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Rafique M, Naveed M, Mumtaz MZ, Niaz A, Alamri S, Siddiqui MH, Waheed MQ, Ali Z, Naman A, Rehman SU, Brtnicky M, Mustafa A. Unlocking the potential of biofilm-forming plant growth-promoting rhizobacteria for growth and yield enhancement in wheat (Triticum aestivum L.). Sci Rep 2024; 14:15546. [PMID: 38969785 PMCID: PMC11226629 DOI: 10.1038/s41598-024-66562-4] [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: 11/15/2023] [Accepted: 07/02/2024] [Indexed: 07/07/2024] Open
Abstract
Plant growth-promoting rhizobacteria (PGPR) boost crop yields and reduce environmental pressures through biofilm formation in natural climates. Recently, biofilm-based root colonization by these microorganisms has emerged as a promising strategy for agricultural enhancement. The current work aims to characterize biofilm-forming rhizobacteria for wheat growth and yield enhancement. For this, native rhizobacteria were isolated from the wheat rhizosphere and ten isolates were characterized for plant growth promoting traits and biofilm production under axenic conditions. Among these ten isolates, five were identified as potential biofilm-producing PGPR based on in vitro assays for plant growth-promoting traits. These were further evaluated under controlled and field conditions for their impact on wheat growth and yield attributes. Surface-enhanced Raman spectroscopy analysis further indicated that the biochemical composition of the biofilm produced by the selected bacterial strains includes proteins, carbohydrates, lipids, amino acids, and nucleic acids (DNA/RNA). Inoculated plants in growth chamber resulted in larger roots, shoots, and increase in fresh biomass than controls. Similarly, significant increases in plant height (13.3, 16.7%), grain yield (29.6, 17.5%), number of tillers (18.7, 34.8%), nitrogen content (58.8, 48.1%), and phosphorus content (63.0, 51.0%) in grains were observed in both pot and field trials, respectively. The two most promising biofilm-producing isolates were identified through 16 s rRNA partial gene sequencing as Brucella sp. (BF10), Lysinibacillus macroides (BF15). Moreover, leaf pigmentation and relative water contents were significantly increased in all treated plants. Taken together, our results revealed that biofilm forming PGPR can boost crop productivity by enhancing growth and physiological responses and thus aid in sustainable agriculture.
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Affiliation(s)
- Munazza Rafique
- Soil Bacteriology Section, Agricultural Biotechnology Research Institute, AARI, Faisalabad, 38000, Pakistan
| | - Muhammad Naveed
- Institute of Soil and Environmental Sciences, University of Agriculture, Faisalabad, 38040, Pakistan.
| | - Muhammad Zahid Mumtaz
- College of Agronomy, Gansu Agricultural University, Lanzhou 730070, China, Lahore, Pakistan
| | - Abid Niaz
- Soil Bacteriology Section, Agricultural Biotechnology Research Institute, AARI, Faisalabad, 38000, Pakistan
| | - Saud Alamri
- Department of Botany and Microbiology, College of Science, King Saud University, Riyadh, 11451, Saudi Arabia
| | - Manzer H Siddiqui
- Department of Botany and Microbiology, College of Science, King Saud University, Riyadh, 11451, Saudi Arabia
| | - Muhammad Qandeel Waheed
- Wheat Breeding Group, Plant Breeding and Genetics Division, Nuclear Institute for Agriculture and Biology (NIAB), Faisalabad, 38000, Pakistan
| | - Zulfiqar Ali
- Department of Plant Breeding and Genetics, University of Agriculture, Faisalabad, 38040, Pakistan
- Director, Programs and Projects Department, Islamic Organization for Food Security, 019900, Astana, Kazakhstan
| | - Abdul Naman
- Department of Chemistry, University of Agriculture, Faisalabad, 38040, Pakistan
| | - Sajid Ur Rehman
- Agricultural Biotechnology Research Institute, AARI, Faisalabad, 38000, Pakistan
| | - Martin Brtnicky
- Department of Agrochemistry, Soil Science, Microbiology and Plant Nutrition, Faculty of AgriSciences, Mendel University in Brno, Zemedelska 1, 61300, Brno, Czech Republic
| | - Adnan Mustafa
- Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China.
