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Lestiyani A, Joko T, Holford P, Charles Beattie GA, Donovan N, Mo J, Subandiyah S, Iwanami T. Natural Infection of Murraya paniculata and Murraya sumatrana with ' Candidatus Liberibacter asiaticus' in Java. PLANT DISEASE 2024:PDIS12232593RE. [PMID: 38657079 DOI: 10.1094/pdis-12-23-2593-re] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
The phloem-limited bacterium 'Candidatus Liberibacter asiaticus' (CLas) is the putative causal pathogen of the severe Asiatic form of huanglongbing (citrus greening) and is most commonly transmitted by the Asiatic citrus psyllid Diaphorina citri. CLas severely affects many Citrus species and hybrids and has been recorded in the Citrus relative, orange jasmine, Murraya paniculata (L.) Jack (syn. M. exotica L.). In this study, 13 accessions of three Murraya species (M. paniculata, M. sumatrana Roxb., and M. lucida [G.Forst.] Mabb.) and the Papuan form of a putative hybrid (M. omphalocarpa Hayata) were identified morphologically and molecularly based on sequence identity of the matK-5'trnK region of the chloroplast genome, and infection on these plants under field conditions was determined by PCR and quantitative real-time PCR (qPCR) on two to four occasions over 14 months. CLas was repeatedly detected in leaflet midribs by PCR and qPCR on four and three accessions of M. paniculata and M. sumatrana, respectively. It was not detected in leaflet midribs of single accessions of M. lucida and M. omphalocarpa. The species identification of the CLas-positive accessions was further confirmed using all the molecular taxonomic markers consisting of the six fragments of the maternally inherited chloroplast genome and part of the nuclear-encoded internal transcribed spacer (ITS) region. The results indicated that natural infection of M. paniculata and M. sumatrana with CLas can occur in Java. To our knowledge, this is the first demonstration of the natural infection of M. sumatrana with CLas. Further studies are required to determine whether infections persist in the absence of D. citri.
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Affiliation(s)
- Ayu Lestiyani
- Study Program of Biotechnology, Graduate School, Universitas Gadjah Mada, Barek, Yogyakarta 55281, Indonesia
- Study Program of Agrotechnology, Faculty of Agriculture, Universitas Tidar, Magelang, Central Java 56116, Indonesia
| | - Tri Joko
- Department of Plant Protection, Faculty of Agriculture, Universitas Gadjah Mada, Yogyakarta 55281, Indonesia
| | - Paul Holford
- School of Science, Western Sydney University, Penrith 2751, Australia
| | | | | | - Jianhua Mo
- NSW Department of Primary Industries, Orange, Australia
| | - Siti Subandiyah
- Department of Plant Protection, Faculty of Agriculture, Universitas Gadjah Mada, Yogyakarta 55281, Indonesia
| | - Toru Iwanami
- Department of Agriculture, Faculty of Agriculture, Tokyo University of Agriculture, Atsugi, Kanagawa 243-0034, Japan
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Ghosh D, Kokane S, Savita BK, Kumar P, Sharma AK, Ozcan A, Kokane A, Santra S. Huanglongbing Pandemic: Current Challenges and Emerging Management Strategies. PLANTS (BASEL, SWITZERLAND) 2022; 12:plants12010160. [PMID: 36616289 PMCID: PMC9824665 DOI: 10.3390/plants12010160] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 12/06/2022] [Accepted: 12/07/2022] [Indexed: 05/09/2023]
Abstract
Huanglongbing (HLB, aka citrus greening), one of the most devastating diseases of citrus, has wreaked havoc on the global citrus industry in recent decades. The culprit behind such a gloomy scenario is the phloem-limited bacteria "Candidatus Liberibacter asiaticus" (CLas), which are transmitted via psyllid. To date, there are no effective long-termcommercialized control measures for HLB, making it increasingly difficult to prevent the disease spread. To combat HLB effectively, introduction of multipronged management strategies towards controlling CLas population within the phloem system is deemed necessary. This article presents a comprehensive review of up-to-date scientific information about HLB, including currently available management practices and unprecedented challenges associated with the disease control. Additionally, a triangular disease management approach has been introduced targeting pathogen, host, and vector. Pathogen-targeting approaches include (i) inhibition of important proteins of CLas, (ii) use of the most efficient antimicrobial or immunity-inducing compounds to suppress the growth of CLas, and (iii) use of tools to suppress or kill the CLas. Approaches for targeting the host include (i) improvement of the host immune system, (ii) effective use of transgenic variety to build the host's resistance against CLas, and (iii) induction of systemic acquired resistance. Strategies for targeting the vector include (i) chemical and biological control and (ii) eradication of HLB-affected trees. Finally, a hypothetical model for integrated disease management has been discussed to mitigate the HLB pandemic.
