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Higgins SA, Igwe DO, Coradetti S, Ramsey JS, DeBlasio SL, Pitino M, Shatters RG, Niedz R, Fleites LA, Heck M. Plant-Derived, Nodule-Specific Cysteine-Rich Peptides as a Novel Source of Biopesticides for Controlling Citrus Greening Disease. PHYTOPATHOLOGY 2024:PHYTO09230322KC. [PMID: 38376984 DOI: 10.1094/phyto-09-23-0322-kc] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/22/2024]
Abstract
Nodule-specific cysteine-rich (NCR) peptides, encoded in the genome of the Mediterranean legume Medicago truncatula (barrelclover), are known to regulate plant-microbe interactions. A subset of computationally derived 20-mer peptide fragments from 182 NCR peptides was synthesized to identify those with activity against the unculturable vascular pathogen associated with citrus greening disease, 'Candidatus Liberibacter asiaticus' (CLas). Grounded in a design of experiments framework, we evaluated the peptides in a screening pipeline involving three distinct assays: a bacterial culture assay with Liberibacter crescens, a CLas-infected excised citrus leaf assay, and an assay to evaluate effects on bacterial acquisition by the nymphal stage of hemipteran vector Diaphorina citri. A subset of the 20-mer NCR peptide fragments inhibits both CLas growth in citrus leaves and CLas acquisition by D. citri. Two peptides induced higher levels of D. citri mortality. These findings reveal 20-mer NCR peptides as a new class of plant-derived biopesticide molecules to control citrus greening disease.
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Affiliation(s)
- Steven A Higgins
- Emerging Pests and Pathogens Research Unit, U.S. Department of Agriculture-Agricultural Research Service, Ithaca, NY 14853
| | - David O Igwe
- Plant Pathology and Plant Microbe Interactions Section, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853
| | - Samuel Coradetti
- Emerging Pests and Pathogens Research Unit, U.S. Department of Agriculture-Agricultural Research Service, Ithaca, NY 14853
| | - John S Ramsey
- Emerging Pests and Pathogens Research Unit, U.S. Department of Agriculture-Agricultural Research Service, Ithaca, NY 14853
| | - Stacy L DeBlasio
- Emerging Pests and Pathogens Research Unit, U.S. Department of Agriculture-Agricultural Research Service, Ithaca, NY 14853
| | | | - Robert G Shatters
- U.S. Horticultural Research Laboratory, U.S. Department of Agriculture-Agricultural Research Service, Fort Pierce, FL 34945
| | - Randall Niedz
- U.S. Horticultural Research Laboratory, U.S. Department of Agriculture-Agricultural Research Service, Fort Pierce, FL 34945
| | - Laura A Fleites
- Emerging Pests and Pathogens Research Unit, U.S. Department of Agriculture-Agricultural Research Service, Ithaca, NY 14853
| | - Michelle Heck
- Emerging Pests and Pathogens Research Unit, U.S. Department of Agriculture-Agricultural Research Service, Ithaca, NY 14853
- Plant Pathology and Plant Microbe Interactions Section, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853
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2
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Wang H, Irigoyen S, Liu J, Ramasamy M, Padilla C, Bedre R, Yang C, Thapa SP, Mulgaonkar N, Ancona V, He P, Coaker G, Fernando S, Mandadi KK. Inhibition of a conserved bacterial dual-specificity phosphatase confers plant tolerance to Candidatus Liberibacter spp. iScience 2024; 27:109232. [PMID: 38425843 PMCID: PMC10904284 DOI: 10.1016/j.isci.2024.109232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Revised: 11/08/2023] [Accepted: 02/09/2024] [Indexed: 03/02/2024] Open
Abstract
"Candidatus Liberibacter spp." are insect-vectored, fastidious, and vascular-limited phytopathogens. They are the presumptive causal agents of potato zebra chip, tomato vein clearing, and the devastating citrus greening disease worldwide. There is an urgent need to develop new strategies to control them. In this study, we characterized a dual-specificity serine/tyrosine phosphatase (STP) that is well conserved among thirty-three geographically diverse "Candidatus Liberibacter spp." and strains that infect multiple Solanaceaea and citrus spp. The STP is expressed in infected plant tissues, localized at the plant cytosol and plasma membrane, and interferes with plant cell death responses. We employed an in silico target-based molecular modeling and ligand screen to identify two small molecules with high binding affinity to STP. Efficacy studies demonstrated that the two molecules can inhibit "Candidatus Liberibacter spp." but not unrelated pathogens and confer plant disease tolerance. The inhibitors and strategies are promising means to control "Candidatus Liberibacter spp."
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Affiliation(s)
- Haoqi Wang
- Biological and Agricultural Engineering Department, Texas A&M University, College Station, TX, USA
| | - Sonia Irigoyen
- Texas A&M AgriLife Research & Extension Center, Texas A&M University System, 2415 E. Highway 83, Weslaco TX 78596, USA
| | - Jiaxing Liu
- Texas A&M AgriLife Research & Extension Center, Texas A&M University System, 2415 E. Highway 83, Weslaco TX 78596, USA
| | - Manikandan Ramasamy
- Texas A&M AgriLife Research & Extension Center, Texas A&M University System, 2415 E. Highway 83, Weslaco TX 78596, USA
| | - Carmen Padilla
- Texas A&M AgriLife Research & Extension Center, Texas A&M University System, 2415 E. Highway 83, Weslaco TX 78596, USA
| | - Renesh Bedre
- Texas A&M AgriLife Research & Extension Center, Texas A&M University System, 2415 E. Highway 83, Weslaco TX 78596, USA
| | - Chuanyu Yang
- Department of Agriculture, Agribusiness, and Environmental Sciences, Texas A&M University-Kingsville, Citrus Center, Weslaco, TX, USA
| | - Shree P. Thapa
- Department of Plant Pathology, University of California, Davis, Davis, CA, USA
| | - Nirmitee Mulgaonkar
- Biological and Agricultural Engineering Department, Texas A&M University, College Station, TX, USA
| | - Veronica Ancona
- Department of Agriculture, Agribusiness, and Environmental Sciences, Texas A&M University-Kingsville, Citrus Center, Weslaco, TX, USA
| | - Ping He
- Department of Biochemistry and Biophysics, Texas A&M University, 2128 TAMU, College Station, TX, USA
| | - Gitta Coaker
- Department of Plant Pathology, University of California, Davis, Davis, CA, USA
| | - Sandun Fernando
- Biological and Agricultural Engineering Department, Texas A&M University, College Station, TX, USA
| | - Kranthi K. Mandadi
- Texas A&M AgriLife Research & Extension Center, Texas A&M University System, 2415 E. Highway 83, Weslaco TX 78596, USA
- Department of Plant Pathology and Microbiology, Texas A&M University, 2132 TAMU, College Station, TX, USA
- Institute for Advancing Health Through Agriculture, Texas A&M AgriLife, College Station, TX, USA
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3
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Zhang S, Wang X, He J, Zhang S, Zhao T, Fu S, Zhou C. A Sec-dependent effector, CLIBASIA_04425, contributes to virulence in ' Candidatus Liberibater asiaticus'. FRONTIERS IN PLANT SCIENCE 2023; 14:1224736. [PMID: 37554557 PMCID: PMC10405523 DOI: 10.3389/fpls.2023.1224736] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Accepted: 07/05/2023] [Indexed: 08/10/2023]
Abstract
Citrus Huanglongbing (HLB) is the most destructive citrus disease worldwide, mainly caused by 'Candidatus Liberibacter asiaticus' (CLas). It encodes a large number of Sec-dependent effectors that contribute to HLB progression. In this study, an elicitor triggering ROS burst and cell death in Nicotiana benthamiana, CLIBASIA_04425 (CLas4425), was identified. Of particular interest, its cell death-inducing activity is associated with its subcellular localization and the cytoplasmic receptor Botrytis-induced kinase 1 (BIK1). Compared with CLas infected psyllids, CLas4425 showed higher expression level in planta. The transient expression of CLas4425 in N. benthamiana and its overexpression in Citrus sinensis enhanced plant susceptibility to Pseudomonas syringae pv. tomato DC3000 ΔhopQ1-1 and CLas, respectively. Furthermore, the salicylic acid (SA) level along with the expression of genes NPR1/EDS1/NDR1/PRs in SA signal transduction was repressed in CLas4425 transgenic citrus plants. Taken together, CLas4425 is a virulence factor that promotes CLas proliferation, likely by interfering with SA-mediated plant immunity. The results obtained facilitate our understanding of CLas pathogenesis.
