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Ali AO, Awla HK, Rashid TS. Investigating the in vivo biocontrol and growth-promoting efficacy of Bacillus sp. and Pseudomonas fluorescens against olive knot disease. Microb Pathog 2024; 191:106645. [PMID: 38631412 DOI: 10.1016/j.micpath.2024.106645] [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: 02/02/2024] [Revised: 04/04/2024] [Accepted: 04/11/2024] [Indexed: 04/19/2024]
Abstract
Olive knot disease, caused by Pseudomonas savastanoi, poses a significant threat to olive cultivation, necessitating sustainable alternatives to conventional chemical control. This study investigates the biocontrol effectiveness of Bacillus sp. (Og2) and Pseudomonas fluorescens (Oq5), alone and combined, against olive knot disease. Olive plants were sprayed with 5 ml of the bacteria until uniformly wet, with additional application to the soil surface. Pathogen injection occurred 24 h later. The results revealed that treating plants with a combination of both bacteria provided the highest reduction in disease severity (89.58 %), followed by P. fluorescens alone (69.38 %). Significant improvements were observed in shoot height, particularly with the combination of Bacillus sp. and P. fluorescens. The root length of olive seedlings treated with P. fluorescens and Bacillus sp., either alone or in combination, was significantly longer compared to the control and pathogen-treated seedlings. In terms of root dry weight, the most effective treatments were treated with P. fluorescens was the highest (82.94 g) among all treatments followed by the combination of both isolates with seedlings inoculated with P. savastanoi. These findings underscore the potential of Bacillus sp. and Pseudomonas fluorescens as effective biocontrol agents against olive knot disease and promoting olive seedlings growth, providing a sustainable and environmentally friendly approach to disease management.
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Affiliation(s)
- Avin Omer Ali
- Department of Plant Protection, College of Agricultural Engineering Sciences, Salahaddin University, Erbil, Iraq
| | | | - Tavga Sulaiman Rashid
- Department of Plant Protection, College of Agricultural Engineering Sciences, Salahaddin University, Erbil, Iraq.
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2
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Vergine M, Vita F, Casati P, Passera A, Ricciardi L, Pavan S, Aprile A, Sabella E, De Bellis L, Luvisi A. Characterization of the olive endophytic community in genotypes displaying a contrasting response to Xylella fastidiosa. BMC PLANT BIOLOGY 2024; 24:337. [PMID: 38664617 PMCID: PMC11044560 DOI: 10.1186/s12870-024-04980-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/08/2023] [Accepted: 04/03/2024] [Indexed: 04/29/2024]
Abstract
BACKGROUND Endophytes mediate the interactions between plants and other microorganisms, and the functional aspects of interactions between endophytes and their host that support plant-growth promotion and tolerance to stresses signify the ecological relevance of the endosphere microbiome. In this work, we studied the bacterial and fungal endophytic communities of olive tree (Olea europaea L.) asymptomatic or low symptomatic genotypes sampled in groves heavily compromised by Xylella fastidiosa subsp. pauca, aiming to characterize microbiota in genotypes displaying differential response to the pathogen. RESULTS The relationships between bacterial and fungal genera were analyzed both separately and together, in order to investigate the intricate correlations between the identified Operational Taxonomic Units (OTUs). Results suggested a dominant role of the fungal endophytic community compared to the bacterial one, and highlighted specific microbial taxa only associated with asymptomatic or low symptomatic genotypes. In addition, they indicated the occurrence of well-adapted genetic resources surviving after years of pathogen pressure in association with microorganisms such as Burkholderia, Quambalaria, Phaffia and Rhodotorula. CONCLUSIONS This is the first study to overview endophytic communities associated with several putatively resistant olive genotypes in areas under high X. fastidiosa inoculum pressure. Identifying these negatively correlated genera can offer valuable insights into the potential antagonistic microbial resources and their possible development as biocontrol agents.