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Karthika S, Remya M, Varghese S, Dhanraj ND, Sali S, Rebello S, Jose SM, Jisha MS. Bacillus tequilensis PKDN31 and Bacillus licheniformis PKDL10 -As double headed swords to combat Fusarium oxysporum f. sp. lycopersici induced tomato wilt. Microb Pathog 2022; 172:105784. [PMID: 36122853 DOI: 10.1016/j.micpath.2022.105784] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Revised: 09/12/2022] [Accepted: 09/12/2022] [Indexed: 10/31/2022]
Abstract
Wilt disease, caused by Fusarium oxysporum. f. sp. lycopersici, is a global threat to tomato production that needs to be addressed seriously. The current research envisages the use of two self-compatible Bacillus strains, Bacillus tequilensis PKDN31 and Bacillus licheniformis PKDL10, in a combinatorial approach. The spent supernatant of liquid cultures from strains PKDN31 and PKDL10 showed in vitro antifungal activity against Fusarium sp. attaining an inhibition percentage of 95.33% and 96.54%, respectively. The bacterial isolates lytic activity against Fusarium oxysporum was evaluated by scanning electron microscopic analysis and lytic enzyme production of amylase, lipase, protease and β-1,3 glucanase. Furthermore, PKDN31 and PKDL10 produced siderophores and had root colonizing ability that enhanced the biocontrol efficiency. Combined in vivo inoculation of Bacillus tequilensis PKDN31 and Bacillus licheniformis PKDL10 on tomato seeds revealed that the strains could induce systemic resistance in tomato against Fusarium oxysporum. f. sp. lycopersici by increasing defence enzymes such as β-1,3 glucanase, polyphenol oxidase, peroxidase, phenylalanine ammonia-lyase, chitinase, and total phenol accumulations. Pot culture experiments also proved the biocontrol efficacy of the above dual culture supplementation as this treatment displayed a better growth as well as defense against Fusarium challenge compared to the controls. The obtained results suggest that rhizobacterial isolates could be employed as systemic resistance inducers and biocontrol agents in tomato plants to protect against Fusarium wilt disease.
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Affiliation(s)
- S Karthika
- School of Biosciences, Mahatma Gandhi University, Kottayam, Kerala, 686560, India
| | - M Remya
- School of Biosciences, Mahatma Gandhi University, Kottayam, Kerala, 686560, India
| | - Sherin Varghese
- School of Biosciences, Mahatma Gandhi University, Kottayam, Kerala, 686560, India
| | - N D Dhanraj
- School of Biosciences, Mahatma Gandhi University, Kottayam, Kerala, 686560, India
| | - Sangeeta Sali
- School of Biosciences, Mahatma Gandhi University, Kottayam, Kerala, 686560, India
| | - Sharrel Rebello
- National Institute of Plant Science Technology, Mahatma Gandhi University, Kottayam, Kerala, 686560, India
| | | | - M S Jisha
- School of Biosciences, Mahatma Gandhi University, Kottayam, Kerala, 686560, India; National Institute of Plant Science Technology, Mahatma Gandhi University, Kottayam, Kerala, 686560, India; School of Food Science and Technology, Mahatma Gandhi University, Kottayam, Kerala, 686560, India.