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Affiliation(s)
- Shushe Zhang
- Citrus Research Institute, Southwest University/National Citrus Engineering Research Center, Chongqing, China
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Chinese Academy of Agriculture Sciences, Institute of Plant Protection, Beijing, China
| | - Xuefeng Wang
- Citrus Research Institute, Southwest University/National Citrus Engineering Research Center, Chongqing, China
| | - Jun He
- Citrus Research Institute, Southwest University/National Citrus Engineering Research Center, Chongqing, China
| | - Song Zhang
- Guangxi Citrus Breeding and Cultivation Engineering Technology Center Academy of Specialty Crops, Guangxi, Guilin, China
| | - Tingchang Zhao
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Chinese Academy of Agriculture Sciences, Institute of Plant Protection, Beijing, China
| | - Shimin Fu
- Citrus Research Institute, Southwest University/National Citrus Engineering Research Center, Chongqing, China
| | - Changyong Zhou
- Citrus Research Institute, Southwest University/National Citrus Engineering Research Center, Chongqing, China
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4
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Kennedy JP, Wood K, Pitino M, Mandadi K, Igwe DO, Shatters RG, Widmer TL, Niedz R, Heck M. A Perspective on Current Therapeutic Molecule Screening Methods Against ' Candidatus Liberibacter asiaticus', the Presumed Causative Agent of Citrus Huanglongbing. PHYTOPATHOLOGY 2023; 113:1171-1179. [PMID: 36750555 DOI: 10.1094/phyto-12-22-0455-per] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Huanglongbing (HLB), referred to as citrus greening disease, is a bacterial disease impacting citrus production worldwide and is fatal to young trees and mature trees of certain varieties. In some areas, the disease is devastating the citrus industry. A successful solution to HLB will be measured in economics: citrus growers need treatments that improve tree health, fruit production, and most importantly, economic yield. The profitability of citrus groves is the ultimate metric that truly matters when searching for solutions to HLB. Scientific approaches used in the laboratory, greenhouse, or field trials are critical to the discovery of those solutions and to estimate the likelihood of success of a treatment aimed at commercialization. Researchers and the citrus industry use a number of proxy evaluations of potential HLB solutions; understanding the strengths and limitations of each assay, as well as how best to compare different assays, is critical for decision-making to advance therapies into field trials and commercialization. This perspective aims to help the reader compare and understand the limitations of different proxy evaluation systems based on the treatment and evaluation under consideration. The researcher must determine the suitability of one or more of these metrics to identify treatments and predict the usefulness of these treatments in having an eventual impact on citrus production and HLB mitigation. As therapies advance to field trials in the next few years, a reevaluation of these metrics will be useful to guide future research efforts on strategies to mitigate HLB and vascular bacterial pathogens in other perennial crops.
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Affiliation(s)
- John Paul Kennedy
- U.S. Horticultural Research Laboratory, U.S. Department of Agriculture-Agricultural Research Service, Fort Pierce, FL 34945
| | | | | | - Kranthi Mandadi
- Department of Plant Pathology and Microbiology, Texas A&M AgriLife Research and Extension Center, Weslaco, TX 78596
- Texas A&M AgriLife Institute for Advancing Health Through Agriculture, Texas A&M AgriLife, College Station, TX 77843
| | - David O Igwe
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853
| | - Robert G Shatters
- U.S. Horticultural Research Laboratory, U.S. Department of Agriculture-Agricultural Research Service, Fort Pierce, FL 34945
| | - Timothy L Widmer
- U.S. Department of Agriculture-Agricultural Research Service, Beltsville, MD 20705
| | - Randall Niedz
- U.S. Horticultural Research Laboratory, U.S. Department of Agriculture-Agricultural Research Service, Fort Pierce, FL 34945
| | - Michelle Heck
- Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853
- Emerging Pests and Pathogens Research Unit, U.S. Department of Agriculture-Agricultural Research Service, Ithaca, NY 14853
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5
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Batarseh TN, Batarseh SN, Morales-Cruz A, Gaut BS. Comparative genomics of the Liberibacter genus reveals widespread diversity in genomic content and positive selection history. Front Microbiol 2023; 14:1206094. [PMID: 37434713 PMCID: PMC10330825 DOI: 10.3389/fmicb.2023.1206094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 06/09/2023] [Indexed: 07/13/2023] Open
Abstract
'Candidatus Liberibacter' is a group of bacterial species that are obligate intracellular plant pathogens and cause Huanglongbing disease of citrus trees and Zebra Chip in potatoes. Here, we examined the extent of intra- and interspecific genetic diversity across the genus using comparative genomics. Our approach examined a wide set of Liberibacter genome sequences including five pathogenic species and one species not known to cause disease. By performing comparative genomics analyses, we sought to understand the evolutionary history of this genus and to identify genes or genome regions that may affect pathogenicity. With a set of 52 genomes, we performed comparative genomics, measured genome rearrangement, and completed statistical tests of positive selection. We explored markers of genetic diversity across the genus, such as average nucleotide identity across the whole genome. These analyses revealed the highest intraspecific diversity amongst the 'Ca. Liberibacter solanacearum' species, which also has the largest plant host range. We identified sets of core and accessory genes across the genus and within each species and measured the ratio of nonsynonymous to synonymous mutations (dN/dS) across genes. We identified ten genes with evidence of a history of positive selection in the Liberibacter genus, including genes in the Tad complex, which have been previously implicated as being highly divergent in the 'Ca. L. capsica' species based on high values of dN.
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Affiliation(s)
| | - Sarah N. Batarseh
- Department of Plant and Microbial Biology, UC Berkeley, Berkeley, CA, United States
| | - Abraham Morales-Cruz
- U.S. Department of Energy, Joint Genome Institute, Lawrence Berkeley National Lab, Berkeley, CA, United States
| | - Brandon S. Gaut
- Department of Ecology and Evolutionary Biology, UC Irvine, Irvine, CA, United States
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6
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Patwardhan S, Phan J, Smedile F, Vetriani C. The Genome of Varunaivibrio sulfuroxidans Strain TC8 T, a Metabolically Versatile Alphaproteobacterium from the Tor Caldara Gas Vents in the Tyrrhenian Sea. Microorganisms 2023; 11:1366. [PMID: 37374867 DOI: 10.3390/microorganisms11061366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 05/02/2023] [Accepted: 05/15/2023] [Indexed: 06/29/2023] Open
Abstract
Varunaivibrio sulfuroxidans type strain TC8T is a mesophilic, facultatively anaerobic, facultatively chemolithoautotrophic alphaproteobacterium isolated from a sulfidic shallow-water marine gas vent located at Tor Caldara, Tyrrhenian Sea, Italy. V. sulfuroxidans belongs to the family Thalassospiraceae within the Alphaproteobacteria, with Magnetovibrio blakemorei as its closest relative. The genome of V. sulfuroxidans encodes the genes involved in sulfur, thiosulfate and sulfide oxidation, as well as nitrate and oxygen respiration. The genome encodes the genes involved in carbon fixation via the Calvin-Benson-Bassham cycle, in addition to genes involved in glycolysis and the TCA cycle, indicating a mixotrophic lifestyle. Genes involved in the detoxification of mercury and arsenate are also present. The genome also encodes a complete flagellar complex, one intact prophage and one CRISPR, as well as a putative DNA uptake mechanism mediated by the type IVc (aka Tad pilus) secretion system. Overall, the genome of Varunaivibrio sulfuroxidans highlights the organism's metabolic versatility, a characteristic that makes this strain well-adapted to the dynamic environmental conditions of sulfidic gas vents.