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Affiliation(s)
- Marzia Vergine
- Department of Biological and Environmental Sciences and Technologies, University of Salento, Lecce, Italy
| | - Federico Vita
- Department of Biology, University of Bari "Aldo Moro", Bari, Italy.
| | - Paola Casati
- Department of Agricultural and Environmental Sciences, Production, Landscape, Agroenergy, University of Milan, Milano, Italy
| | - Alessandro Passera
- Department of Agricultural and Environmental Sciences, Production, Landscape, Agroenergy, University of Milan, Milano, Italy
| | - Luigi Ricciardi
- Department of Soil, Plant and Food Science, University of Bari "Aldo Moro", Bari, Italy
| | - Stefano Pavan
- Department of Soil, Plant and Food Science, University of Bari "Aldo Moro", Bari, Italy
| | - Alessio Aprile
- Department of Biological and Environmental Sciences and Technologies, University of Salento, Lecce, Italy
| | - Erika Sabella
- Department of Biological and Environmental Sciences and Technologies, University of Salento, Lecce, Italy
| | - Luigi De Bellis
- Department of Biological and Environmental Sciences and Technologies, University of Salento, Lecce, Italy
| | - Andrea Luvisi
- Department of Biological and Environmental Sciences and Technologies, University of Salento, Lecce, Italy
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3
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Singh S, Shyu DJH. Perspective on utilization of Bacillus species as plant probiotics for different crops in adverse conditions. AIMS Microbiol 2024; 10:220-238. [PMID: 38525044 PMCID: PMC10955172 DOI: 10.3934/microbiol.2024011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Revised: 02/21/2024] [Accepted: 02/22/2024] [Indexed: 03/26/2024] Open
Abstract
Plant probiotic bacteria are a versatile group of bacteria isolated from different environmental sources to improve plant productivity and immunity. The potential of plant probiotic-based formulations is successfully seen as growth enhancement in economically important plants. For instance, endophytic Bacillus species acted as plant growth-promoting bacteria, influenced crops such as cowpea and lady's finger, and increased phytochemicals in crops such as high antioxidant content in tomato fruits. The present review aims to summarize the studies of Bacillus species retaining probiotic properties and compare them with the conventional fertilizers on the market. Plant probiotics aim to take over the world since it is the time to rejuvenate and restore the soil and achieve sustainable development goals for the future. Comprehensive coverage of all the Bacillus species used to maintain plant health, promote plant growth, and fight against pathogens is crucial for establishing sustainable agriculture to face global change. Additionally, it will give the latest insight into this multifunctional agent with a detailed biocontrol mechanism and explore the antagonistic effects of Bacillus species in different crops.
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Affiliation(s)
- Shubhra Singh
- Department of Tropical Agriculture and International Cooperation, National Pingtung University of Science and Technology, Pingtung 912301, Taiwan
| | - Douglas J. H. Shyu
- Department of Biological Science and Technology, National Pingtung University of Science and Technology, Pingtung 912301, Taiwan
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4
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Cardoni M, Mercado-Blanco J. Confronting stresses affecting olive cultivation from the holobiont perspective. FRONTIERS IN PLANT SCIENCE 2023; 14:1261754. [PMID: 38023867 PMCID: PMC10661416 DOI: 10.3389/fpls.2023.1261754] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Accepted: 10/23/2023] [Indexed: 12/01/2023]
Abstract
The holobiont concept has revolutionized our understanding of plant-associated microbiomes and their significance for the development, fitness, growth and resilience of their host plants. The olive tree holds an iconic status within the Mediterranean Basin. Innovative changes introduced in olive cropping systems, driven by the increasing demand of its derived products, are not only modifying the traditional landscape of this relevant commodity but may also imply that either traditional or emerging stresses can affect it in ways yet to be thoroughly investigated. Incomplete information is currently available about the impact of abiotic and biotic pressures on the olive holobiont, what includes the specific features of its associated microbiome in relation to the host's structural, chemical, genetic and physiological traits. This comprehensive review consolidates the existing knowledge about stress factors affecting olive cultivation and compiles the information available of the microbiota associated with different olive tissues and organs. We aim to offer, based on the existing evidence, an insightful perspective of diverse stressing factors that may disturb the structure, composition and network interactions of the olive-associated microbial communities, underscoring the importance to adopt a more holistic methodology. The identification of knowledge gaps emphasizes the need for multilevel research approaches and to consider the holobiont conceptual framework in future investigations. By doing so, more powerful tools to promote olive's health, productivity and resilience can be envisaged. These tools may assist in the designing of more sustainable agronomic practices and novel breeding strategies to effectively face evolving environmental challenges and the growing demand of high quality food products.