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Affiliation(s)
- Dilip Ghosh
- Plant Virology Laboratory, ICAR-Central Citrus Research Institute, Nagpur 440033, India
- Correspondence: (D.G.); (A.K.S.); (S.S.)
| | - Sunil Kokane
- Plant Virology Laboratory, ICAR-Central Citrus Research Institute, Nagpur 440033, India
| | - Brajesh Kumar Savita
- Department of Biosciences and Bioengineering, Indian Institute of Technology Roorkee, Roorkee 247667, India
| | - Pranav Kumar
- Department of Biosciences and Bioengineering, Indian Institute of Technology Roorkee, Roorkee 247667, India
| | - Ashwani Kumar Sharma
- Department of Biosciences and Bioengineering, Indian Institute of Technology Roorkee, Roorkee 247667, India
- Correspondence: (D.G.); (A.K.S.); (S.S.)
| | - Ali Ozcan
- Vocational School of Technical Sciences, Karamanoglu Mehmetbey University, 70200 Karaman, Turkey
- Scientific and Technological Studies Application and Research Center, Karamanoglu Mehmetbey University, 70200 Karaman, Turkey
| | - Amol Kokane
- Plant Virology Laboratory, ICAR-Central Citrus Research Institute, Nagpur 440033, India
| | - Swadeshmukul Santra
- Departments of Chemistry, Nano Science Technology Center, and Burnett School of Biomedical Sciences, University of Central Florida, Orlando, FL 32816, USA
- Correspondence: (D.G.); (A.K.S.); (S.S.)
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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: 4] [Impact Index Per Article: 2.0] [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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Srivastava AK, Das AK, Jagannadham PTK, Bora P, Ansari FA, Bhate R. Bioprospecting Microbiome for Soil and Plant Health Management Amidst Huanglongbing Threat in Citrus: A Review. FRONTIERS IN PLANT SCIENCE 2022; 13:858842. [PMID: 35557712 PMCID: PMC9088001 DOI: 10.3389/fpls.2022.858842] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Accepted: 03/21/2022] [Indexed: 06/15/2023]
Abstract
Microorganisms have dynamic and complex interactions with their hosts. Diverse microbial communities residing near, on, and within the plants, called phytobiome, are an essential part of plant health and productivity. Exploiting citrus-associated microbiomes represents a scientific approach toward sustained and environment-friendly module of citrus production, though periodically exposed to several threats, with Huanglongbing (HLB) predominantly being most influential. Exploring the composition and function of the citrus microbiome, and possible microbial redesigning under HLB disease pressure has sparked renewed interest in recent times. A concise account of various achievements in understanding the citrus-associated microbiome, in various niche environments viz., rhizosphere, phyllosphere, endosphere, and core microbiota alongside their functional attributes has been thoroughly reviewed and presented. Efforts were also made to analyze the actual role of the citrus microbiome in soil fertility and resilience, interaction with and suppression of invading pathogens along with native microbial communities and their consequences thereupon. Despite the desired potential of the citrus microbiota to counter different pathogenic diseases, utilizing the citrus microbiome for beneficial applications at the field level is yet to be translated as a commercial product. We anticipate that advancement in multiomics technologies, high-throughput sequencing and culturing, genome editing tools, artificial intelligence, and microbial consortia will provide some exciting avenues for citrus microbiome research and microbial manipulation to improve the health and productivity of citrus plants.
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Affiliation(s)
- Anoop Kumar Srivastava
- Indian Council of Agricultural Research (ICAR)-Central Citrus Research Institute, Nagpur, India
| | - Ashis Kumar Das
- Indian Council of Agricultural Research (ICAR)-Central Citrus Research Institute, Nagpur, India
| | | | - Popy Bora
- Department of Plant Pathology, Assam Agricultural University, Jorhat, India
| | - Firoz Ahmad Ansari
- Indian Council of Agricultural Research (ICAR)-Central Citrus Research Institute, Nagpur, India
| | - Ruchi Bhate
- Indian Council of Agricultural Research (ICAR)-Central Citrus Research Institute, Nagpur, India
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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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Yang C, Ancona V. An Overview of the Mechanisms Against " Candidatus Liberibacter asiaticus": Virulence Targets, Citrus Defenses, and Microbiome. Front Microbiol 2022; 13:850588. [PMID: 35391740 PMCID: PMC8982080 DOI: 10.3389/fmicb.2022.850588] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Accepted: 02/18/2022] [Indexed: 12/01/2022] Open
Abstract
Citrus Huanglongbing (HLB) or citrus greening, is the most destructive disease for citrus worldwide. It is caused by the psyllid-transmitted, phloem-limited bacteria "Candidatus Liberibacter asiaticus" (CLas). To date, there are still no effective practical strategies for curing citrus HLB. Understanding the mechanisms against CLas can contribute to the development of effective approaches for combatting HLB. However, the unculturable nature of CLas has hindered elucidating mechanisms against CLas. In this review, we summarize the main aspects that contribute to the understanding about the mechanisms against CLas, including (1) CLas virulence targets, focusing on inhibition of virulence genes; (2) activation of citrus host defense genes and metabolites of HLB-tolerant citrus triggered by CLas, and by agents; and (3) we also review the role of citrus microbiome in combatting CLas. Finally, we discuss novel strategies to continue studying mechanisms against CLas and the relationship of above aspects.