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Affiliation(s)
- Sushmita Patwardhan
- Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ 08901, USA
| | - Jonathan Phan
- Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, NJ 08901, USA
| | - Francesco Smedile
- Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ 08901, USA
| | - Costantino Vetriani
- Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ 08901, USA
- Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, NJ 08901, USA
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7
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Wang H, Mulgaonkar N, Mallawarachchi S, Ramasamy M, Padilla CS, Irigoyen S, Coaker G, Mandadi KK, Fernando S. Evaluation of Candidatus Liberibacter Asiaticus Efflux Pump Inhibition by Antimicrobial Peptides. Molecules 2022; 27:molecules27248729. [PMID: 36557860 PMCID: PMC9782701 DOI: 10.3390/molecules27248729] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 11/17/2022] [Accepted: 11/18/2022] [Indexed: 12/14/2022] Open
Abstract
Citrus greening, also known as Huanglongbing (HLB), is caused by the unculturable bacterium Candidatus Liberibacter spp. (e.g., CLas), and has caused a devastating decline in citrus production in many areas of the world. As of yet, there are no definitive treatments for controlling the disease. Antimicrobial peptides (AMPs) that have the potential to block secretion-dependent effector proteins at the outer-membrane domains were screened in silico. Predictions of drug-receptor interactions were built using multiple in silico techniques, including molecular docking analysis, molecular dynamics, molecular mechanics generalized Born surface area analysis, and principal component analysis. The efflux pump TolC of the Type 1 secretion system interacted with natural bacteriocin plantaricin JLA-9, blocking the β barrel. The trajectory-based principal component analysis revealed the possible binding mechanism of the peptides. Furthermore, in vitro assays using two closely related culturable surrogates of CLas (Liberibacter crescens and Rhizobium spp.) showed that Plantaricin JLA-9 and two other screened AMPs inhibited bacterial growth and caused mortality. The findings contribute to designing effective therapies to manage plant diseases associated with Candidatus Liberibacter spp.
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Affiliation(s)
- Haoqi Wang
- Biological and Agricultural Engineering Department, Texas A&M University, College Station, TX 77843, USA
| | - Nirmitee Mulgaonkar
- Biological and Agricultural Engineering Department, Texas A&M University, College Station, TX 77843, USA
| | - Samavath Mallawarachchi
- Biological and Agricultural Engineering Department, Texas A&M University, College Station, TX 77843, USA
| | - Manikandan Ramasamy
- Texas A&M AgriLife Research & Extension Center, Texas A&M University System, 2415 E. Highway 83, Weslaco, TX 78596, USA
| | - Carmen S. Padilla
- Texas A&M AgriLife Research & Extension Center, Texas A&M University System, 2415 E. Highway 83, Weslaco, TX 78596, USA
| | - Sonia Irigoyen
- Texas A&M AgriLife Research & Extension Center, Texas A&M University System, 2415 E. Highway 83, Weslaco, TX 78596, USA
| | - Gitta Coaker
- Department of Plant Pathology, University of California, Davis, CA 95616, USA
| | - Kranthi K. Mandadi
- Texas A&M AgriLife Research & Extension Center, Texas A&M University System, 2415 E. Highway 83, Weslaco, TX 78596, USA
- Department of Plant Pathology and Microbiology, Texas A&M University System, 2132 TAMU, College Station, TX 77843, USA
- Institute for Advancing Health through Agriculture, Texas A&M AgriLife, College Station, TX 77843, USA
- Correspondence: (K.K.M.); (S.F.)
| | - Sandun Fernando
- Biological and Agricultural Engineering Department, Texas A&M University, College Station, TX 77843, USA
- Correspondence: (K.K.M.); (S.F.)
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8
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Garcia L, Molina MC, Padgett-Pagliai KA, Torres PS, Bruna RE, García Véscovi E, González CF, Gadea J, Marano MR. A serralysin-like protein of Candidatus Liberibacter asiaticus modulates components of the bacterial extracellular matrix. Front Microbiol 2022; 13:1006962. [DOI: 10.3389/fmicb.2022.1006962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 09/26/2022] [Indexed: 11/13/2022] Open
Abstract
Huanglongbing (HLB), the current major threat for Citrus species, is caused by intracellular alphaproteobacteria of the genus Candidatus Liberibacter (CaL), with CaL asiaticus (CLas) being the most prevalent species. This bacterium inhabits phloem cells and is transmitted by the psyllid Diaphorina citri. A gene encoding a putative serralysin-like metalloprotease (CLIBASIA_01345) was identified in the CLas genome. The expression levels of this gene were found to be higher in citrus leaves than in psyllids, suggesting a function for this protease in adaptation to the plant environment. Here, we study the putative role of CLas-serralysin (Las1345) as virulence factor. We first assayed whether Las1345 could be secreted by two different surrogate bacteria, Rhizobium leguminosarum bv. viciae A34 (A34) and Serratia marcescens. The protein was detected only in the cellular fraction of A34 and S. marcescens expressing Las1345, and increased protease activity of those bacteria by 2.55 and 4.25-fold, respectively. In contrast, Las1345 expressed in Nicotiana benthamiana leaves did not show protease activity nor alterations in the cell membrane, suggesting that Las1345 do not function as a protease in the plant cell. Las1345 expression negatively regulated cell motility, exopolysaccharide production, and biofilm formation in Xanthomonas campestris pv. campestris (Xcc). This bacterial phenotype was correlated with reduced growth and survival on leaf surfaces as well as reduced disease symptoms in N. benthamiana and Arabidopsis. These results support a model where Las1345 could modify extracellular components to adapt bacterial shape and appendages to the phloem environment, thus contributing to virulence.
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9
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Huang Y, Zhu F, Koh J, Stanton D, Chen S, Wang N. Proteomic and bioinformatic analyses of proteins in the outer membrane and extracellular compartments and outer membrane vesicles of Candidatus Liberibacter species. Front Microbiol 2022; 13:977710. [PMID: 36225379 PMCID: PMC9548881 DOI: 10.3389/fmicb.2022.977710] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Accepted: 09/02/2022] [Indexed: 11/23/2022] Open
Abstract
Citrus Huanglongbing (HLB) is the most devastating citrus disease in the world. Candidatus Liberibacter asiaticus (Las) is the prevalent HLB pathogen, which is yet to be cultivated. A recent study demonstrates that Las does not contain pathogenicity factors that are directly responsible for HLB symptoms. Instead, Las triggers systemic and chronic immune responses, representing a pathogen-triggered immune disease. Importantly, overproduction of reactive oxygen species (ROS) causes systemic cell death of phloem tissues, thus causing HLB symptoms. Because Las resides in the phloem tissues, it is expected that phloem cell might recognize outer membrane proteins, outer membrane vesicle (OMV) proteins and extracellular proteins of Las to contribute to the immune responses. Because Las has not been cultivated, we used Liberibacter crescens (Lcr) as a surrogate to identify proteins in the OM fraction, OMV proteins and extracellular proteins by liquid chromatography with tandem mass spectrometry (LC–MS/MS). We observed OMVs of Lcr under scanning electron microscope, representing the first experimental evidence that Liberibacter can deliver proteins to the extracellular compartment. In addition, we also further analyzed LC–MS/MS data using bioinformatic tools. Our study provides valuable information regarding the biology of Ca. Liberibacter species and identifies many putative proteins that may interact with host proteins in the phloem tissues.
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Affiliation(s)
- Yixiao Huang
- Department of Plant Pathology, Citrus Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL, United States
| | - Fanchao Zhu
- Proteomics and Mass Spectrometry, Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, FL, United States
| | - Jin Koh
- Proteomics and Mass Spectrometry, Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, FL, United States
| | - Daniel Stanton
- Department of Plant Pathology, Citrus Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL, United States
| | - Sixue Chen
- Proteomics and Mass Spectrometry, Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, FL, United States
| | - Nian Wang
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL, United States
- *Correspondence: Nian Wang,
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10
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Silva Gonçalves O, Bonandi Barreiros R, Martins Tupy S, Ferreira Santana M. A reverse-ecology framework to uncover the potential metabolic interplay among 'Candidatus Liberibacter' species, Citrus hosts and psyllid vector. Gene X 2022; 837:146679. [PMID: 35752379 DOI: 10.1016/j.gene.2022.146679] [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: 04/10/2022] [Revised: 05/31/2022] [Accepted: 06/10/2022] [Indexed: 11/04/2022] Open
Abstract
'Candidatus Liberibacter' species have developed a dependency on essential nutrients and metabolites from the host cell, as a result of substantial genome reduction. Still, it is difficult to state which nutrients they acquire and whether or not they are metabolically reliant. We used a reverse-ecology model to investigate the potential metabolic interactions of 'Ca Liberibacter' species, Citrus, and the psyllid Diaphorina citri in the huanglongbing disease pyramid. Our findings show that hosts (citrus and psyllid) tend to support the nutritional needs of 'Ca. Liberibacter' species, implying that the pathogen's metabolism has become tightly linked to hosts, which may reflect in the parasite lifestyle of this important genus.
