and non-rhizobial bacteria existing within plant root tissues, and also on their potential applications as consortia exerting benefits for plants and the environment. We demonstrated the benefits of using bacterial inoculant consortia instead of single-strain inoculants. We then critically discussed several considerations that farmers, companies, governments, and the scientific community should take into account when a biofertilizer based on those PPBs is proposed, including (i) a proper taxonomic identification, (ii) the characterization of the beneficial features of PPB strains, and (iii) the ecological impacts on plants, environment, and plant/soil microbiomes. Overall, the success of a PPB consortium depends on many factors that must be considered and analyzed before its application as a biofertilizer in an agricultural system.
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Affiliation(s)
- Esther Menéndez
- MED—Mediterranean Institute for Agriculture, Environment and Development, Institute for Advanced Studies and Research (IIFA), University of Évora, Pólo da Mitra, Ap. 94, 7006-554 Évora, Portugal;
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Firrincieli A, Khorasani M, Frank AC, Doty SL. Influences of Climate on Phyllosphere Endophytic Bacterial Communities of Wild Poplar. FRONTIERS IN PLANT SCIENCE 2020; 11:203. [PMID: 32184800 PMCID: PMC7058686 DOI: 10.3389/fpls.2020.00203] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Accepted: 02/11/2020] [Indexed: 05/02/2023]
Abstract
Plant-associated microbial communities play a central role in the plant response to biotic and abiotic stimuli, improving plant fitness under challenging growing conditions. Many studies have focused on the characterization of changes in abundance and composition of root-associated microbial communities as a consequence of the plant response to abiotic factors such as altered soil nutrients and drought. However, changes in composition in response to abiotic factors are still poorly understood concerning the endophytic community associated to the phyllosphere, the above-ground plant tissues. In the present study, we applied high-throughput 16S rDNA gene sequencing of the phyllosphere endophytic bacterial communities colonizing wild Populus trichocarpa (black cottonwood) plants growing in native, nutrient-limited environments characterized by hot-dry (xeric) riparian zones (Yakima River, WA), riparian zones with mid hot-dry (Tieton and Teanaway Rivers, WA) and moist (mesic) climates (Snoqualmie, Skykomish and Skagit Rivers, WA). From sequencing data, 587 Amplicon Sequence Variants (ASV) were identified. Surprisingly, our data show that a core microbiome could be found in phyllosphere-associated endophytic communities in trees growing on opposite sides of the Cascades Mountain Range. Considering only taxa appearing in at least 90% of all samples within each climatic zone, the core microbiome was dominated only by two ASVs affiliated Pseudomonadaceae and two ASVs of the Enterobacteriaceae family. Alpha-diversity measures indicated that plants colonizing hot-dry environments showed a lower diversity than those from mid hot-dry and moist climates. Beta-diversity measures showed that bacterial composition was significantly different across sampling sites. Accordingly, we found that specific ASV affiliated to Pseudomonadaceae and Enterobacteriaceae were significantly more abundant in the phyllosphere endophytic community colonizing plants adapted to the xeric environment. In summary, this study highlights that sampling site is the major driver of variation and that only a few ASV showed a distribution that significantly correlated to climate variables.