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Affiliation(s)
- Martina Cardoni
- Departamento de Microbiología del Suelo y la Planta, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), Granada, Spain
| | - Jesús Mercado-Blanco
- Departamento de Microbiología del Suelo y la Planta, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), Granada, Spain
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Abuhena M, Al-Rashid J, Azim MF, Khan MNM, Kabir MG, Barman NC, Rasul NM, Akter S, Huq MA. Optimization of industrial (3000 L) production of Bacillus subtilis CW-S and its novel application for minituber and industrial-grade potato cultivation. Sci Rep 2022; 12:11153. [PMID: 35778426 PMCID: PMC9249890 DOI: 10.1038/s41598-022-15366-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 05/09/2022] [Indexed: 11/22/2022] Open
Abstract
A commercial plant probiotic product was developed employing Bacillus subtilis CW-S in submerged fermentation. The effects of molasses and urea on cell growth were investigated with the goal of low-cost manufacturing. Plackett–Burman and Central-Composite Design (CCD) were utilized to optimize production parameters to maximize productivity. The stability of the formulated product and its efficacy in cultivating minituber in aeroponics and industrial-grade potatoes in the field were assessed. The results showed that the medium BS10 (molasses and urea) produced satisfactory cell density (7.19 × 108 CFU/mL) as compared to the control (1.51 × 107 CFU/mL) and BS1-BS9 (expensive) media (1.84 × 107–1.37 × 109 CFU/mL). According to validated CCD results, optimized parameters fitted well in pilot (300 L; 2.05 × 109 CFU/mL) and industrial (3000 L; 2.01 × 109 CFU/mL) bioreactors, resulting in a two-fold increase in cell concentration over laboratory (9.84 × 108 CFU/mL) bioreactors. In aeroponics, CW-S produced excellent results, with a significant increase in the quantity and weight of minitubers and the survival rate of transplanted plantlets. In a field test, the yield of industrial-grade (> 55 mm) potatoes was increased with a reduction in fertilizer dose. Overall, the findings suggest that CW-S can be produced commercially utilizing the newly developed media and optimized conditions, making plant probiotics more cost-effective and accessible to farmers for crop cultivation, particularly in aeroponic minituber and industrial-grade potato production.
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Affiliation(s)
- Md Abuhena
- Department of Research and Development, Apex Biofertilizers and Biopesticides Limited, Gobindaganj, Gaibandha, 5740, Bangladesh
| | - Jubair Al-Rashid
- Department of Research and Development, Apex Biofertilizers and Biopesticides Limited, Gobindaganj, Gaibandha, 5740, Bangladesh.,Apex Biotechnology Laboratory, Apex Holdings Ltd., East Chandora, Shafipur, Kaliakoir, Gazipur, 1751, Bangladesh
| | - Md Faisal Azim
- Department of Research and Development, Apex Biofertilizers and Biopesticides Limited, Gobindaganj, Gaibandha, 5740, Bangladesh.
| | - Md Niuz Morshed Khan
- Apex Biotechnology Laboratory, Apex Holdings Ltd., East Chandora, Shafipur, Kaliakoir, Gazipur, 1751, Bangladesh
| | - Md Golam Kabir
- Department of Research and Development, Apex Biofertilizers and Biopesticides Limited, Gobindaganj, Gaibandha, 5740, Bangladesh.,Apex Biotechnology Laboratory, Apex Holdings Ltd., East Chandora, Shafipur, Kaliakoir, Gazipur, 1751, Bangladesh
| | - Nirmal Chandra Barman
- Apex Biotechnology Laboratory, Apex Holdings Ltd., East Chandora, Shafipur, Kaliakoir, Gazipur, 1751, Bangladesh
| | - Noorain Munim Rasul
- Department of Research and Development, Apex Biofertilizers and Biopesticides Limited, Gobindaganj, Gaibandha, 5740, Bangladesh.,Apex Biotechnology Laboratory, Apex Holdings Ltd., East Chandora, Shafipur, Kaliakoir, Gazipur, 1751, Bangladesh
| | - Shahina Akter
- Department of Food Science and Biotechnology, College of BioNano Technology, Gachon University, Seongnam, 461-701, Republic of Korea.
| | - Md Amdadul Huq
- Department of Food and Nutrition, College of Biotechnology and Natural Resource, Chung-Ang University, Anseong, Gyeonggi-do, 17546, Republic of Korea.