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Affiliation(s)
- Osiel Silva Gonçalves
- Grupo de Genômica Evolutiva Microbiana, Laboratório de Genética Molecular de Microrganismos, Departamento de Microbiologia, Instituto de Biotecnologia Aplicada à Agropecuária, Universidade Federal de Viçosa, Minas Gerais, Brazil
| | - Ralph Bonandi Barreiros
- Departmento de Fitotecnia, Laboratório de Biotecnologia de Plantas Horticulas, Escola Superior de Agricultura "Luiz de Queiroz", Universidade de São Paulo, Brazil
| | - Sumaya Martins Tupy
- Grupo de Genômica Evolutiva Microbiana, Laboratório de Genética Molecular de Microrganismos, Departamento de Microbiologia, Instituto de Biotecnologia Aplicada à Agropecuária, Universidade Federal de Viçosa, Minas Gerais, Brazil
| | - Mateus Ferreira Santana
- Grupo de Genômica Evolutiva Microbiana, Laboratório de Genética Molecular de Microrganismos, Departamento de Microbiologia, Instituto de Biotecnologia Aplicada à Agropecuária, Universidade Federal de Viçosa, Minas Gerais, Brazil.
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11
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Cai L, Jain M, Munoz-Bodnar A, Huguet-Tapia JC, Gabriel DW. A synthetic 'essentialome' for axenic culturing of 'Candidatus Liberibacter asiaticus'. BMC Res Notes 2022; 15:125. [PMID: 35365194 PMCID: PMC8973516 DOI: 10.1186/s13104-022-05986-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Accepted: 02/23/2022] [Indexed: 11/10/2022] Open
Abstract
OBJECTIVE 'Candidatus Liberibacter asiaticus' (CLas) is associated with the devastating citrus 'greening' disease. All attempts to achieve axenic growth and complete Koch's postulates with CLas have failed to date, at best yielding complex cocultures with very low CLas titers detectable only by PCR. Reductive genome evolution has rendered all pathogenic 'Ca. Liberibacter' spp. deficient in multiple key biosynthetic, metabolic and structural pathways that are highly unlikely to be rescued in vitro by media supplementation alone. By contrast, Liberibacter crescens (Lcr) is axenically cultured and its genome is both syntenic and highly similar to CLas. Our objective is to achieve replicative axenic growth of CLas via addition of missing culturability-related Lcr genes. RESULTS Bioinformatic analyses identified 405 unique ORFs in Lcr but missing (or truncated) in all 24 sequenced CLas strains. Site-directed mutagenesis confirmed and extended published EZ-Tn5 mutagenesis data, allowing elimination of 310 of these 405 genes as nonessential, leaving 95 experimentally validated Lcr genes as essential for CLas growth in axenic culture. Experimental conditions for conjugation of large GFP-expressing plasmids from Escherichia coli to Lcr were successfully established for the first time, providing a practical method for transfer of large groups of 'essential' Lcr genes to CLas.
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Affiliation(s)
- Lulu Cai
- Department of Plant Pathology, University of Florida, Gainesville, FL, 32611, USA
| | - Mukesh Jain
- Department of Plant Pathology, University of Florida, Gainesville, FL, 32611, USA
| | | | - Jose C Huguet-Tapia
- Department of Plant Pathology, University of Florida, Gainesville, FL, 32611, USA
| | - Dean W Gabriel
- Department of Plant Pathology, University of Florida, Gainesville, FL, 32611, USA.
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Jain M, Cai L, Black I, Azadi P, Carlson RW, Jones KM, Gabriel DW. ' Candidatus Liberibacter asiaticus'-Encoded BCP Peroxiredoxin Suppresses Lipopolysaccharide-Mediated Defense Signaling and Nitrosative Stress In Planta. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2022; 35:257-273. [PMID: 34931906 DOI: 10.1094/mpmi-09-21-0230-r] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The lipopolysaccharides (LPS) of gram-negative bacteria trigger a nitrosative and oxidative burst in both animals and plants during pathogen invasion. Liberibacter crescens strain BT-1 is a surrogate for functional genomic studies of the uncultured pathogenic 'Candidatus Liberibacter' spp. that are associated with severe diseases such as citrus greening and potato zebra chip. Structural determination of L. crescens LPS revealed the presence of a very long chain fatty acid modification. L. crescens LPS pretreatment suppressed growth of Xanthomonas perforans on nonhost tobacco (Nicotiana benthamiana) and X. citri subsp. citri on host orange (Citrus sinensis), confirming bioactivity of L. crescens LPS in activation of systemic acquired resistance (SAR). L. crescens LPS elicited a rapid burst of nitric oxide (NO) in suspension cultured tobacco cells. Pharmacological inhibitor assays confirmed that arginine-utilizing NO synthase (NOS) activity was the primary source of NO generation elicited by L. crescens LPS. LPS treatment also resulted in biological markers of NO-mediated SAR activation, including an increase in the glutathione pool, callose deposition, and activation of the salicylic acid and azelaic acid (AzA) signaling networks. Transient expression of 'Ca. L. asiaticus' bacterioferritin comigratory protein (BCP) peroxiredoxin in tobacco compromised AzA signaling, a prerequisite for LPS-triggered SAR. Western blot analyses revealed that 'Ca. L. asiaticus' BCP peroxiredoxin prevented peroxynitrite-mediated tyrosine nitration in tobacco. 'Ca. L. asiaticus' BCP peroxiredoxin (i) attenuates NO-mediated SAR signaling and (ii) scavenges peroxynitrite radicals, which would facilitate repetitive cycles of 'Ca. L. asiaticus' acquisition and transmission by fecund psyllids throughout the limited flush period in citrus.[Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
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Affiliation(s)
- Mukesh Jain
- Plant Pathology Department, University of Florida, Gainesville, FL 32611, U.S.A
| | - Lulu Cai
- Plant Pathology Department, University of Florida, Gainesville, FL 32611, U.S.A
| | - Ian Black
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, U.S.A
| | - Parastoo Azadi
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, U.S.A
| | - Russell W Carlson
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, U.S.A
| | - Kathryn M Jones
- Department of Biological Science, Florida State University, Tallahassee, FL 32306, U.S.A
| | - Dean W Gabriel
- Plant Pathology Department, University of Florida, Gainesville, FL 32611, U.S.A
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Merfa MV, Naranjo E, Shantharaj D, De La Fuente L. Growth of ' Candidatus Liberibacter asiaticus' in Commercial Grapefruit Juice-Based Media Formulations Reveals Common Cell Density-Dependent Transient Behaviors. PHYTOPATHOLOGY 2022; 112:131-144. [PMID: 34340531 DOI: 10.1094/phyto-06-21-0228-fi] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The phloem-restricted, insect-transmitted bacterium 'Candidatus Liberibacter asiaticus' (CLas) is associated with huanglongbing (HLB), the most devastating disease of citrus worldwide. The inability to culture CLas impairs the understanding of its virulence mechanisms and the development of effective management strategies to control this incurable disease. Previously, our research group used commercial grapefruit juice (GJ) to prolong the viability of CLas in vitro. In the present study, GJ was amended with a wide range of compounds and incubated under different conditions to optimize CLas growth. Remarkably, results showed that CLas growth ratios were inversely proportional to the initial inoculum concentration. This correlation is probably regulated by a cell density-dependent mechanism, because diluting samples between subcultures allowed CLas to resume growth. Moreover, strategies to reduce the cell density of CLas, such as subculturing at short intervals and incubating samples under flow conditions, allowed this bacterium to multiply and reach maximum growth as early as 3 days after inoculation, although no sustained exponential growth was observed under any tested condition. Unfortunately, cultures were only transient, because CLas lost viability over time; nevertheless, we obtained populations of about 105 genome equivalents/ml repeatedly. Finally, we established an ex vivo system to grow CLas within periwinkle calli that could be used to propagate bacterial inoculum in the lab. In this study we determined the influence of a comprehensive set of conditions and compounds on CLas growth in culture. We hope our results will help guide future efforts toward the long-sought goal of culturing CLas axenically.