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Lu C, Wang Q, Jiang Y, Zhang M, Meng X, Li Y, Liu B, Yin Z, Liu H, Peng C, Li F, Yue Y, Hao M, Sui Y, Wang L, Cheng G, Liu J, Chu Z, Zhu C, Dong H, Ding X. Discovery of a novel nucleoside immune signaling molecule 2'-deoxyguanosine in microbes and plants. J Adv Res 2022; 46:1-15. [PMID: 35811061 PMCID: PMC10105077 DOI: 10.1016/j.jare.2022.06.014] [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: 03/13/2022] [Revised: 05/16/2022] [Accepted: 06/27/2022] [Indexed: 11/27/2022] Open
Abstract
INTRODUCTION Beneficial microorganisms play essential roles in plant growth and induced systemic resistance (ISR) by releasing signaling molecules. Our previous study obtained the crude extract from beneficial endophyte Paecilomyces variotii, termed ZNC (ZhiNengCong), which significantly enhanced plant resistance to pathogen even at 100 ng/ml. However, the immunoreactive components of ZNC remain unclear. Here, we further identified one of the immunoreactive components of ZNC is a nucleoside 2'-deoxyguanosine (2-dG). OBJECTIVES This paper intends to reveal the molecular mechanism of microbial-derived 2'-deoxyguanosine (2-dG) in activating plant immunity, and the role of plant-derived 2-dG in plant immunity. METHODS The components of ZNC were separated using a high-performance liquid chromatography (HPLC), and 2-dG is identified using a HPLC-mass spectrometry system (LC-MS). Transcriptome analysis and genetic experiments were used to reveal the immune signaling pathway dependent on 2-dG activation of plant immunity. RESULTS This study identified 2'-deoxyguanosine (2-dG) as one of the immunoreactive components from ZNC. And 2-dG significantly enhanced plant pathogen resistance even at 10 ng/ml (37.42 nM). Furthermore, 2-dG-induced resistance depends on NPR1, pattern-recognition receptors/coreceptors, ATP receptor P2K1 (DORN1), ethylene signaling but not salicylic acid accumulation. In addition, we identified Arabidopsis VENOSA4 (VEN4) was involved in 2-dG biosynthesis and could convert dGTP to 2-dG, and vne4 mutant plants were more susceptible to pathogens. CONCLUSION In summary, microbial-derived 2-dG may act as a novel immune signaling molecule involved in plant-microorganism interactions, and VEN4 is 2-dG biosynthesis gene and plays a key role in plant immunity.
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Affiliation(s)
- Chongchong Lu
- State Key Laboratory of Crop Biology, Shandong Provincial Key Laboratory for Biology of Vegetable Diseases and Insect Pests, College of Plant Protection, Shandong Agricultural University, Taian, Shandong 271018, China
| | - Qingbin Wang
- Shandong Pengbo Biotechnology Co., LTD, Taian 271018, China; National Engineering Laboratory for Efficient Utilization of Soil and Fertilizer Resources, College of Resources and Environment, Shandong Agricultural University, Taian, Shandong 271018, China
| | - Yanke Jiang
- State Key Laboratory of Crop Biology, Shandong Provincial Key Laboratory for Biology of Vegetable Diseases and Insect Pests, College of Plant Protection, Shandong Agricultural University, Taian, Shandong 271018, China
| | - Min Zhang
- National Engineering Laboratory for Efficient Utilization of Soil and Fertilizer Resources, College of Resources and Environment, Shandong Agricultural University, Taian, Shandong 271018, China
| | - Xuanlin Meng
- State Key Laboratory of Crop Biology, Shandong Provincial Key Laboratory for Biology of Vegetable Diseases and Insect Pests, College of Plant Protection, Shandong Agricultural University, Taian, Shandong 271018, China
| | - Yang Li
- State Key Laboratory of Crop Biology, Shandong Provincial Key Laboratory for Biology of Vegetable Diseases and Insect Pests, College of Plant Protection, Shandong Agricultural University, Taian, Shandong 271018, China
| | - Baoyou Liu
- State Key Laboratory of Crop Biology, Shandong Provincial Key Laboratory for Biology of Vegetable Diseases and Insect Pests, College of Plant Protection, Shandong Agricultural University, Taian, Shandong 271018, China
| | - Ziyi Yin
- State Key Laboratory of Crop Biology, Shandong Provincial Key Laboratory for Biology of Vegetable Diseases and Insect Pests, College of Plant Protection, Shandong Agricultural University, Taian, Shandong 271018, China
| | - Haifeng Liu
- State Key Laboratory of Crop Biology, Shandong Provincial Key Laboratory for Biology of Vegetable Diseases and Insect Pests, College of Plant Protection, Shandong Agricultural University, Taian, Shandong 271018, China
| | - Chune Peng