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6
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Zhao M, Liu D, Liang Z, Huang K, Wu X. Antagonistic activity of Bacillus subtilis CW14 and its β-glucanase against Aspergillus ochraceus. Food Control 2022. [DOI: 10.1016/j.foodcont.2021.108475] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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Mina D, Pereira JA, Lino-Neto T, Baptista P. Screening the Olive Tree Phyllosphere: Search and Find Potential Antagonists Against Pseudomonas savastanoi pv. savastanoi. Front Microbiol 2020; 11:2051. [PMID: 32983037 PMCID: PMC7477298 DOI: 10.3389/fmicb.2020.02051] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 08/05/2020] [Indexed: 02/02/2023] Open
Abstract
Olive knot (OK) is a widespread bacterial disease, caused by Pseudomonas savastanoi pv. savastanoi (Pss), which currently has not effective control methods. The use of naturally occurring microbial antagonists, such as bacteria, as biocontrol agents could be a strategy to manage this disease. The objective of this work was to select bacteria from olive tree phyllosphere able to antagonize Pss using in vitro and in planta experiments. The elucidation of their modes of action and the potential relationship between antagonism and bacteria origin has been investigated, as well. To this end, 60 bacterial isolates obtained from the surface and inner tissues of different organs (leaves, twigs, and knots), from two olive cultivars of varying susceptibilities to OK, were screened for their in vitro antagonistic effect against Pss. A total of 27 bacterial strains were able to significantly inhibit Pss growth, being this effect linked to bacteria origin. Strains from OK-susceptible cultivar and colonizing the surface of plant tissues showed the strongest antagonistic potential. The antagonistic activity was potentially due to the production of volatile compounds, siderophores and lytic enzymes. Bacillus amyloliquefaciens P41 was the most effective antagonistic strain and their capacity to control OK disease was subsequently assayed using in planta experiments. This strain significantly reduces OK disease severity (43.7%), knots weight (55.4%) and population size of Pss (26.8%), while increasing the shoot dry weight (55.0%) and root water content (39.6%) of Pss-infected olive plantlets. Bacterial isolates characterized in this study, in particular B. amyloliquefaciens P41, may be considered as promising biocontrol candidates for controlling OK disease.
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Affiliation(s)
- Diogo Mina
- Centro de Investigação de Montanha (CIMO), Instituto Politécnico de Bragança, Bragança, Portugal
| | - José Alberto Pereira
- Centro de Investigação de Montanha (CIMO), Instituto Politécnico de Bragança, Bragança, Portugal
| | - Teresa Lino-Neto
- BioSystems & Integrative Sciences Institute (BioISI), Plant Functional Biology Centre, University of Minho, Braga, Portugal
| | - Paula Baptista
- Centro de Investigação de Montanha (CIMO), Instituto Politécnico de Bragança, Bragança, Portugal
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8
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Impact of plant genotype and plant habitat in shaping bacterial pathobiome: a comparative study in olive tree. Sci Rep 2020; 10:3475. [PMID: 32103149 PMCID: PMC7044170 DOI: 10.1038/s41598-020-60596-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 01/31/2020] [Indexed: 12/02/2022] Open
Abstract
Plant-inhabiting microorganisms interact directly with each other affecting disease progression. However, the role of host plant and plant habitat in shaping pathobiome composition and their implication for host susceptibility/resistance to a particular disease are currently unknown. For the elucidation of these questions, both epiphytic and endophytic bacterial communities, present in asymptomatic and symptomatic twigs from olive cultivars displaying different susceptibilities to olive knot (OK) disease, were investigated using culturing methods. OK disease was the main driver of the bacterial community, causing changes on their diversity, abundance and composition. OK disease effect was most notorious on OK-susceptible cultivar and when considering the endophytic communities. Plant habitat (epiphytes vs. endophytes) also contributed to the bacterial community assembling, in particular on symptomatic twigs (knots) of OK-susceptible cultivar. In contrast, host cultivar had little effect on the bacterial community composition, but OK-symptomatic twigs (knots) revealed to be more affected by this driver. Overall, the pathobiome seems to result from an intricate interaction between the pathogen, the resident bacteria, and the plant host. Specific bacterial genera were associated to the presence or absence of OK disease in each cultivar. Their ability to trigger and/or suppress disease should be studied in the future.