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Affiliation(s)
- Marcus V Merfa
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL 36849
| | - Eber Naranjo
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL 36849
| | - Deepak Shantharaj
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL 36849
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Black IM, Heiss C, Jain M, Muszyński A, Carlson RW, Gabriel DW, Azadi P. Structure of Lipopolysaccharide from Liberibacter crescens Is Low Molecular Weight and Offers Insight into Candidatus Liberibacter Biology. Int J Mol Sci 2021; 22:11240. [PMID: 34681907 PMCID: PMC8537588 DOI: 10.3390/ijms222011240] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Revised: 10/06/2021] [Accepted: 10/07/2021] [Indexed: 11/30/2022] Open
Abstract
Huanglongbing (HLB) disease, also known as citrus greening disease, was first reported in the US in 2005. Since then, the disease has decimated the citrus industry in Florida, resulting in billions of dollars in crop losses and the destruction of thousands of acres of citrus groves. The causative agent of citrus greening disease is the phloem limited pathogen Candidatus Liberibacter asiaticus. As it has not been cultured, very little is known about the structural biology of the organism. Liberibacter are part of the Rhizobiaceae family, which includes nitrogen-fixing symbionts of legumes as well as the Agrobacterium plant pathogens. To better understand the Liberibacter genus, a closely related culturable bacterium (Liberibacter crescens or Lcr) has attracted attention as a model organism for structural and functional genomics of Liberibacters. Given that the structure of lipopolysaccharides (LPS) from Gram-negative bacteria plays a crucial role in mediating host-pathogen interactions, we sought to characterize the LPS from Lcr. We found that the major lipid A component of the LPS consisted of a pentaacylated molecule with a β-6-GlcN disaccharide backbone lacking phosphate. The polysaccharide portion of the LPS was unusual compared to previously described members of the Rhizobiaceae family in that it contained ribofuranosyl residues. The LPS structure presented here allows us to extrapolate known LPS structure/function relationships to members of the Liberibacter genus which cannot yet be cultured. It also offers insights into the biology of the organism and how they manage to effectively attack citrus trees.
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Affiliation(s)
- Ian M. Black
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA; (I.M.B.); (C.H.); (A.M.); (R.W.C.)
| | - Christian Heiss
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA; (I.M.B.); (C.H.); (A.M.); (R.W.C.)
| | - Mukesh Jain
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611, USA; (M.J.); (D.W.G.)
| | - Artur Muszyński
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA; (I.M.B.); (C.H.); (A.M.); (R.W.C.)
| | - Russell W. Carlson
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA; (I.M.B.); (C.H.); (A.M.); (R.W.C.)
| | - Dean W. Gabriel
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611, USA; (M.J.); (D.W.G.)
| | - Parastoo Azadi
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA; (I.M.B.); (C.H.); (A.M.); (R.W.C.)
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Cai L, Jain M, Sena-Vélez M, Jones KM, Fleites LA, Heck M, Gabriel DW. Tad pilus-mediated twitching motility is essential for DNA uptake and survival of Liberibacters. PLoS One 2021; 16:e0258583. [PMID: 34644346 PMCID: PMC8513845 DOI: 10.1371/journal.pone.0258583] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Accepted: 10/01/2021] [Indexed: 12/12/2022] Open
Abstract
Axenically cultured Liberibacter crescens (Lcr) is a closely related surrogate for uncultured plant pathogenic species of the genus Liberibacter, including ‘Candidatus L. asiaticus’ (CLas) and ‘Ca. L. solanacearum’ (CLso). All Liberibacters encode a completely conserved gene repertoire for both flagella and Tad (Tight Adherence) pili and all are missing genes critical for nucleotide biosynthesis. Both flagellar swimming and Tad pilus-mediated twitching motility in Lcr were demonstrated for the first time. A role for Tad pili in the uptake of extracellular dsDNA for food in Liberibacters was suspected because both twitching and DNA uptake are impossible without repetitive pilus extension and retraction, and no genes encoding other pilus assemblages or mechanisms for DNA uptake were predicted to be even partially present in any of the 35 fully sequenced Liberibacter genomes. Insertional mutations of the Lcr Tad pilus genes cpaA, cpaB, cpaE, cpaF and tadC all displayed such severely reduced growth and viability that none could be complemented. A mutation affecting cpaF (motor ATPase) was further characterized and the strain displayed concomitant loss of twitching, viability and reduced periplasmic uptake of extracellular dsDNA. Mutations of comEC, encoding the inner membrane competence channel, had no effect on either motility or growth but completely abolished natural transformation in Lcr. The comEC mutation was restored by complementation using comEC from Lcr but not from CLas strain psy62 or CLso strain RS100, indicating that unlike Lcr, these pathogens were not naturally competent for transformation. This report provides the first evidence that the Liberibacter Tad pili are dynamic and essential for both motility and DNA uptake, thus extending their role beyond surface adherence.
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Affiliation(s)
- Lulu Cai
- Plant Pathology Department, University of Florida, Gainesville, Florida, United States of America
| | - Mukesh Jain
- Plant Pathology Department, University of Florida, Gainesville, Florida, United States of America
| | - Marta Sena-Vélez
- Department of Biological Science, Florida State University, Tallahassee, Florida, United States of America
| | - Kathryn M. Jones
- Department of Biological Science, Florida State University, Tallahassee, Florida, United States of America
| | - Laura A. Fleites
- USDA Agricultural Research Service, Robert W. Holley Center for Agriculture and Health, Ithaca, New York, United States of America
| | - Michelle Heck
- USDA Agricultural Research Service, Robert W. Holley Center for Agriculture and Health, Ithaca, New York, United States of America
| | - Dean W. Gabriel
- Plant Pathology Department, University of Florida, Gainesville, Florida, United States of America
- * E-mail:
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16
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Pan L, Gardner CL, Beliakoff R, da Silva D, Zuo R, Pagliai FA, Padgett-Pagliai KA, Merli ML, Bahadiroglu E, Gonzalez CF, Lorca GL. PrbP modulates biofilm formation in Liberibacter crescens. Environ Microbiol 2021; 23:7121-7138. [PMID: 34431209 DOI: 10.1111/1462-2920.15740] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 08/17/2021] [Accepted: 08/22/2021] [Indexed: 12/31/2022]
Abstract
In Liberibacter asiaticus, PrbP is a transcriptional regulatory protein involved in survival and persistence during host infection. Tolfenamic acid was previously found to inhibit interactions between PrbP and the promotor region of rplK, resulting in reduced survival of L. asiaticus in the citrus host. In this study, we performed transcriptome analyses to elucidate the PrbP regulon in L. crescens, as it is phylogenetically the closest related species to L. asiaticus that can be grown in laboratory conditions. Chemical inhibition of PrbP with tolfenamic acid revealed that PrbP is involved in the regulation of diverse cellular processes, including stress response, cell motility, cell cycle and biofilm formation. In vitro DNA binding and bacterial two-hybrid assays also suggested that PrbP is a global regulator of multiple transcription factors (RpoH, VisN, PleD, MucR, MocR and CtrA) at both transcriptional and/or post-transcriptional levels. Sub-lethal concentrations of tolfenamic acid significantly reduced the attachment of L. crescens during biofilm formation and decreased long-term persistence in biofilm structures. Overall, our findings show the importance of PrbP in regulating diverse biological processes through direct and indirect interactions with other transcriptional regulators in L. crescens.