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Affiliation(s)
- Chuanyu Yang
- Department of Agriculture, Agribusiness, and Environmental Sciences, Citrus Center, Texas A&M University-Kingsville, Weslaco, TX, United States
| | - Veronica Ancona
- Department of Agriculture, Agribusiness, and Environmental Sciences, Citrus Center, Texas A&M University-Kingsville, Weslaco, TX, United States
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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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Padgett-Pagliai KA, Pagliai FA, da Silva DR, Gardner CL, Lorca GL, Gonzalez CF. Osmotic stress induces long-term biofilm survival in Liberibacter crescens. BMC Microbiol 2022; 22:52. [PMID: 35148684 PMCID: PMC8832773 DOI: 10.1186/s12866-022-02453-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Accepted: 01/21/2022] [Indexed: 11/24/2022] Open
Abstract
Citrus greening, also known as Huanglongbing (HLB), is a devastating citrus plant disease caused predominantly by Liberibacter asiaticus. While nearly all Liberibacter species remain uncultured, here we used the culturable L. crescens BT-1 as a model to examine physiological changes in response to the variable osmotic conditions and nutrient availability encountered within the citrus host. Similarly, physiological responses to changes in growth temperature and dimethyl sulfoxide concentrations were also examined, due to their use in many of the currently employed therapies to control the spread of HLB. Sublethal heat stress was found to induce the expression of genes related to tryptophan biosynthesis, while repressing the expression of ribosomal proteins. Osmotic stress induces expression of transcriptional regulators involved in expression of extracellular structures, while repressing the biosynthesis of fatty acids and aromatic amino acids. The effects of osmotic stress were further evaluated by quantifying biofilm formation of L. crescens in presence of increasing sucrose concentrations at different stages of biofilm formation, where sucrose-induced osmotic stress delayed initial cell attachment while enhancing long-term biofilm viability. Our findings revealed that exposure to osmotic stress is a significant contributing factor to the long term survival of L. crescens and, possibly, to the pathogenicity of other Liberibacter species.
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Affiliation(s)
- Kaylie A Padgett-Pagliai
- Department of Microbiology and Cell Science, Genetics Institute, Institute of Food and Agricultural Sciences, University of Florida, 2033 Mowry Road, PO Box 103610, Gainesville, FL, 32610-3610, USA
| | - Fernando A Pagliai
- Department of Microbiology and Cell Science, Genetics Institute, Institute of Food and Agricultural Sciences, University of Florida, 2033 Mowry Road, PO Box 103610, Gainesville, FL, 32610-3610, USA
| | - Danilo R da Silva
- Department of Microbiology and Cell Science, Genetics Institute, Institute of Food and Agricultural Sciences, University of Florida, 2033 Mowry Road, PO Box 103610, Gainesville, FL, 32610-3610, USA
| | - Christopher L Gardner
- Department of Microbiology and Cell Science, Genetics Institute, Institute of Food and Agricultural Sciences, University of Florida, 2033 Mowry Road, PO Box 103610, Gainesville, FL, 32610-3610, USA
| | - Graciela L Lorca
- Department of Microbiology and Cell Science, Genetics Institute, Institute of Food and Agricultural Sciences, University of Florida, 2033 Mowry Road, PO Box 103610, Gainesville, FL, 32610-3610, USA
| | - Claudio F Gonzalez
- Department of Microbiology and Cell Science, Genetics Institute, Institute of Food and Agricultural Sciences, University of Florida, 2033 Mowry Road, PO Box 103610, Gainesville, FL, 32610-3610, USA.