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9
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Abdelshafy Mohamad OA, Ma JB, Liu YH, Zhang D, Hua S, Bhute S, Hedlund BP, Li WJ, Li L. Beneficial Endophytic Bacterial Populations Associated With Medicinal Plant Thymus vulgaris Alleviate Salt Stress and Confer Resistance to Fusarium oxysporum. FRONTIERS IN PLANT SCIENCE 2020; 11:47. [PMID: 32117385 PMCID: PMC7033553 DOI: 10.3389/fpls.2020.00047] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2019] [Accepted: 01/14/2020] [Indexed: 05/20/2023]
Abstract
As a result of climate change, salinity has become a major abiotic stress that reduces plant growth and crop productivity worldwide. A variety of endophytic bacteria alleviate salt stress; however, their ecology and biotechnological potential has not been fully realized. To address this gap, a collection of 117 endophytic bacteria were isolated from wild populations of the herb Thymus vulgaris in Sheikh Zuweid and Rafah of North Sinai Province, Egypt, and identified based on their 16S rRNA gene sequences. The endophytes were highly diverse, including 17 genera and 30 species. The number of bacterial species obtained from root tissues was higher (n = 18) compared to stem (n = 14) and leaf (n = 11) tissue. The endophytic bacteria exhibited several plant growth-promoting activities in vitro, including auxin synthesis, diazotrophy, phosphate solubilization, siderophore production, and production of lytic enzymes (i.e., chitinase, cellulase, protease, and lipase). Three endophytes representing Bacillus species associated with T. vulgaris such as EGY05, EGY21, and EGY25 were selected based on their ex-situ activities for growth chamber assays to test for their ability to promote the growth of tomato (Solanum lycopersicum L.) under various NaCl concentrations (50-200 mM). All three strains significantly (P < 0.05) promoted the growth of tomato plants under salt stress, compared to uninoculated controls. In addition, inoculated tomato plants by all tested strains decreased (P < 0.05) the activity of antioxidant enzymes (superoxide dismutase, catalase, and peroxidase). Six strains, representing Bacillus and Enterobacter species EGY01, EGY05, EGY16, EGY21, EGY25, and EGY31 were selected based on in vitro antagonistic activity to F. oxysporum for pot experiments under salt stress. All tested strains reduced the disease severity index (DSI) of tomato plants at all tested salt concentrations. Gas-chromatography/mass-spectrometry analysis of cell-free extracts of B. subtilis (EGY16) showed at least ten compounds were known to have antimicrobial activity, with the major peaks being benzene, 1,3-dimethyl-, p-xylene, dibutyl phthalate, bis (2-ethylhexyl) phthalate, and tetracosane. This study demonstrates that diverse endophytes grow in wild thyme populations and that some are able to alleviate salinity stress and inhibit F. oxysporum pathogenesis, making them promising candidates for biofertilizers and biocontrol agents.
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Affiliation(s)
- Osama Abdalla Abdelshafy Mohamad
- CAS Key Laboratory of Biogeography and Bioresource in Arid Land, Xinjiang Institute of Ecology and Geography, Urumqi, China
- Department of Biological, Marine Sciences, and Environmental Agriculture, Institute for Post Graduate Environmental Studies, Arish University, Al-Arish, Egypt
- Department of Environmental Protection, Faculty of Environmental Agricultural Sciences, Arish University, Al-Arish, Egypt
| | - Jin-Biao Ma
- CAS Key Laboratory of Biogeography and Bioresource in Arid Land, Xinjiang Institute of Ecology and Geography, Urumqi, China
| | - Yong-Hong Liu
- CAS Key Laboratory of Biogeography and Bioresource in Arid Land, Xinjiang Institute of Ecology and Geography, Urumqi, China
| | - Daoyuan Zhang
- CAS Key Laboratory of Biogeography and Bioresource in Arid Land, Xinjiang Institute of Ecology and Geography, Urumqi, China
| | - Shao Hua
- CAS Key Laboratory of Biogeography and Bioresource in Arid Land, Xinjiang Institute of Ecology and Geography, Urumqi, China
| | - Shrikant Bhute
- Department of Environmental Protection, Faculty of Environmental Agricultural Sciences, Arish University, Al-Arish, Egypt
| | - Brian P. Hedlund
- School of Life Sciences, University of Nevada, Las Vegas, NV, United States
| | - Wen-Jun Li
- CAS Key Laboratory of Biogeography and Bioresource in Arid Land, Xinjiang Institute of Ecology and Geography, Urumqi, China
- State Key Laboratory of Biocontrol and Guangdong Provincial Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-Sen University, Guangzhou, China
| | - Li Li
- CAS Key Laboratory of Biogeography and Bioresource in Arid Land, Xinjiang Institute of Ecology and Geography, Urumqi, China