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Affiliation(s)
- Lei Pan
- Microbiology and Cell Science Department, Genetics Institute, Institute of Food and Agricultural Science, University of Florida, Gainesville, FL, USA
| | - Christopher L Gardner
- Microbiology and Cell Science Department, Genetics Institute, Institute of Food and Agricultural Science, University of Florida, Gainesville, FL, USA
| | - Reagan Beliakoff
- Microbiology and Cell Science Department, Genetics Institute, Institute of Food and Agricultural Science, University of Florida, Gainesville, FL, USA
| | - Danilo da Silva
- Microbiology and Cell Science Department, Genetics Institute, Institute of Food and Agricultural Science, University of Florida, Gainesville, FL, USA
| | - Ran Zuo
- Microbiology and Cell Science Department, Genetics Institute, Institute of Food and Agricultural Science, University of Florida, Gainesville, FL, USA
| | - Fernando A Pagliai
- Microbiology and Cell Science Department, Genetics Institute, Institute of Food and Agricultural Science, University of Florida, Gainesville, FL, USA
| | - Kaylie A Padgett-Pagliai
- Microbiology and Cell Science Department, Genetics Institute, Institute of Food and Agricultural Science, University of Florida, Gainesville, FL, USA
| | - Marcelo L Merli
- Microbiology and Cell Science Department, Genetics Institute, Institute of Food and Agricultural Science, University of Florida, Gainesville, FL, USA
| | - Erol Bahadiroglu
- Microbiology and Cell Science Department, Genetics Institute, Institute of Food and Agricultural Science, University of Florida, Gainesville, FL, USA
| | - Claudio F Gonzalez
- Microbiology and Cell Science Department, Genetics Institute, Institute of Food and Agricultural Science, University of Florida, Gainesville, FL, USA
| | - Graciela L Lorca
- Microbiology and Cell Science Department, Genetics Institute, Institute of Food and Agricultural Science, University of Florida, Gainesville, FL, USA
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17
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Alquézar B, Carmona L, Bennici S, Peña L. Engineering of citrus to obtain huanglongbing resistance. Curr Opin Biotechnol 2021; 70:196-203. [PMID: 34198205 DOI: 10.1016/j.copbio.2021.06.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 06/04/2021] [Accepted: 06/07/2021] [Indexed: 12/23/2022]
Abstract
Huanglongbing (HLB) disease is threatening the sustainability of citriculture in affected regions because of its rapid spread and the severity of the symptoms it induces. Herein, we summarise the main research findings that can be exploited to develop HLB-resistant cultivars. A major bottleneck has been the lack of a system for the ex vivo cultivation of HLB-associated bacteria (CLs) in true plant hosts, which precludes the evaluation of target genes/metabolites in reliable plant/pathogen/vector environments. With regard to HLB vectors, several biotechnologies which have been proven in laboratory settings to be effective for insect control are presented. Finally, new genotypes that are resistant to CLs or their insect vectors are described, and the most relevant strategies for fighting HLB are highlighted.
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Affiliation(s)
- Berta Alquézar
- Laboratório de Biotecnologia Vegetal, Pesquisa & Desenvolvimento, Fundo de Defesa da Citricultura (Fundecitrus), Vila Melhado, 14807-040 Araraquara, São Paulo, Brazil; Instituto de Biología Molecular y Celular de Plantas (IBMCP), Consejo Superior de Investigaciones Científicas (CSIC)-Universidad Politécnica de Valencia (UPV), 46022 Valencia, Spain
| | - Lourdes Carmona
- Instituto de Biología Molecular y Celular de Plantas (IBMCP), Consejo Superior de Investigaciones Científicas (CSIC)-Universidad Politécnica de Valencia (UPV), 46022 Valencia, Spain
| | - Stefania Bennici
- Instituto de Biología Molecular y Celular de Plantas (IBMCP), Consejo Superior de Investigaciones Científicas (CSIC)-Universidad Politécnica de Valencia (UPV), 46022 Valencia, Spain
| | - Leandro Peña
- Laboratório de Biotecnologia Vegetal, Pesquisa & Desenvolvimento, Fundo de Defesa da Citricultura (Fundecitrus), Vila Melhado, 14807-040 Araraquara, São Paulo, Brazil; Instituto de Biología Molecular y Celular de Plantas (IBMCP), Consejo Superior de Investigaciones Científicas (CSIC)-Universidad Politécnica de Valencia (UPV), 46022 Valencia, Spain.
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Zhang Z, Han Q, Mao X, Liu J, Wang W, Li D, Zhou F, Ke Y, Xu L, Hu L. Discovery of novel SecA inhibitors against "Candidatus Liberibacter asiaticus" through virtual screening and biological evaluation. Chem Biol Drug Des 2021; 98:395-404. [PMID: 33963664 DOI: 10.1111/cbdd.13859] [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: 09/24/2020] [Revised: 02/07/2021] [Accepted: 03/14/2021] [Indexed: 11/26/2022]
Abstract
"Candidatus Liberibacter asiaticus" (Ca. L. asiaticus) is the causal agent of Huanglongbing disease of citrus and current study focuses on the discovery of novel small-molecule inhibitors against SecA protein of Ca. L. asiaticus. In this study, homologous modeling was used to construct the three-dimensional structure of SecA. Then, molecular docking-based virtual screening and two rounds of in vitro bacteriostatic experiments were utilized to identify novel small-molecule inhibitors of SecA. Encouragingly, 93 compounds were obtained and two of them (P684-2850, P684-3808) showed strong antimicrobial activities against Liberibacter crescens BT-1 in bacteriostatic experiments. Finally, molecular dynamics simulations were employed to explore the binding modes of the receptor-ligand complexes. Results in MD simulations showed that compound P684-3808 was relatively stable during simulation, while compound P684-2850 left the binding pocket. Compound P684-3808 might be suitable as a lead compound for further development of antimicrobial compounds against SecA of Ca. L. asiaticus.
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Affiliation(s)
- Zhengfang Zhang
- Zhejiang Yangshengtang Institute of Natural Medication Co., Ltd, Hangzhou, China
| | - Quan Han
- Zhejiang Yangshengtang Institute of Natural Medication Co., Ltd, Hangzhou, China
| | - Xiongxing Mao
- Zhejiang Yangshengtang Institute of Natural Medication Co., Ltd, Hangzhou, China
| | - Jinhua Liu
- Zhejiang Yangshengtang Institute of Natural Medication Co., Ltd, Hangzhou, China
| | - Wei Wang
- Zhejiang Yangshengtang Institute of Natural Medication Co., Ltd, Hangzhou, China
| | - Dong Li
- Zhejiang Yangshengtang Institute of Natural Medication Co., Ltd, Hangzhou, China
| | - Feng Zhou
- Zhejiang Yangshengtang Institute of Natural Medication Co., Ltd, Hangzhou, China
| | - Yang Ke
- Zhejiang Provincial Key Laboratory of Biometrology and Inspection & Quarantine, College of Life Sciences, China Jiliang University, Hangzhou, China
| | - Lei Xu
- Institute of Bioinformatics and Medical Engineering, Jiangsu University of Technology, Changzhou, China
| | - Liu Hu
- Zhejiang Yangshengtang Institute of Natural Medication Co., Ltd, Hangzhou, China
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Irigoyen S, Ramasamy M, Pant S, Niraula P, Bedre R, Gurung M, Rossi D, Laughlin C, Gorman Z, Achor D, Levy A, Kolomiets MV, Sétamou M, Badillo-Vargas IE, Avila CA, Irey MS, Mandadi KK. Plant hairy roots enable high throughput identification of antimicrobials against Candidatus Liberibacter spp. Nat Commun 2020; 11:5802. [PMID: 33199718 PMCID: PMC7669877 DOI: 10.1038/s41467-020-19631-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Accepted: 10/26/2020] [Indexed: 12/20/2022] Open
Abstract
A major bottleneck in identifying therapies to control citrus greening and other devastating plant diseases caused by fastidious pathogens is our inability to culture the pathogens in defined media or axenic cultures. As such, conventional approaches for antimicrobial evaluation (genetic or chemical) rely on time-consuming, low-throughput and inherently variable whole-plant assays. Here, we report that plant hairy roots support the growth of fastidious pathogens like Candidatus Liberibacter spp., the presumptive causal agents of citrus greening, potato zebra chip and tomato vein greening diseases. Importantly, we leverage the microbial hairy roots for rapid, reproducible efficacy screening of multiple therapies. We identify six antimicrobial peptides, two plant immune regulators and eight chemicals which inhibit Candidatus Liberibacter spp. in plant tissues. The antimicrobials, either singly or in combination, can be used as near- and long-term therapies to control citrus greening, potato zebra chip and tomato vein greening diseases.