- State Key Laboratory of Crop Biology, Shandong Provincial Key Laboratory for Biology of Vegetable Diseases and Insect Pests, College of Plant Protection, Shandong Agricultural University, Taian, Shandong 271018, China
| | - Fuchuan Li
- National Glycoengineering Research Center and Shandong Key Laboratory of Carbohydrate Chemistry and Glycobiology, Shandong University, 72 Binhai Rd, Qingdao 266200, China
| | - Yingzhe Yue
- State Key Laboratory of Crop Biology, Shandong Provincial Key Laboratory for Biology of Vegetable Diseases and Insect Pests, College of Plant Protection, Shandong Agricultural University, Taian, Shandong 271018, China
| | - Mingxia Hao
- State Key Laboratory of Crop Biology, Shandong Provincial Key Laboratory for Biology of Vegetable Diseases and Insect Pests, College of Plant Protection, Shandong Agricultural University, Taian, Shandong 271018, China
| | - Yurong Sui
- State Key Laboratory of Crop Biology, Shandong Provincial Key Laboratory for Biology of Vegetable Diseases and Insect Pests, College of Plant Protection, Shandong Agricultural University, Taian, Shandong 271018, China
| | - Lulu Wang
- State Key Laboratory of Crop Biology, Shandong Provincial Key Laboratory for Biology of Vegetable Diseases and Insect Pests, College of Plant Protection, Shandong Agricultural University, Taian, Shandong 271018, China
| | - Guodong Cheng
- College of Veterinary Medicine, Shandong Agricultural University, Taian, Shandong 271018, China
| | - Jianzhu Liu
- College of Veterinary Medicine, Shandong Agricultural University, Taian, Shandong 271018, China
| | - Zhaohui Chu
- State Key Laboratory of Hybrid Rice, Hubei Hongshan Laboratory, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Changxiang Zhu
- State Key Laboratory of Crop Biology, Shandong Provincial Key Laboratory for Biology of Vegetable Diseases and Insect Pests, College of Plant Protection, Shandong Agricultural University, Taian, Shandong 271018, China
| | - Hansong Dong
- State Key Laboratory of Crop Biology, Shandong Provincial Key Laboratory for Biology of Vegetable Diseases and Insect Pests, College of Plant Protection, Shandong Agricultural University, Taian, Shandong 271018, China
| | - Xinhua Ding
- State Key Laboratory of Crop Biology, Shandong Provincial Key Laboratory for Biology of Vegetable Diseases and Insect Pests, College of Plant Protection, Shandong Agricultural University, Taian, Shandong 271018, China.
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Characterization of the major antifungal extrolite from rice endophyte Lysinibacillus sphaericus against Rhizoctonia solani. Arch Microbiol 2021; 203:2605-2613. [PMID: 33704544 DOI: 10.1007/s00203-021-02229-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 12/30/2020] [Accepted: 02/11/2021] [Indexed: 10/21/2022]
Abstract
Sheath blight of rice caused by Rhizoctonia solani is regarded as one of the most widely distributed diseases of rice, and is one of the major production constraints for rice in India and most rice-growing countries of Asia. Biological control of plant diseases using antagonistic bacteria is now considered as a promising alternative to the use of hazardous chemical fungicides or bactericides. Several bacterial endophytes have been reported to support growth and improve the health of the plants and therefore, may be important as biocontrol agents. In the present study, putative antifungal metabolites were extracted from rice foliage endophyte Lysinibacillus sphaericus KJ872548 by solvent extraction methods and purified using HPTLC techniques. Separated bands were subjected to assess the in vitro antagonistic activity toward rice sheath blight pathogen Rhizoctonia solani using a dual culture method. Partially purified active fraction B2 obtained from HPTLC analysis showed the highest percentage of inhibition (76.9%). GC MS and FTIR analyses of B2 revealed the compound as1, 2-Benzenedicarboxylic acid butyl 2-Ethylhexyl ester, a strong antifungal volatile organic compound. Light microscopic analysis of the fungal mycelium from the dual culture plate of both culture filtrate and 1, 2-Benzenedicarboxylic acid butyl 2-Ethylhexyl ester disclosed strong mycolytic activity as evident by mycelial distractions and shrinkage. This is the first report on antifungal production by endophytic Lysinibacillus sphaericus against R. solani, the rice sheath blight pathogen. The findings of this study biologically prospect the endophyte L. sphaericus as an inexpensive broad spectrum bioagent for eco-friendly, economic and sustainable agriculture.