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Killiny N. Made for Each Other: Vector-Pathogen Interfaces in the Huanglongbing Pathosystem. PHYTOPATHOLOGY 2022; 112:26-43. [PMID: 34096774 DOI: 10.1094/phyto-05-21-0182-fi] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Citrus greening, or huanglongbing (HLB), currently is the most destructive disease of citrus. HLB disease is putatively caused by the phloem-restricted α-proteobacterium 'Candidatus Liberibacter asiaticus'. This bacterium is transmitted primarily by the Asian citrus psyllid Diaphorina citri (Hemiptera: Liviidae). Most animal pathogens are considered pathogenic to their insect vectors, whereas the relationships between plant pathogens and their insect vectors are variable. Lately, the relationship of 'Ca. L. asiaticus' with its insect vector, D. citri, has been well investigated at the molecular, biochemical, and biological levels in many studies. Herein, the findings concerning this relationship are discussed and molecular features of the acquisition of 'Ca. L. asiaticus' from the plant host and its growth and circulation within D. citri, as well as its transmission to plants, are presented. In addition, the effects of 'Ca. L. asiaticus' on the energy metabolism (respiration, tricarboxylic acid cycle, and adenosine triphosphate production), metabolic pathways, immune system, endosymbionts, and detoxification enzymes of D. citri are discussed together with other impacts such as shorter lifespan, altered feeding behavior, and higher fecundity. Overall, although 'Ca. L. asiaticus' has significant negative effects on its insect vector, it increases its vector fitness, indicating that it develops a mutualistic relationship with its vector. This review will help in understanding the specific interactions between 'Ca. L. asiaticus' and its psyllid vector in order to design innovative management strategies.
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Affiliation(s)
- Nabil Killiny
- Citrus Research and Education Center, IFAS, University of Florida, Lake Alfred, FL 33850
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10
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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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Hu B, Rao MJ, Deng X, Pandey SS, Hendrich C, Ding F, Wang N, Xu Q. Molecular signatures between citrus and Candidatus Liberibacter asiaticus. PLoS Pathog 2021; 17:e1010071. [PMID: 34882744 PMCID: PMC8659345 DOI: 10.1371/journal.ppat.1010071] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Citrus Huanglongbing (HLB), also known as citrus greening, is one of the most devastating citrus diseases worldwide. Candidatus Liberibacter asiaticus (CLas) is the most prevalent strain associated with HLB, which is yet to be cultured in vitro. None of the commercial citrus cultivars are resistant to HLB. The pathosystem of Ca. Liberibacter is complex and remains a mystery. In this review, we focus on the recent progress in genomic research on the pathogen, the interaction of host and CLas, and the influence of CLas infection on the transcripts, proteins, and metabolism of the host. We have also focused on the identification of candidate genes for CLas pathogenicity or the improvements of HLB tolerance in citrus. In the end, we propose potentially promising areas for mechanistic studies of CLas pathogenicity, defense regulators, and genetic improvement for HLB tolerance/resistance in the future.
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Affiliation(s)
- Bin Hu
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Ministry of Agriculture), Huazhong Agricultural University, Wuhan, Hubei, China
| | - Muhammad Junaid Rao
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Ministry of Agriculture), Huazhong Agricultural University, Wuhan, Hubei, China
| | - Xiuxin Deng
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Ministry of Agriculture), Huazhong Agricultural University, Wuhan, Hubei, China
| | - Sheo Shankar Pandey
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, Florida, United States of America
| | - Connor Hendrich
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, Florida, United States of America
| | - Fang Ding
- Hubei Key Laboratory of Plant Pathology, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Nian Wang
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, Florida, United States of America
| | - Qiang Xu
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Ministry of Agriculture), Huazhong Agricultural University, Wuhan, Hubei, China
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12
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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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13
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Vasconcelos FNC, Li J, Pang Z, Vincent C, Wang N. The Total Population Size of ' Candidatus Liberibacter asiaticus' Inside the Phloem of Citrus Trees and the Corresponding Metabolic Burden Related to Huanglongbing Disease Development. PHYTOPATHOLOGY 2021; 111:1122-1128. [PMID: 33090080 DOI: 10.1094/phyto-09-20-0388-r] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
'Candidatus Liberibacter asiaticus' (CLas) is the predominant causal agent of citrus huanglongbing, the most devastating citrus disease worldwide. CLas colonizes phloem tissue and causes phloem dysfunction. The pathogen population size in local tissues and in the whole plant is critical for the development of disease symptoms by determining the load of pathogenicity factors and metabolic burden to the host. However, the total population size of CLas in a whole plant and the ratio of CLas to citrus cells in local tissues have not been addressed previously. The total CLas population size for 2.5-year-old 'Valencia' sweet orange on 'Kuharske' citrange rootstock trees was quantified using quantitative PCR to be approximately 1.74 × 109 cells/tree, whereas 7- and 20-year-old sweet orange trees were estimated to be 4.3 × 1010 cells/tree, and 6.0 × 1010 cells/tree, respectively. The majority of CLas cells were distributed in leaf tissues (55.58%), followed by those in branch (36.78%), feeder root (4.75%), trunk (2.39%), and structural root (0.51%) tissues. The ratios of citrus cells to CLas cells for branch, leaf, trunk, feeder root, and structural root samples were within approximately 39 to 79, 44 to 124, 153 to 1,355, 191 to 1,054, and 561 to 3,760, respectively, representing the metabolic burden of CLas in different organs. It was estimated that the ratios of phloem cells to CLas cells for branch, leaf, trunk, feeder root, and structural root samples are approximately 0.39 to 0.79, 0.44 to 1.24, 1.53 to 13.55, 1.91 to 10.54, and 5.61 to 37.60, respectively. Approximately 0.01% of the total citrus phloem volume was estimated to be occupied by CLas, explaining the difficulty to observe CLas in most tissues under transmission electron microscopy. The CLas titer inside the leaf was estimated to be approximately 1.64 × 106 cells/leaf or 9.2 × 104 cells cm-2 in leaves, approximately 104 times less than that of typical apoplastic bacterial pathogens. This study provides quantitative estimates of phloem colonization by bacterial pathogens and furthers the understanding of the biology and virulence mechanisms of CLas.