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Affiliation(s)
- Sonia Irigoyen
- Texas A&M AgriLife Research and Extension Center, Weslaco, TX, USA
| | | | - Shankar Pant
- Texas A&M AgriLife Research and Extension Center, Weslaco, TX, USA
- Agricultural Research Service, US Department of Agriculture, Stillwater, OK, USA
| | - Prakash Niraula
- Texas A&M AgriLife Research and Extension Center, Weslaco, TX, USA
| | - Renesh Bedre
- Texas A&M AgriLife Research and Extension Center, Weslaco, TX, USA
| | - Meena Gurung
- Texas A&M AgriLife Research and Extension Center, Weslaco, TX, USA
| | - Denise Rossi
- Texas A&M AgriLife Research and Extension Center, Weslaco, TX, USA
| | - Corinne Laughlin
- Texas A&M AgriLife Research and Extension Center, Weslaco, TX, USA
| | - Zachary Gorman
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX, USA
| | - Diann Achor
- Citrus Research and Education Center, University of Florida, Lake Alfred, FL, USA
| | - Amit Levy
- Citrus Research and Education Center, University of Florida, Lake Alfred, FL, USA
- Department of Plant Pathology, University of Florida, Gainesville, FL, USA
| | - Michael V Kolomiets
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX, USA
| | - Mamoudou Sétamou
- Texas A&M University-Kingsville, Citrus Center, Weslaco, TX, USA
| | - Ismael E Badillo-Vargas
- Texas A&M AgriLife Research and Extension Center, Weslaco, TX, USA
- Department of Entomology, Texas A&M University, College Station, TX, USA
| | - Carlos A Avila
- Texas A&M AgriLife Research and Extension Center, Weslaco, TX, USA
- Department of Horticultural Sciences, Texas A&M University, College Station, TX, USA
| | | | - Kranthi K Mandadi
- Texas A&M AgriLife Research and Extension Center, Weslaco, TX, USA.
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX, USA.
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Naranjo E, Merfa MV, Santra S, Ozcan A, Johnson E, Cobine PA, De La Fuente L. Zinkicide Is a ZnO-Based Nanoformulation with Bactericidal Activity against Liberibacter crescens in Batch Cultures and in Microfluidic Chambers Simulating Plant Vascular Systems. Appl Environ Microbiol 2020; 86:e00788-20. [PMID: 32561578 PMCID: PMC7414956 DOI: 10.1128/aem.00788-20] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 06/12/2020] [Indexed: 01/09/2023] Open
Abstract
Phloem-limited bacterial "Candidatus Liberibacter" species are associated with incurable plant diseases worldwide. Antimicrobial treatments for these pathogens are challenging due to the difficulty of reaching the vascular tissue they occupy at bactericidal concentrations. Here, in vitro antimicrobial mechanisms of Zinkicide TMN110 (ZnK), a nonphytotoxic zinc oxide (ZnO)-based nanoformulation, were compared to those of bulk ZnO (b-ZnO) using as a model the only culturable species of the genus, Liberibacter crescens Minimum bactericidal concentration (MBC) determination and time-kill assays showed that ZnK has a bactericidal effect against L. crescens, whereas b-ZnO is bacteriostatic. When ZnK was used at the MBC (150 ppm), its antimicrobial mechanisms included an increase in Zn solubility, generation of intracellular reactive oxygen species, lipid peroxidation, and cell membrane disruption; all of these were of greater intensity than those of b-ZnO. Inhibition of biofilms, which are important during insect vector colonization, was stronger by ZnK than by b-ZnO at concentrations between 2.5 and 10 ppm in batch cultures; however, neither ZnK nor b-ZnO removed L. crescens preformed biofilms when applied between 100 and 400 ppm. In microfluidic chambers simulating source-to-sink phloem movement, ZnK significantly outperformed b-ZnO in Zn mobilization and bactericidal activity against L. crescens planktonic cells in sink reservoirs. In microfluidic chamber assays assessing antibiofilm activity, ZnK displayed a significantly enhanced bactericidal activity against L. crescens individual attached cells as well as preformed biofilms compared to that of b-ZnO. The superior mobility and antimicrobial activity of ZnK in microenvironments make this formulation a promising product to control plant diseases caused by "Candidatus Liberibacter" species and other plant vascular pathogens.IMPORTANCE "Candidatus Liberibacter" species are associated with incurable plant diseases that have caused billions of dollars of losses for United States and world agriculture. Chemical control of these pathogens is complicated, because their life cycle combines intracellular vascular stages in plant hosts with transmission by highly mobile insect vectors. To date, "Candidatus Liberibacter" species are mostly unculturable, except for Liberibacter crescens, a member of the genus that has been used as a model for in vitro assays. Here, we evaluated the potential of Zinkicide (ZnK) as an antimicrobial against "Candidatus Liberibacter" species in batch cultures and under flow conditions, using L. crescens as a biological model. ZnK displayed bactericidal activity against L. crescens in batch cultures and showed increased mobility and bactericidal activity in microfluidic devices resembling "Candidatus Liberibacter" species natural habitats. ZnK performance observed here against L. crescens makes this compound a promising candidate to control plant diseases caused by vascular pathogens.
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Affiliation(s)
- Eber Naranjo
- Department of Entomology and Plant Pathology, Auburn University, Auburn, Alabama, USA
| | - Marcus V Merfa
- Department of Entomology and Plant Pathology, Auburn University, Auburn, Alabama, USA
| | - Swadeshmukul Santra
- NanoScience Technology Center, University of Central Florida, Orlando, Florida, USA
- Department of Chemistry, University of Central Florida, Orlando, Florida, USA
- Department of Materials Science and Engineering, University of Central Florida, Orlando, Florida, USA
- Burnett School of Biomedical Sciences, University of Central Florida, Orlando, Florida, USA
| | - Ali Ozcan
- NanoScience Technology Center, University of Central Florida, Orlando, Florida, USA
- Department of Chemistry, University of Central Florida, Orlando, Florida, USA
- Vocational School of Technical Sciences, Karamanoglu Mehmetbey University, Karaman, Turkey
| | - Evan Johnson
- Citrus Research and Education Center, University of Florida, Lake Alfred, Florida, USA
| | - Paul A Cobine
- Department of Biological Sciences, Auburn University, Auburn, Alabama, USA
| | - Leonardo De La Fuente
- Department of Entomology and Plant Pathology, Auburn University, Auburn, Alabama, USA
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21
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Brandenburg CA, Castro CA, Blacutt AA, Costa EA, Brinton KC, Corral DW, Drozd CL, Roper MC, Rolshausen PE, Maloney KN, Lockner JW. Synthesis of Deoxyradicinin, an Inhibitor of Xylella fastidiosa and Liberibacter crescens, a Culturable Surrogate for Candidatus Liberibacter asiaticus. JOURNAL OF NATURAL PRODUCTS 2020; 83:1810-1816. [PMID: 32510948 DOI: 10.1021/acs.jnatprod.9b01207] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Pierce's disease of grapevine and citrus huanglongbing are caused by the bacterial pathogens Xylella fastidiosa and Candidatus Liberibacter asiaticus (CLas), respectively. Both pathogens reside within the plant vascular system, occluding water and nutrient transport, leading to a decrease in productivity and fruit marketability and ultimately death of their hosts. Field observations of apparently healthy plants in disease-affected vineyards and groves led to the hypothesis that natural products from endophytes may inhibit these bacterial pathogens. Previously, we showed that the natural product radicinin from Cochliobolus sp. inhibits X. fastidiosa. Herein we describe a chemical synthesis of deoxyradicinin and establish it as an inhibitor of both X. fastidiosa and Liberibacter crescens, a culturable surrogate for CLas. The key to this three-step route is a zinc-mediated enolate C-acylation, which allows for direct introduction of the propenyl side chain without extraneous redox manipulations.