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Affiliation(s)
- Andrea Firrincieli
- School of Environmental and Forest Sciences, College of the Environment, University of Washington, Seattle, WA, United States
| | - Mahsa Khorasani
- School of Environmental and Forest Sciences, College of the Environment, University of Washington, Seattle, WA, United States
| | - A. Carolin Frank
- Life & Environmental Sciences School of Natural Sciences, University of California, Merced, Merced, CA, United States
- Sierra Nevada Research Institute, School of Natural Sciences, University of California, Merced, Merced, CA, United States
| | - Sharon Lafferty Doty
- School of Environmental and Forest Sciences, College of the Environment, University of Washington, Seattle, WA, United States
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7
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Aghai MM, Khan Z, Joseph MR, Stoda AM, Sher AW, Ettl GJ, Doty SL. The Effect of Microbial Endophyte Consortia on Pseudotsuga menziesii and Thuja plicata Survival, Growth, and Physiology Across Edaphic Gradients. Front Microbiol 2019; 10:1353. [PMID: 31275276 PMCID: PMC6591459 DOI: 10.3389/fmicb.2019.01353] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Accepted: 05/31/2019] [Indexed: 11/17/2022] Open
Abstract
Increased frequency of droughts and degraded edaphic conditions decreases the success of many reforestation efforts in the Pacific Northwest. Microbial endophyte consortia have been demonstrated to contribute to plant growth promotion and protection from abiotic and biotic stresses – specifically drought conditions – across a number of food crops but for limited tree species. Our research aimed to investigate the potential to improve establishment of economically and ecologically important conifers through a series of in situ field trials and ex situ simulations. Microbial endophyte consortia from Salicaceae, previously shown to confer drought tolerance, and conifer endophyte strains with potentially symbiotic traits were selected for trials with Douglas-fir (Pseudotsuga menziesii) and western redcedar (Thuja plicata). Reductive experimentation was used to subject seedlings to a spectrum of simulated drought levels or presence/absence of fertilizer, testing hypotheses that endophyte consortia impart improved drought resistance and growth promotion, respectively. Inoculation from Salicaceae consortia significantly (p ≤ 0.05) improved survival among seedlings of both species subject to increasing drought stress, with T. plicata seedlings surviving at twofold higher rates in extreme drought conditions. Both species demonstrated improved growth 540 days after inoculation of seed with conifer derived consortia. In the carefully controlled greenhouse experiments with both species, seedling Fv/Fm and SPAD values remained significantly (p ≤ 0.05) more stable in inoculated treatment groups as stress increased. Our findings confirm that multi-strain consortia may be applied as seed or field amendment to conifers, and the approach is efficient in garnering a positive growth response and can mitigate abiotic stressors.
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Affiliation(s)
- Matthew M Aghai
- UW Center for Sustainable Forestry at Pack Forest, Eatonville, WA, United States.,School of Environmental and Forest Sciences, University of Washington, Seattle, WA, United States
| | - Zareen Khan
- School of Environmental and Forest Sciences, University of Washington, Seattle, WA, United States
| | - Matthew R Joseph
- School of Environmental and Forest Sciences, University of Washington, Seattle, WA, United States
| | - Aubrey M Stoda
- School of Environmental and Forest Sciences, University of Washington, Seattle, WA, United States
| | - Andrew W Sher
- School of Environmental and Forest Sciences, University of Washington, Seattle, WA, United States
| | - Gregory J Ettl
- UW Center for Sustainable Forestry at Pack Forest, Eatonville, WA, United States.,School of Environmental and Forest Sciences, University of Washington, Seattle, WA, United States
| | - Sharon L Doty
- School of Environmental and Forest Sciences, University of Washington, Seattle, WA, United States
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Randriamanana TR, Nissinen K, Ovaskainen A, Lavola A, Peltola H, Albrectsen B, Julkunen-Tiitto R. Does fungal endophyte inoculation affect the responses of aspen seedlings to carbon dioxide enrichment? FUNGAL ECOL 2018. [DOI: 10.1016/j.funeco.2017.12.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Rho H, Van Epps V, Wegley N, Doty SL, Kim SH. Salicaceae Endophytes Modulate Stomatal Behavior and Increase Water Use Efficiency in Rice. FRONTIERS IN PLANT SCIENCE 2018; 9:188. [PMID: 29552021 PMCID: PMC5840156 DOI: 10.3389/fpls.2018.00188] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Accepted: 01/31/2018] [Indexed: 05/18/2023]
Abstract
Bacterial and yeast endophytes isolated from the Salicaceae family have been shown to promote growth and alleviate stress in plants from different taxa. To determine the physiological pathways through which endophytes affect plant water relations, we investigated leaf water potential, whole-plant water use, and stomatal responses of rice plants to Salicaceae endophyte inoculation under CO2 enrichment and water deficit. Daytime stomatal conductance and stomatal density were lower in inoculated plants compared to controls. Leaf ABA concentrations increased with endophyte inoculation. As a result, transpirational water use decreased significantly with endophyte inoculation while biomass did not change or slightly increased. This response led to a significant increase in cumulative water use efficiency at harvest. Different endophyte strains produced the same results in host plant water relations and stomatal responses. These stomatal responses were also observed under elevated CO2 conditions, and the increase in water use efficiency was more pronounced under water deficit conditions. The effect on water use efficiency was positively correlated with daily light integrals across different experiments. Our results provide insights on the physiological mechanisms of plant-endophyte interactions involving plant water relations and stomatal functions.