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Affiliation(s)
- Fernanda N C Vasconcelos
- Citrus Research and Education Center (CREC), Department of Microbiology and Cell Science, University of Florida, Lake Alfred, FL 33850
| | - Jinuyn Li
- Citrus Research and Education Center (CREC), Department of Microbiology and Cell Science, University of Florida, Lake Alfred, FL 33850
| | - Zhiqian Pang
- Citrus Research and Education Center (CREC), Department of Microbiology and Cell Science, University of Florida, Lake Alfred, FL 33850
| | - Christopher Vincent
- Citrus Research and Education Center (CREC), Department of Horticultural Sciences, University of Florida, Lake Alfred, FL 33850
| | - Nian Wang
- Citrus Research and Education Center (CREC), Department of Microbiology and Cell Science, University of Florida, Lake Alfred, FL 33850
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14
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Metagenomic Analysis Reveals the Mechanism for the Observed Increase in Antibacterial Activity of Penicillin against Uncultured Bacteria Candidatus Liberibacter asiaticus Relative to Oxytetracycline in Planta. Antibiotics (Basel) 2020; 9:antibiotics9120874. [PMID: 33291469 PMCID: PMC7768456 DOI: 10.3390/antibiotics9120874] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 11/23/2020] [Accepted: 12/03/2020] [Indexed: 11/16/2022] Open
Abstract
Citrus huanglongbing (HLB) is a devastating disease for the citrus industry. The previous studies demonstrated that oxytetracycline and penicillin are effective antibiotics against Candidatus Liberibacter asiaticus (CLas). However, since CLas is uncultured, the mechanisms of action of antibiotics against CLas are still unclear. It was recently reported that the endophytic microbial communities are associated with the progression of citrus HLB after oxytetracycline and penicillin treatment. Therefore, we hypothesize that penicillin has greater antibacterial activity against CLas than oxytetracycline, which may be associated with the alteration of the structure and function of endophytic microbial communities in HLB-affected citrus in response to these antibiotics. To test this hypothesis, the microbiome of HLB-affected citrus leaves treated with these two antibiotics was analyzed using a metagenomic method. Our results indicate that the microbial structure and function in HLB-affected citrus were altered by these two antibiotics. The relative abundance of beneficial bacterial species, including Streptomyces avermitilis and Bradyrhizobium, was higher in penicillin-treated plants compared to those treated with oxytetracycline, and the relative abundance of the bacterial species (such as Propionibacterium acnes and Synechocystis sp PCC 6803) associated with CLas survival was lower for penicillin-treated plants compared to oxytetracycline-treated plants. These results indicate that penicillin has greater antibacterial activity against CLas. Based on the metagenomic analysis, this study elucidated the mechanism for the observed increase in antibacterial activity of penicillin against CLas. The data presented here are not only invaluable for developing eco-friendly and effective biocontrol strategies to combat citrus HLB, but also provide a method for revealing mechanism of antimicrobial against uncultured bacteria in host.
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15
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Inoue H, Yamashita-Muraki S, Fujiwara K, Honda K, Ono H, Nonaka T, Kato Y, Matsuyama T, Sugano S, Suzuki M, Masaoka Y. Fe 2+ Ions Alleviate the Symptom of Citrus Greening Disease. Int J Mol Sci 2020; 21:E4033. [PMID: 32512918 PMCID: PMC7312295 DOI: 10.3390/ijms21114033] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 05/30/2020] [Accepted: 06/02/2020] [Indexed: 11/17/2022] Open
Abstract
Citrus greening (CG) is among the most devastating citrus diseases worldwide. CG-infected trees exhibit interveinal chlorotic leaves due to iron (Fe) deficiency derived from CG; thus, Fe content is lower in infected leaves than in healthy leaves. In this study, we demonstrated that the foliar application of Fe2+ relieves the symptom of CG infection in citrus trees. We applied Fe2+ and citrate to the leaves of infected rough lemon plants. Following this treatment, a reduction in the number of yellow symptomatic leaves was observed, and their growth was restored. Using chlorophyll content as an index, we screened for effective Fe complexes and found that a high ratio of citrate to Fe2+ in the applied solution led to effects against CG in Shikuwasa trees. A high proportion of Fe2+ to total Fe was another key factor explaining the effectiveness of the solution in CG infection, indicating the importance of Fe2+ absorption into plant cells. We confirmed the proportion of Fe2+ to total Fe through the high correlation of reflectometry data via a triazine reaction and X-ray absorption fine structure analysis. These results demonstrate that the foliar application of a high-Fe2+ citrate solution can restore the growth of CG diseased trees.