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Divya K, Thampi M, Vijayan S, Varghese S, Jisha M. Induction of defence response in Oryza sativa L. against Rhizoctonia solani (Kuhn) by chitosan nanoparticles. Microb Pathog 2020; 149:104525. [DOI: 10.1016/j.micpath.2020.104525] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 09/15/2020] [Accepted: 09/21/2020] [Indexed: 11/29/2022]
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Onajobi IB, Idowu EO, Adeyemi JO, Samson OJ, Ogunyinka PI, Fagade OE. In vitro antibacterial activities and molecular characterization of bacterial species isolated from farmlands against selected pathogens. BIOTECHNOLOGY REPORTS (AMSTERDAM, NETHERLANDS) 2020; 27:e00513. [PMID: 32923377 PMCID: PMC7475235 DOI: 10.1016/j.btre.2020.e00513] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 06/09/2020] [Accepted: 07/31/2020] [Indexed: 04/12/2023]
Abstract
This study aims to screen bacterial isolates from Olabisi Onabanjo University Farmland for antibacterial activity against pathogenic microorganisms. Agar well diffusion method was used. Isolates were identified molecularly. Chi-square test revealed significant association between isolates, antibacterial activity with likelihood p-value = 0.000 and 5% significant level. Six among thirty-five isolates exhibited antibacterial activity against the test pathogenic species. A greater antibacterial activity (50 % inhibition) was observed in Lysinibacillus sphearicus strain PRE16. It inhibited the growth of Bacillus subtilis, Staphylococcus aureus and Escherichia coli by 23.00 ± 2.00, 18.00 ± 2.00 and 20.00 ± 4.00 respectively. DNA sequencing revealed antagonist isolates as Bacillus sp. BCN2, Brochothrix thermosphacta strain P30C4, Bacillus aryabhattai strain KNUC205, Alcaligenes faecalis strain KEM24, Bacillus arsenicus strain CSD05 and Lysinibacillus sphaericus strain PRE16. Phylogenetic analysis revealed close relatedness of most isolates with Bacillus species strains. These strains are suggested to be effective for the discovery of new antibacterial agents.
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Affiliation(s)
- Ismail B. Onajobi
- Department of Microbiology, Faculty of Science, Olabisi Onabanjo University, Ago-Iwoye, Ogun State, Nigeria
| | - Esther O. Idowu
- Department of Microbiology, Faculty of Science, Olabisi Onabanjo University, Ago-Iwoye, Ogun State, Nigeria
| | - Jamiu O. Adeyemi
- Department of Microbiology, Faculty of Science, Olabisi Onabanjo University, Ago-Iwoye, Ogun State, Nigeria
| | - Oyindamola J. Samson
- Department of Microbiology, Faculty of Science, Olabisi Onabanjo University, Ago-Iwoye, Ogun State, Nigeria
| | - Peter I. Ogunyinka
- Department of Mathematical Sciences, Faculty of Science, Olabisi Onabanjo University, Ago-Iwoye, Ogun State, Nigeria
| | - Obasola E. Fagade
- Department of Microbiology, Faculty of Science, University of Ibadan, Nigeria
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Pseudomonas taiwanensis (MTCC11631) mediated induction of systemic resistance in Anthurium andreanum L against blight disease and visualisation of defence related secondary metabolites using confocal laser scanning microscopy. BIOCATALYSIS AND AGRICULTURAL BIOTECHNOLOGY 2020. [DOI: 10.1016/j.bcab.2020.101561] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Karthika S, Midhun SJ, Jisha MS. A potential antifungal and growth-promoting bacterium Bacillus sp. KTMA4 from tomato rhizosphere. Microb Pathog 2020; 142:104049. [PMID: 32045643 DOI: 10.1016/j.micpath.2020.104049] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 02/07/2020] [Accepted: 02/07/2020] [Indexed: 10/25/2022]
Abstract
Plant growth-promoting rhizobacteria are indigenous beneficial bacteria that will enhance plant growth as well as suppress phytopathogens. In the present study, the isolate KTMA4 showed the highest inhibition against major phytopathogens of tomato; Fusarium oxysporum (66%) and Alternaria solani (54%) after seven days of incubation. Analysis of the 16S rRNA gene sequence revealed that the isolate KTMA4 is Bacillus cereus (MG547975). The isolate produced in vitro plants growth-promoting factors such as Indole-3-acetic acid, ammonia, catalase, siderophore and 1-aminocyclopropane-1-carboxylate deaminase and it has nitrogen fixation ability. The bacterial strain has also produced lytic enzymes such as amylase, cellulase, xylanase, lipase, and protease. Moreover, the bacterium Bacillus cereus KTMA4 effectively produced biofilm, biosurfactants and salt-tolerant (5% NaCl). The bacterium exhibited intrinsic antibiotic resistance. The in vivo studies using tomato plants grown from seeds treated with the bacterial strain KTMA4 demonstrated an enhancement in seed germination percentage (86.66 ± 2.88) and vigour index (637.5 ± 21.65) over the uninoculated control (germination percentage- 28.33 ± 2.88 and vigour index- 42.5 ± 4.33). 60 days of greenhouse study revealed that the bacterial isolate enhanced the plant growth significantly (P ≤ 0.05) compared to the uninoculated control and the treated plants. Therefore the study suggests that the newly isolated rhizosphere bacterial strain can be used as a potential biocontrol agent against a multitude of fungal pathogens as well as a biofertilizer inoculant for tomato cultivation.