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Affiliation(s)
- Hyungmin Rho
- School of Environmental and Forest Sciences, College of the Environment, University of Washington, Seattle, WA, United States
| | - Victor Van Epps
- Department of Biology, University of Washington, Seattle, WA, United States
| | - Nicholas Wegley
- School of Environmental and Forest Sciences, College of the Environment, University of Washington, Seattle, WA, United States
| | - Sharon L. Doty
- School of Environmental and Forest Sciences, College of the Environment, University of Washington, Seattle, WA, United States
| | - Soo-Hyung Kim
- School of Environmental and Forest Sciences, College of the Environment, University of Washington, Seattle, WA, United States
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10
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Kandel SL, Joubert PM, Doty SL. Bacterial Endophyte Colonization and Distribution within Plants. Microorganisms 2017; 5:E77. [PMID: 29186821 PMCID: PMC5748586 DOI: 10.3390/microorganisms5040077] [Citation(s) in RCA: 225] [Impact Index Per Article: 32.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Revised: 11/21/2017] [Accepted: 11/23/2017] [Indexed: 11/16/2022] Open
Abstract
The plant endosphere contains a diverse group of microbial communities. There is general consensus that these microbial communities make significant contributions to plant health. Both recently adopted genomic approaches and classical microbiology techniques continue to develop the science of plant-microbe interactions. Endophytes are microbial symbionts residing within the plant for the majority of their life cycle without any detrimental impact to the host plant. The use of these natural symbionts offers an opportunity to maximize crop productivity while reducing the environmental impacts of agriculture. Endophytes promote plant growth through nitrogen fixation, phytohormone production, nutrient acquisition, and by conferring tolerance to abiotic and biotic stresses. Colonization by endophytes is crucial for providing these benefits to the host plant. Endophytic colonization refers to the entry, growth and multiplication of endophyte populations within the host plant. Lately, plant microbiome research has gained considerable attention but the mechanism allowing plants to recruit endophytes is largely unknown. This review summarizes currently available knowledge about endophytic colonization by bacteria in various plant species, and specifically discusses the colonization of maize plants by Populus endophytes.
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Affiliation(s)
| | | | - Sharon L. Doty
- School of Environmental and Forest Sciences, College of the Environment, University of Washington, Seattle, WA 98195-2100, USA; (S.L.K.); (P.M.J.)
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12
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Kandel SL, Firrincieli A, Joubert PM, Okubara PA, Leston ND, McGeorge KM, Mugnozza GS, Harfouche A, Kim SH, Doty SL. An In vitro Study of Bio-Control and Plant Growth Promotion Potential of Salicaceae Endophytes. Front Microbiol 2017; 8:386. [PMID: 28348550 PMCID: PMC5347143 DOI: 10.3389/fmicb.2017.00386] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 02/23/2017] [Indexed: 11/13/2022] Open
Abstract
Microbial communities in the endosphere of Salicaceae plants, poplar (Populus trichocarpa) and willow (Salix sitchensis), have been demonstrated to be important for plant growth promotion, protection from biotic and abiotic stresses, and degradation of toxic compounds. Our study aimed to investigate bio-control activities of Salicaceae endophytes against various soil borne plant pathogens including Rhizoctonia solani AG-8, Fusarium culmorum, Gaeumannomyces graminis var. tritici, and Pythium ultimum. Additionally, different plant growth promoting traits such as biological nitrogen fixation (BNF), indole-3-acetic acid (IAA) biosynthesis, phosphate solubilization, and siderophore production were assessed in all bio-control positive strains. Burkholderia, Rahnella, Pseudomonas, and Curtobacterium were major endophyte genera that showed bio-control activities in the in-vitro assays. The bio-control activities of Burkholderia strains were stronger across all tested plant pathogens as compared to other stains. Genomes of sequenced Burkholderia strains WP40 and WP42 were surveyed to identify the putative genes involved in the bio-control activities. The ocf and hcnABC gene clusters responsible for biosynthesis of the anti-fungal metabolites, occidiofungin and hydrogen cyanide, are present in the genomes of WP40 and WP42. Nearly all endophyte strains showing the bio-control activities produced IAA, solubilized tricalcium phosphate, and synthesized siderophores in the culture medium. Moreover, some strains reduced acetylene into ethylene in the acetylene reduction assay, a common assay used for BNF. Salicaceae endophytes could be useful for bio-control of various plant pathogens, and plant growth promotion possibly through the mechanisms of BNF, IAA production, and nutrient acquisition.