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Affiliation(s)
- Haruhiko Inoue
- Plant Function Research Unit, Division of Plant and Microbial Sciences, National Agriculture and Food Research Organization (NARO), Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8605, Japan; (H.I.); (S.S.)
| | - Sakiko Yamashita-Muraki
- Graduate School of Biosphere Science, Hiroshima University, Higashi-Hiroshima 739-8528, Japan; (S.Y.-M.); (K.F.); (K.H.); (H.O.)
| | - Kanako Fujiwara
- Graduate School of Biosphere Science, Hiroshima University, Higashi-Hiroshima 739-8528, Japan; (S.Y.-M.); (K.F.); (K.H.); (H.O.)
| | - Kayoko Honda
- Graduate School of Biosphere Science, Hiroshima University, Higashi-Hiroshima 739-8528, Japan; (S.Y.-M.); (K.F.); (K.H.); (H.O.)
| | - Hiroki Ono
- Graduate School of Biosphere Science, Hiroshima University, Higashi-Hiroshima 739-8528, Japan; (S.Y.-M.); (K.F.); (K.H.); (H.O.)
| | - Takamasa Nonaka
- Toyota Central R&D Labs., Inc., Yokomichi, Nagakute, Aichi 480-1192, Japan; (T.N.); (Y.K.)
| | - Yuichi Kato
- Toyota Central R&D Labs., Inc., Yokomichi, Nagakute, Aichi 480-1192, Japan; (T.N.); (Y.K.)
| | - Tomoya Matsuyama
- Environment and Energy Innovation Department, Frontier Research and Development Division, Aichi Steel Corporation, Wanowari, Arao-machi, Tokai, Aichi 476-8666, Japan;
| | - Shoji Sugano
- Plant Function Research Unit, Division of Plant and Microbial Sciences, National Agriculture and Food Research Organization (NARO), Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8605, Japan; (H.I.); (S.S.)
| | - Motofumi Suzuki
- Environment and Energy Innovation Department, Frontier Research and Development Division, Aichi Steel Corporation, Wanowari, Arao-machi, Tokai, Aichi 476-8666, Japan;
| | - Yoshikuni Masaoka
- Graduate School of Biosphere Science, Hiroshima University, Higashi-Hiroshima 739-8528, Japan; (S.Y.-M.); (K.F.); (K.H.); (H.O.)
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16
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Attaran E, Berim A, Killiny N, Beyenal H, Gang DR, Omsland A. Controlled replication of 'Candidatus Liberibacter asiaticus' DNA in citrus leaf discs. Microb Biotechnol 2020; 13:747-759. [PMID: 31958876 PMCID: PMC7111093 DOI: 10.1111/1751-7915.13531] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 12/10/2019] [Accepted: 12/14/2019] [Indexed: 12/13/2022] Open
Abstract
'Candidatus Liberibacter asiaticus' is a fastidious bacterium and a putative agent of citrus greening disease (a.k.a., huanglongbing, HLB), a significant agricultural disease that affects citrus fruit quality and tree health. In citrus, 'Ca. L. asiaticus' is phloem limited. Lack of culture tools to study 'Ca. L. asiaticus' complicates analysis of this important organism. To improve understanding of 'Ca. L. asiaticus'-host interactions including parameters that affect 'Ca. L. asiaticus' replication, methods suitable for screening pathogen responses to physicochemical and nutritional variables are needed. We describe a leaf disc-based culture assay that allows highly selective measurement of changes in 'Ca. L. asiaticus' DNA within plant tissue incubated under specific physicochemical and nutritional conditions. qPCR analysis targeting the hypothetical gene CD16-00155 (strain A4) allowed selective quantification of 'Ca. L. asiaticus' DNA content within infected tissue. 'Ca. L. asiaticus' DNA replication was observed in response to glucose exclusively under microaerobic conditions, and the antibiotic amikacin further enhanced 'Ca. L. asiaticus' DNA replication. Metabolite profiling revealed a moderate impact of 'Ca. L. asiaticus' on the ability of leaf tissue to metabolize and respond to glucose.