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Affiliation(s)
- Connor A Brandenburg
- Department of Chemistry, Point Loma Nazarene University, San Diego, California 92106, United States
| | - Claudia A Castro
- Department of Microbiology and Plant Pathology, University of California, Riverside, California 92521, United States
| | - Alex A Blacutt
- Department of Microbiology and Plant Pathology, University of California, Riverside, California 92521, United States
| | | | - Kyler C Brinton
- Department of Chemistry, Point Loma Nazarene University, San Diego, California 92106, United States
| | - Diana W Corral
- Department of Chemistry, Point Loma Nazarene University, San Diego, California 92106, United States
| | - Christopher L Drozd
- Department of Microbiology and Plant Pathology, University of California, Riverside, California 92521, United States
| | - M Caroline Roper
- Department of Microbiology and Plant Pathology, University of California, Riverside, California 92521, United States
| | - Philippe E Rolshausen
- Department of Botany and Plant Sciences, University of California, Riverside, California 92521, United States
| | - Katherine N Maloney
- Department of Chemistry, Point Loma Nazarene University, San Diego, California 92106, United States
| | - Jonathan W Lockner
- Department of Chemistry, Point Loma Nazarene University, San Diego, California 92106, United States
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22
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Thapa SP, De Francesco A, Trinh J, Gurung FB, Pang Z, Vidalakis G, Wang N, Ancona V, Ma W, Coaker G. Genome-wide analyses of Liberibacter species provides insights into evolution, phylogenetic relationships, and virulence factors. MOLECULAR PLANT PATHOLOGY 2020; 21:716-731. [PMID: 32108417 PMCID: PMC7170780 DOI: 10.1111/mpp.12925] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 01/27/2020] [Accepted: 01/28/2020] [Indexed: 05/04/2023]
Abstract
'Candidatus Liberibacter' species are insect-transmitted, phloem-limited α-Proteobacteria in the order of Rhizobiales. The citrus industry is facing significant challenges due to huanglongbing, associated with infection from 'Candidatus Liberibacter asiaticus' (Las). In order to gain greater insight into 'Ca. Liberibacter' biology and genetic diversity, we have performed genome sequencing and comparative analyses of diverse 'Ca. Liberibacter' species, including those that can infect citrus. Our phylogenetic analysis differentiates 'Ca. Liberibacter' species and Rhizobiales in separate clades and suggests stepwise evolution from a common ancestor splitting first into nonpathogenic Liberibacter crescens followed by diversification of pathogenic 'Ca. Liberibacter' species. Further analysis of Las genomes from different geographical locations revealed diversity among isolates from the United States. Our phylogenetic study also indicates multiple Las introduction events in California and spread of the pathogen from Florida to Texas. Texan Las isolates were closely related, while Florida and Asian isolates exhibited the most genetic variation. We have identified conserved Sec translocon (SEC)-dependent effectors likely involved in bacterial survival and virulence of Las and analysed their expression in their plant host (citrus) and insect vector (Diaphorina citri). Individual SEC-dependent effectors exhibited differential expression patterns between host and vector, indicating that Las uses its effector repertoire to differentially modulate diverse organisms. Collectively, this work provides insights into the evolution of 'Ca. Liberibacter' species, the introduction of Las in the United States and identifies promising Las targets for disease management.
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Affiliation(s)
- Shree P. Thapa
- Department of Plant PathologyUniversity of CaliforniaDavisCAUSA
| | - Agustina De Francesco
- Department of Microbiology and Plant PathologyUniversity of CaliforniaRiversideCAUSA
| | - Jessica Trinh
- Department of Microbiology and Plant PathologyUniversity of CaliforniaRiversideCAUSA
| | - Fatta B. Gurung
- Citrus CenterDepartment of Agriculture, Agribusiness and Environmental SciencesTexas A&M University‐KingsvilleWeslacoTXUSA
| | - Zhiqian Pang
- Citrus Research and Education CenterDepartment of Microbiology and Cell ScienceUniversity of FloridaLake AlfredFLUSA
| | - Georgios Vidalakis
- Department of Microbiology and Plant PathologyUniversity of CaliforniaRiversideCAUSA
| | - Nian Wang
- Citrus Research and Education CenterDepartment of Microbiology and Cell ScienceUniversity of FloridaLake AlfredFLUSA
| | - Veronica Ancona
- Citrus CenterDepartment of Agriculture, Agribusiness and Environmental SciencesTexas A&M University‐KingsvilleWeslacoTXUSA
| | - Wenbo Ma
- Department of Microbiology and Plant PathologyUniversity of CaliforniaRiversideCAUSA
| | - Gitta Coaker
- Department of Plant PathologyUniversity of CaliforniaDavisCAUSA
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23
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Growth Dynamics and Survival of Liberibacter crescens BT-1, an Important Model Organism for the Citrus Huanglongbing Pathogen " Candidatus Liberibacter asiaticus". Appl Environ Microbiol 2019; 85:AEM.01656-19. [PMID: 31420343 PMCID: PMC6803310 DOI: 10.1128/aem.01656-19] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Accepted: 08/12/2019] [Indexed: 11/20/2022] Open
Abstract
Liberibacter crescens is a bacterium that is closely related to plant pathogens that have caused billions of dollars in crop losses in recent years. Particularly devastating are citrus losses due to citrus greening disease, also known as Huanglongbing, which is caused by “Candidatus Liberibacter asiaticus” and carried by the Asian citrus psyllid. L. crescens is the only close relative of “Ca. Liberibacter asiaticus” that can currently be grown in culture, and it therefore serves as an important model organism for the growth, genetic manipulation, and biological control of the pathogenic species. Here, we show that one of the greatest limitations to L. crescens growth is the sharp increase in alkaline conditions it produces as a consequence of consumption of its preferred nutrient source. In addition to new information about L. crescens growth and metabolism, we provide new guidelines for culture conditions that improve the survival and yield of L. crescens. Liberibacter crescens is the only cultured member of its genus, which includes the devastating plant pathogen “Candidatus Liberibacter asiaticus,” associated with citrus greening/Huanglongbing (HLB). L. crescens has a larger genome and greater metabolic flexibility than “Ca. Liberibacter asiaticus” and the other uncultured plant-pathogenic Liberibacter species, and it is currently the best model organism available for these pathogens. L. crescens grows slowly and dies rapidly under current culture protocols and this extreme fastidiousness makes it challenging to study. We have determined that a major cause of rapid death of L. crescens in batch culture is its alkalinization of the medium (to pH 8.5 by the end of logarithmic phase). The majority of this alkalinization is due to consumption of alpha-ketoglutaric acid as its primary carbon source, with a smaller proportion of the pH rise due to NH3 production. Controlling the pH rise with higher buffering capacity and lower starting pH improved recoverability of cells from 10-day cultures by >1,000-fold. We have also performed a detailed analysis of L. crescens growth with total cell numbers calibrated to the optical density and the percentage of live and recoverable bacteria determined over 10-day time courses. We modified L. crescens culture conditions to greatly enhance survival and increase maximum culture density. The similarities between L. crescens and the pathogenic liberibacters make this work relevant to efforts to culture the latter organisms. Our results also suggest that growth-dependent pH alteration that overcomes medium buffering should always be considered when growing fastidious bacteria. IMPORTANCELiberibacter crescens is a bacterium that is closely related to plant pathogens that have caused billions of dollars in crop losses in recent years. Particularly devastating are citrus losses due to citrus greening disease, also known as Huanglongbing, which is caused by “Candidatus Liberibacter asiaticus” and carried by the Asian citrus psyllid. L. crescens is the only close relative of “Ca. Liberibacter asiaticus” that can currently be grown in culture, and it therefore serves as an important model organism for the growth, genetic manipulation, and biological control of the pathogenic species. Here, we show that one of the greatest limitations to L. crescens growth is the sharp increase in alkaline conditions it produces as a consequence of consumption of its preferred nutrient source. In addition to new information about L. crescens growth and metabolism, we provide new guidelines for culture conditions that improve the survival and yield of L. crescens.
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24
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A high-throughput system to identify inhibitors of Candidatus Liberibacter asiaticus transcription regulators. Proc Natl Acad Sci U S A 2019; 116:18009-18014. [PMID: 31427509 DOI: 10.1073/pnas.1905149116] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Citrus greening disease, also known as huanglongbing (HLB), is the most devastating disease of Citrus worldwide. This incurable disease is caused primarily by the bacterium Candidatus Liberibacter asiaticus and spread by feeding of the Asian Citrus Psyllid, Diaphorina citri Ca L. asiaticus cannot be cultured; its growth is restricted to citrus phloem and the psyllid insect. Management of infected trees includes use of broad-spectrum antibiotics, which have disadvantages. Recent work has sought to identify small molecules that inhibit Ca L. asiaticus transcription regulators, based on a premise that at least some regulators control expression of genes necessary for virulence. We describe a synthetic, high-throughput screening system to identify compounds that inhibit activity of Ca L. asiaticus transcription activators LdtR, RpoH, and VisNR. Our system uses the closely related model bacterium, Sinorhizobium meliloti, as a heterologous host for expression of a Ca L. asiaticus transcription activator, the activity of which is detected through expression of an enhanced green fluorescent protein (EGFP) gene fused to a target promoter. We used this system to screen more than 120,000 compounds for compounds that inhibited regulator activity, but not growth. Our screen identified several dozen compounds that inhibit regulator activity in our assay. This work shows that, in addition to providing a means of characterizing Ca L. asiaticus regulators, an S. meliloti host can be used for preliminary identification of candidate inhibitory molecules.
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