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Radhakrishnan R, Hashem A, Abd_Allah EF. Bacillus: A Biological Tool for Crop Improvement through Bio-Molecular Changes in Adverse Environments. Front Physiol 2017; 8:667. [PMID: 28932199 PMCID: PMC5592640 DOI: 10.3389/fphys.2017.00667] [Citation(s) in RCA: 238] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Accepted: 08/22/2017] [Indexed: 02/05/2023] Open
Abstract
Crop productivity is affected by environmental and genetic factors. Microbes that are beneficial to plants are used to enhance the crop yield and are alternatives to chemical fertilizers and pesticides. Pseudomonas and Bacillus species are the predominant plant growth-promoting bacteria. The spore-forming ability of Bacillus is distinguished from that of Pseudomonas. Members of this genus also survive for a long time under unfavorable environmental conditions. Bacillus spp. secrete several metabolites that trigger plant growth and prevent pathogen infection. Limited studies have been conducted to understand the physiological changes that occur in crops in response to Bacillus spp. to provide protection against adverse environmental conditions. This review describes the current understanding of Bacillus-induced physiological changes in plants as an adaptation to abiotic and biotic stresses. During water scarcity, salinity and heavy metal accumulate in soil, Bacillus spp. produce exopolysaccharides and siderophores, which prevent the movement of toxic ions and adjust the ionic balance and water transport in plant tissues while controlling the pathogenic microbial population. In addition, the synthesis of indole-3-acetic acid, gibberellic acid and1-aminocyclopropane-1-carboxylate (ACC) deaminase by Bacillus regulates the intracellular phytohormone metabolism and increases plant stress tolerance. Cell-wall-degrading substances, such as chitosanase, protease, cellulase, glucanase, lipopeptides and hydrogen cyanide from Bacillus spp. damage the pathogenic bacteria, fungi, nematodes, viruses and pests to control their populations in plants and agricultural lands. The normal plant metabolism is affected by unfavorable environmental stimuli, which suppress crop growth and yield. Abiotic and biotic stress factors that have detrimental effects on crops are mitigated by Bacillus-induced physiological changes, including the regulation of water transport, nutrient up-take and the activation of the antioxidant and defense systems. Bacillus association stimulates plant immunity against stresses by altering stress-responsive genes, proteins, phytohormones and related metabolites. This review describes the beneficial effect of Bacillus spp. on crop plants, which improves plant productivity under unfavorable climatic conditions, and the current understanding of the mitigation mechanism of Bacillus spp. in stress-tolerant and/or stress-resistant plants.
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Affiliation(s)
| | - Abeer Hashem
- Botany and Microbiology Department, College of Science, King Saud UniversityRiyadh, Saudi Arabia
- Mycology and Plant Disease Survey Department, Plant Pathology Research InstituteGiza, Egypt
| | - Elsayed F. Abd_Allah
- Plant Production Department, College of Food and Agricultural Sciences, King Saud UniversityRiyadh, Saudi Arabia
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11
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Veras FF, Correa APF, Welke JE, Brandelli A. Inhibition of mycotoxin-producing fungi by Bacillus strains isolated from fish intestines. Int J Food Microbiol 2016; 238:23-32. [PMID: 27589021 DOI: 10.1016/j.ijfoodmicro.2016.08.035] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Revised: 08/09/2016] [Accepted: 08/25/2016] [Indexed: 11/17/2022]
Abstract
Bacillus strains isolated from the aquatic environment of the Brazilian Amazon region were tested for their activity against mycotoxigenic fungi. All tested bacteria showed antifungal activity, inhibiting at least 7 indicator fungi. Four Bacillus strains showing promising antifungal results were subsequently evaluated for their activity in reducing mycelial growth rate, sporulation, spore germination percentage, and mycotoxin production. Bacillus sp. P1 and Bacillus sp. P11 had a remarkable antifungal effect on toxigenic fungi. Washed bacterial cell suspension of strains P1 and P11 (107CFU/ml) reduced by >70% the fungal colony diameters, including a complete inhibition of ochratoxin A (OTA) producing Aspergillus spp. Significant reduction of growth rate, sporulation and spore germination were also observed. The bacteria influenced the production of mycotoxins, causing a reduction around 99 and 97% in AFB1 and OTA concentration, respectively. Chromatographic analysis revealed the presence of lipopeptides (iturin A and surfactin isomers) in butanol extracts of cell-free supernatants and cell pellets of strains P1 and P11. Furthermore, antifungal activity of these extracts was confirmed against A. flavus A12 and A. carbonarius ITAL293, producers of AFB1 and OTA, respectively. These bacterial strains could be promising biocontrol agents against toxigenic fungi.