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Affiliation(s)
- Elham Attaran
- Paul G. Allen School for Global Animal HealthWashington State UniversityPullmanWAUSA
| | - Anna Berim
- Institute of Biological ChemistryWashington State UniversityPullmanWAUSA
| | - Nabil Killiny
- Plant Pathology DepartmentCitrus Research and Education CenterUniversity of FloridaLake AlfredFLUSA
| | - Haluk Beyenal
- Gene and Linda Voiland School of Chemical Engineering and BioengineeringWashington State UniversityPullmanWAUSA
| | - David R. Gang
- Institute of Biological ChemistryWashington State UniversityPullmanWAUSA
| | - Anders Omsland
- Paul G. Allen School for Global Animal HealthWashington State UniversityPullmanWAUSA
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17
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Padhi EMT, Maharaj N, Lin SY, Mishchuk DO, Chin E, Godfrey K, Foster E, Polek M, Leveau JHJ, Slupsky CM. Metabolome and Microbiome Signatures in the Roots of Citrus Affected by Huanglongbing. PHYTOPATHOLOGY 2019; 109:2022-2032. [PMID: 31433274 DOI: 10.1094/phyto-03-19-0103-r] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Huanglongbing (HLB) is a severe, incurable citrus disease caused by the bacterium 'Candidatus Liberibacter asiaticus' (CLas). Although citrus leaves serve as the site of initial infection, CLas is known to migrate to and colonize the root system; however, little is known about the impact of CLas infection on root metabolism and resident microbial communities. Scions of 'Lisbon' lemon and 'Washington Navel' orange grafted onto 'Carrizo' rootstock were grafted with either CLas-infected citrus budwood or uninfected budwood. Roots were obtained from trees 46 weeks after grafting and analyzed via 1H nuclear magnetic resonance spectroscopy to identify water-soluble root metabolites and high-throughput sequencing of 16S rRNA and ITS gene amplicons to determine the relative abundance of bacterial and fungal taxa in the root rhizosphere and endosphere. In both citrus varieties, 27 metabolites were identified, of which several were significantly different between CLas(+) and control plants. CLas infection also appeared to alter the microbial community structure near and inside the roots of citrus plants. Nonmetric multidimensional scaling (NMDS) and a principal coordinate analysis (PCoA) revealed distinct metabolite and microbial profiles, demonstrating that CLas impacts the root metabolome and microbiome in a manner that is variety-specific.
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Affiliation(s)
- Emily M T Padhi
- Department of Food Science and Technology, University of California at Davis, Davis, CA 95616
| | - Nilesh Maharaj
- Department of Plant Pathology, University of California at Davis, Davis, CA 95616
| | - Shin-Yi Lin
- Department of Food Science and Technology, University of California at Davis, Davis, CA 95616
| | - Darya O Mishchuk
- Department of Food Science and Technology, University of California at Davis, Davis, CA 95616
| | - Elizabeth Chin
- Department of Food Science and Technology, University of California at Davis, Davis, CA 95616
| | - Kris Godfrey
- Contained Research Facility, University of California at Davis, Davis, CA 95616
| | - Elizabeth Foster
- Contained Research Facility, University of California at Davis, Davis, CA 95616
| | - Marylou Polek
- U.S. Department of Agriculture-Agricultural Research Service National Germplasm Repository, Riverside, CA 92507
| | - Johan H J Leveau
- Department of Plant Pathology, University of California at Davis, Davis, CA 95616
| | - Carolyn M Slupsky
- Department of Food Science and Technology, University of California at Davis, Davis, CA 95616
- Department of Nutrition, University of California at Davis, Davis, CA 95616
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18
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Jiang Y, Zhang CX, Chen R, He SY. Challenging battles of plants with phloem-feeding insects and prokaryotic pathogens. Proc Natl Acad Sci U S A 2019; 116:23390-23397. [PMID: 31712429 PMCID: PMC6876188 DOI: 10.1073/pnas.1915396116] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
For the past 4 decades, intensive molecular studies of mostly leaf mesophyll cell-infecting pathogens and chewing insects have led to compelling models of plant-pathogen and plant-insect interactions. Yet, some of the most devastating pathogens and insect pests live in or feed on the phloem, a systemic tissue belonging to the plant vascular system. Phloem tissues are difficult to study, and phloem-inhabiting pathogens are often impossible to culture, thus limiting our understanding of phloem-insect/pathogen interactions at a molecular level. In this Perspective, we highlight recent literature that reports significant advances in the understanding of phloem interactions with insects and prokaryotic pathogens and attempt to identify critical questions that need attention for future research. It is clear that study of phloem-insect/pathogen interactions represents an exciting frontier of plant science, and influx of new scientific expertise and funding is crucial to achieve faster progress in this important area of research that is integral to global food security.