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Affiliation(s)
- Shyam L Kandel
- School of Environmental and Forest Sciences, College of the Environment, University of Washington Seattle, WA, USA
| | - Andrea Firrincieli
- Department for Innovation in Biological, Agro-Food and Forest Systems, University of Tuscia Viterbo, Italy
| | - Pierre M Joubert
- Department of Biology, University of Washington Seattle, WA, USA
| | - Patricia A Okubara
- Wheat Health, Genetics and Quality Research Unit, USDA-ARS Pullman, WA, USA
| | - Natalie D Leston
- Department of Plant Pathology, Washington State University Pullman, WA, USA
| | - Kendra M McGeorge
- Department of Plant Pathology, Washington State University Pullman, WA, USA
| | - Giuseppe S Mugnozza
- Department for Innovation in Biological, Agro-Food and Forest Systems, University of Tuscia Viterbo, Italy
| | - Antoine Harfouche
- Department for Innovation in Biological, Agro-Food and Forest Systems, University of Tuscia Viterbo, Italy
| | - Soo-Hyung Kim
- School of Environmental and Forest Sciences, College of the Environment, University of Washington Seattle, WA, USA
| | - Sharon L Doty
- School of Environmental and Forest Sciences, College of the Environment, University of Washington Seattle, WA, USA
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Doty SL, Sher AW, Fleck ND, Khorasani M, Bumgarner RE, Khan Z, Ko AWK, Kim SH, DeLuca TH. Variable Nitrogen Fixation in Wild Populus. PLoS One 2016; 11:e0155979. [PMID: 27196608 PMCID: PMC4873266 DOI: 10.1371/journal.pone.0155979] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 05/06/2016] [Indexed: 11/18/2022] Open
Abstract
The microbiome of plants is diverse, and like that of animals, is important for overall health and nutrient acquisition. In legumes and actinorhizal plants, a portion of essential nitrogen (N) is obtained through symbiosis with nodule-inhabiting, N2-fixing microorganisms. However, a variety of non-nodulating plant species can also thrive in natural, low-N settings. Some of these species may rely on endophytes, microorganisms that live within plants, to fix N2 gas into usable forms. Here we report the first direct evidence of N2 fixation in the early successional wild tree, Populus trichocarpa, a non-leguminous tree, from its native riparian habitat. In order to measure N2 fixation, surface-sterilized cuttings of wild poplar were assayed using both 15N2 incorporation and the commonly used acetylene reduction assay. The 15N label was incorporated at high levels in a subset of cuttings, suggesting a high level of N-fixation. Similarly, acetylene was reduced to ethylene in some samples. The microbiota of the cuttings was highly variable, both in numbers of cultured bacteria and in genetic diversity. Our results indicated that associative N2-fixation occurred within wild poplar and that a non-uniformity in the distribution of endophytic bacteria may explain the variability in N-fixation activity. These results point to the need for molecular studies to decipher the required microbial consortia and conditions for effective endophytic N2-fixation in trees.
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Affiliation(s)
- Sharon L. Doty
- School of Environmental and Forest Sciences, College of the Environment, University of Washington, Seattle, Washington, United States of America
- * E-mail:
| | - Andrew W. Sher
- School of Environmental and Forest Sciences, College of the Environment, University of Washington, Seattle, Washington, United States of America
| | - Neil D. Fleck
- School of Environmental and Forest Sciences, College of the Environment, University of Washington, Seattle, Washington, United States of America
| | - Mahsa Khorasani
- School of Environmental and Forest Sciences, College of the Environment, University of Washington, Seattle, Washington, United States of America
| | - Roger E. Bumgarner
- Department of Microbiology, University of Washington, Seattle, Washington, United States of America
| | - Zareen Khan
- School of Environmental and Forest Sciences, College of the Environment, University of Washington, Seattle, Washington, United States of America
| | - Andrew W. K. Ko
- School of Environmental and Forest Sciences, College of the Environment, University of Washington, Seattle, Washington, United States of America
| | - Soo-Hyung Kim
- School of Environmental and Forest Sciences, College of the Environment, University of Washington, Seattle, Washington, United States of America
| | - Thomas H. DeLuca
- School of Environmental and Forest Sciences, College of the Environment, University of Washington, Seattle, Washington, United States of America
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