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Affiliation(s)
- Flávio Fonseca Veras
- Laboratório de Bioquímica e Microbiologia Aplicada, Instituto de Ciência e Tecnologia de Alimentos, Universidade Federal do Rio Grande do Sul, 91501-970 Porto Alegre, Brazil
| | - Ana Paula Folmer Correa
- Laboratório de Bioquímica e Microbiologia Aplicada, Instituto de Ciência e Tecnologia de Alimentos, Universidade Federal do Rio Grande do Sul, 91501-970 Porto Alegre, Brazil
| | - Juliane Elisa Welke
- Laboratório de Bioquímica e Microbiologia Aplicada, Instituto de Ciência e Tecnologia de Alimentos, Universidade Federal do Rio Grande do Sul, 91501-970 Porto Alegre, Brazil
| | - Adriano Brandelli
- Laboratório de Bioquímica e Microbiologia Aplicada, Instituto de Ciência e Tecnologia de Alimentos, Universidade Federal do Rio Grande do Sul, 91501-970 Porto Alegre, Brazil.
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12
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Maldonado-González MM, Prieto P, Ramos C, Mercado-Blanco J. From the root to the stem: interaction between the biocontrol root endophyte Pseudomonas fluorescens PICF7 and the pathogen Pseudomonas savastanoi NCPPB 3335 in olive knots. Microb Biotechnol 2013; 6:275-87. [PMID: 23425069 PMCID: PMC3815922 DOI: 10.1111/1751-7915.12036] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Revised: 12/27/2012] [Accepted: 12/30/2012] [Indexed: 11/30/2022] Open
Abstract
Olive knot disease, caused by Pseudomonas savastanoi pv. savastanoi, is one of the most important biotic constraints for olive cultivation. Pseudomonas fluorescens PICF7, a natural colonizer of olive roots and effective biological control agent (BCA) against Verticillium wilt of olive, was examined as potential BCA against olive knot disease. Bioassays using in vitro-propagated olive plants were carried out to assess whether strain PICF7 controlled knot development either when co-inoculated with the pathogen in stems or when the BCA (in roots) and the pathogen (in stems) were spatially separated. Results showed that PICF7 was able to establish and persist in stem tissues upon artificial inoculation. While PICF7 was not able to suppress disease development, its presence transiently decreased pathogen population size, produced less necrotic tumours, and sharply altered the localization of the pathogen in the hyperplasic tissue, which may pose epidemiological consequences. Confocal laser scanning microscopy combined with fluorescent tagging of bacteria revealed that when PICF7 was absent the pathogen tended to be localized at the knot surface. However, presence of the BCA seemed to confine P. savastanoi at inner regions of the tumours. This approach has also enabled to prove that the pathogen can moved systemically beyond the hypertrophied tissue.
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Affiliation(s)
- M Mercedes Maldonado-González
- Departamento de Protección de Cultivos, Instituto de Agricultura Sostenible, Consejo Superior de Investigaciones Científicas (CSIC)Alameda del Obispo s/n, Apartado 4084, E-14080, Córdoba, Spain
| | - Pilar Prieto
- Departamento de Mejora Genética Vegetal, Instituto de Agricultura Sostenible, Consejo Superior de Investigaciones Científicas (CSIC)Alameda del Obispo s/n, Apartado 4084, E-14080, Córdoba, Spain
| | - Cayo Ramos
- Instituto de Hortofruticultura Subtropical y Mediterránea ‘La Mayora’, Universidad de Málaga-Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Área de Genética, Facultad de Ciencias, Universidad de MálagaCampus de Teatinos s/n, E-29071, Málaga, Spain
| | - Jesús Mercado-Blanco
- Departamento de Protección de Cultivos, Instituto de Agricultura Sostenible, Consejo Superior de Investigaciones Científicas (CSIC)Alameda del Obispo s/n, Apartado 4084, E-14080, Córdoba, Spain
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