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Affiliation(s)
- Yanjuan Jiang
- CAS Key Laboratory of Tropical Plant Resources and Sustainable Use, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Kunming 650223, China;
- Center of Economic Botany, Core Botanical Gardens, Chinese Academy of Sciences, Kunming 650223, China
- Department of Energy, Plant Research Laboratory, Michigan State University, East Lansing, MI 48824
- Howard Hughes Medical Institute, Michigan State University, East Lansing, MI 48824
| | - Chuan-Xi Zhang
- State Key Laboratory of Rice Biology and Ministry of Agriculture Key Laboratory of Molecular Biology of Crop Pathogens and Insect Pests, Institute of Insect Science, Zhejiang University, Hangzhou 310058, China
| | - Rongzhi Chen
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430070, China
| | - Sheng Yang He
- Department of Energy, Plant Research Laboratory, Michigan State University, East Lansing, MI 48824;
- Howard Hughes Medical Institute, Michigan State University, East Lansing, MI 48824
- Department of Plant Biology, Michigan State University, East Lansing, MI 48824
- Plant Resilience Institute, Michigan State University, East Lansing, MI 48824
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19
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Jain M, Cai L, Fleites LA, Munoz-Bodnar A, Davis MJ, Gabriel DW. Liberibacter crescens Is a Cultured Surrogate for Functional Genomics of Uncultured Pathogenic ' Candidatus Liberibacter' spp. and Is Naturally Competent for Transformation. PHYTOPATHOLOGY 2019; 109:1811-1819. [PMID: 31090497 DOI: 10.1094/phyto-04-19-0129-r] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
'Candidatus Liberibacter' spp. are uncultured insect endosymbionts and phloem-limited bacterial plant pathogens associated with diseases ranging from severe to nearly asymptomatic. 'Ca. L. asiaticus', causal agent of Huanglongbing or citrus "greening," and 'Ca. L. solanacearum', causal agent of potato zebra chip disease, respectively threaten citrus and potato production worldwide. Research on both pathogens has been stymied by the inability to culture these agents and to reinoculate into any host. Only a single isolate of a single species of Liberibacter, Liberibacter crescens, has been axenically cultured. L. crescens strain BT-1 is genetically tractable to standard molecular manipulation techniques and has been developed as a surrogate model for functional studies of genes, regulatory elements, promoters, and secreted effectors derived from the uncultured pathogenic Liberibacters. Detailed, step-by-step, and highly reproducible protocols for axenic culture, transformation, and targeted gene knockouts of L. crescens are described. In the course of developing these protocols, we found that L. crescens is also naturally competent for direct uptake and homology-guided chromosomal integration of both linear and circular plasmid DNA. The efficiency of natural transformation was about an order of magnitude higher using circular plasmid DNA compared with linearized fragments. Natural transformation using a replicative plasmid was obtained at a rate of approximately 900 transformants per microgram of plasmid, whereas electroporation using the same plasmid resulted in 6 × 104 transformants. Homology-guided marker interruptions using either natural uptake or electroporation of nonreplicative plasmids yielded 10 to 12 transformation events per microgram of DNA, whereas similar interruptions using linear fragments via natural uptake yielded up to 34 transformation events per microgram of DNA.
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Affiliation(s)
- M Jain
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611
| | - L Cai
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611
| | - L A Fleites
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611
| | - A Munoz-Bodnar
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611
| | - M J Davis
- Department of Plant Pathology, Citrus Research and Education Center, University of Florida, Lake Alfred, FL 33850
| | - D W Gabriel
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611
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20
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Host-free biofilm culture of " Candidatus Liberibacter asiaticus," the bacterium associated with Huanglongbing. Biofilm 2019; 1:100005. [PMID: 33447792 PMCID: PMC7798463 DOI: 10.1016/j.bioflm.2019.100005] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 08/27/2019] [Accepted: 08/28/2019] [Indexed: 12/05/2022] Open
Abstract
Inability to culture the phloem-restricted alpha-proteobacterium “Candidatus Liberibacter asiaticus” (“Ca. L. asiaticus”) or the closely related species (“Candidatus Liberibacter americanus” and “Candidatus Liberibacter africanus”) that are associated with Huanglongbing (HLB) hampers the development of effective long-term control strategies for this devastating disease. Here we report successful establishment and long-term maintenance of host-free “Ca. L. asiaticus” cultures, with the bacterium growing within cultured biofilms derived from infected citrus tissue. The biofilms were grown in a newly designed growth medium under specific conditions. The initial biofilm-based culture has been successfully maintained for over two years and has undergone over a dozen subcultures. Multiple independent cultures have been established and maintained in a biofilm reactor system, opening the door to the development of pure culture of “Ca. L. asiaticus” and the use of genetics-based methods to understand and mitigate the spread of HLB.
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