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Affiliation(s)
- S Karthika
- School of Biosciences, Mahatma Gandhi University, Kottayam, Kerala, 686560, India
| | | | - M S Jisha
- School of Biosciences, Mahatma Gandhi University, Kottayam, Kerala, 686560, India.
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Chalivendra S, DeRobertis C, Reyes Pineda J, Ham JH, Damann K. Rice Phyllosphere Bacillus Species and Their Secreted Metabolites Suppress Aspergillus flavus Growth and Aflatoxin Production In Vitro and In Maize Seeds. Toxins (Basel) 2018; 10:toxins10040159. [PMID: 29659522 PMCID: PMC5923325 DOI: 10.3390/toxins10040159] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 04/09/2018] [Accepted: 04/11/2018] [Indexed: 12/15/2022] Open
Abstract
The emergence of super-toxigenic strains by recombination is a risk from an intensive use of intraspecific aflatoxin (AF) biocontrol agents (BCAs). Periodical alternation with interspecific-BCAs will be safer since they preclude recombination. We are developing an AF-biocontrol system using rice-associated Bacilli reported previously (RABs). More than 50% of RABs inhibited the growth of multiple A. flavus strains, with RAB4R being the most inhibitory and RAB1 among the least. The fungistatic activity of RAB4R is associated with the lysis of A. flavus hyphal tips. In field trails with the top five fungistatic RABs, RAB4R consistently inhibited AF contamination of maize by Tox4, a highly toxigenic A. flavus strain from Louisiana corn fields. RAB1 did not suppress A. flavus growth, but strongly inhibited AF production. Total and HPLC-fractionated lipopeptides (LPs) isolated from culture filtrates of RAB1 and RAB4R also inhibited AF accumulation. LPs were stable in vitro with little loss of activity even after autoclaving, indicating their potential field efficacy as a tank-mix application. A. flavus colonization and AF were suppressed in RAB1- or RAB4R-coated maize seeds. Since RAB4R provided both fungistatic and strong anti-mycotoxigenic activities in the laboratory and field, it can be a potent alternative to atoxigenic A. flavus strains. On the other hand, RAB1 may serve as an environmentally safe helper BCA with atoxigenic A. flavus strains, due its lack of strong fungistatic and hemolytic activities.
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Affiliation(s)
- Subbaiah Chalivendra
- Department of Plant Pathology and Crop Physiology, Louisiana State University AgCenter, Baton Rouge, LA 70803, USA.
| | - Catherine DeRobertis
- Department of Plant Pathology and Crop Physiology, Louisiana State University AgCenter, Baton Rouge, LA 70803, USA.
| | - Jorge Reyes Pineda
- Department of Plant Pathology and Crop Physiology, Louisiana State University AgCenter, Baton Rouge, LA 70803, USA.
| | - Jong Hyun Ham
- Department of Plant Pathology and Crop Physiology, Louisiana State University AgCenter, Baton Rouge, LA 70803, USA.
| | - Kenneth Damann
- Department of Plant Pathology and Crop Physiology, Louisiana State University AgCenter, Baton Rouge, LA 70803, USA.
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