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Bodino N, Cavalieri V, Dongiovanni C, Saponari M, Bosco D. Bioecological Traits of Spittlebugs and Their Implications for the Epidemiology and Control of the Xylella fastidiosa Epidemic in Apulia (Southern Italy). PHYTOPATHOLOGY 2023; 113:1647-1660. [PMID: 36945728 DOI: 10.1094/phyto-12-22-0460-ia] [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
Spatial-temporal dynamics of spittlebug populations, together with transmission biology, are of major importance to outline the disease epidemiology of Xylella fastidiosa subsp. pauca in Apulian olive groves. The spread rate of X. fastidiosa is mainly influenced by (i) the pathogen colonization of the host plant; (ii) the acquisition of the pathogen by the vector from an infected plant, and its inoculation to healthy plants; (iii) the vector population dynamics and abundance at different spatial scales; and (iv) the dispersal of the vector. In this contribution we summarize the recent advances in research on insect vectors' traits-points ii, iii, and iv-focusing on those most relevant to X. fastidiosa epidemic in Apulia. Among the vectors' bioecological traits influencing the X. fastidiosa epidemic in olive trees, we emphasize the following: natural infectivity and transmission efficiency, phenological timing of both nymphal and adult stage, the role of seminatural vegetation as a vector reservoir in the agroecosystem and landscape, and preferential and directional dispersal capabilities. Despite the research on X. fastidiosa vectors carried out in Europe in the last decade, key uncertainties on insect vectors remain, hampering a thorough understanding of pathogen epidemiology and the development of effective and targeted management strategies. Our goal is to provide a structured and contextualized review of knowledge on X. fastidiosa vectors' key traits in the Apulian epidemic, highlighting information gaps and stimulating novel research pathways on X. fastidiosa pathosystems in Europe. [Formula: see text] Copyright © 2023 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)
- Nicola Bodino
- CNR-Istituto per la Protezione Sostenibile delle Piante, 10135 Torino, Italy
| | - Vincenzo Cavalieri
- CNR-Istituto per la Protezione Sostenibile delle Piante, SS Bari, 70126 Bari, Italy
| | - Crescenza Dongiovanni
- CRSFA-Centro di Ricerca, Sperimentazione e Formazione in Agricoltura Basile Caramia, 70010 Locorotondo (BA), Italy
| | - Maria Saponari
- CNR-Istituto per la Protezione Sostenibile delle Piante, SS Bari, 70126 Bari, Italy
| | - Domenico Bosco
- CNR-Istituto per la Protezione Sostenibile delle Piante, 10135 Torino, Italy
- Dipartimento di Scienze Agrarie, Forestali e Alimentari, Università degli Studi di Torino, 10095 Grugliasco (TO), Italy
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Zhang P, Ma X, Liu L, Mao C, Hu Y, Yan B, Guo J, Liu X, Shi J, Lee GS, Pan X, Deng Y, Zhang Z, Kang Z, Qiao Y. MEDIATOR SUBUNIT 16 negatively regulates rice immunity by modulating PATHOGENESIS RELATED 3 activity. PLANT PHYSIOLOGY 2023; 192:1132-1150. [PMID: 36815292 PMCID: PMC10231465 DOI: 10.1093/plphys/kiad120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 01/19/2023] [Accepted: 01/20/2023] [Indexed: 06/01/2023]
Abstract
Lesion mimic mutants (LMMs) are valuable genetic resources for unraveling plant defense responses including programmed cell death. Here, we identified a rice (Oryza sativa) LMM, spotted leaf 38 (spl38), and demonstrated that spl38 is essential for the formation of hypersensitive response-like lesions and innate immunity. Map-based cloning revealed that SPL38 encodes MEDIATOR SUBUNIT 16 (OsMED16). The spl38 mutant showed enhanced resistance to rice pathogens Magnaporthe oryzae and Xanthomonas oryzae pv. oryzae (Xoo) and exhibited delayed flowering, while OsMED16-overexpressing plants showed increased rice susceptibility to M. oryzae. The OsMED16-edited rice lines were phenotypically similar to the spl38 mutant but were extremely weak, exhibited growth retardation, and eventually died. The C-terminus of OsMED16 showed interaction with the positive immune regulator PATHOGENESIS RELATED 3 (OsPR3), resulting in the competitive repression of its chitinase and chitin-binding activities. Furthermore, the ospr3 osmed16 double mutants did not exhibit the lesion mimic phenotype of the spl38 mutant. Strikingly, OsMED16 exhibited an opposite function in plant defense relative to that of Arabidopsis (Arabidopsis thaliana) AtMED16, most likely because of 2 amino acid substitutions between the monocot and dicot MED16s tested. Collectively, our findings suggest that OsMED16 negatively regulates cell death and immunity in rice, probably via the OsPR3-mediated chitin signaling pathway.
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Affiliation(s)
- Peng Zhang
- Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Shanghai 200234, China
- College of Agriculture, Yangtze University, Jingzhou 434025, China
| | - Xiaoding Ma
- National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Lina Liu
- Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Shanghai 200234, China
| | - Chanjuan Mao
- Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Shanghai 200234, China
| | - Yongkang Hu
- Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Shanghai 200234, China
| | - Bingxiao Yan
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Jia Guo
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling 712100, China
| | - Xinyu Liu
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
| | - Jinxia Shi
- Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Shanghai 200234, China
| | - Gang-Seob Lee
- National Institute of Agricultural Science, Jeon Ju 54874, Republic of Korea
| | - Xiaowu Pan
- Hunan Rice Research Institute, Hunan Academy of Agricultural Sciences, Changsha 410125, China
| | - Yiwen Deng
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Zhengguang Zhang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
| | - Zhensheng Kang
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling 712100, China
| | - Yongli Qiao
- Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Shanghai 200234, China
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De La Fuente L, Merfa MV, Cobine PA, Coleman JJ. Pathogen Adaptation to the Xylem Environment. ANNUAL REVIEW OF PHYTOPATHOLOGY 2022; 60:163-186. [PMID: 35472277 DOI: 10.1146/annurev-phyto-021021-041716] [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: 06/14/2023]
Abstract
A group of aggressive pathogens have evolved to colonize the plant xylem. In this vascular tissue, where water and nutrients are transported from the roots to the rest of the plant, pathogens must be able to thrive under acropetal xylem sap flow and scarcity of nutrients while having direct contact only with predominantly dead cells. Nevertheless, a few bacteria have adapted to exclusively live in the xylem, and various pathogens may colonize other plant niches without causing symptoms unless they reach the xylem. Once established, the pathogens modulate its physicochemical conditions to enhance their growth and virulence. Adaptation to the restrictive lifestyle of the xylem leads to genome reduction in xylem-restricted bacteria, as they have a higher proportion of pseudogenes in their genome. The basis of xylem adaptation is not completely understood; therefore, a need still exists for model systems to advance the knowledge on this topic.
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Affiliation(s)
- Leonardo De La Fuente
- 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;
| | - Paul A Cobine
- Department of Biological Sciences, Auburn University, Auburn, Alabama, USA
| | - Jeffrey J Coleman
- Department of Entomology and Plant Pathology, Auburn University, Auburn, Alabama, USA;
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Bossi Esteves M, Lopes Nalin J, Kudlawiec K, Caserta Salviatto R, de Melo Sales T, Sicard A, Piacentini Paes de Almeida R, Alves de Souza A, Roberto Spotti Lopes J. XadA2 Adhesin Decreases Biofilm Formation and Transmission of Xylella fastidiosa subsp. pauca. INSECTS 2020; 11:insects11080473. [PMID: 32722654 PMCID: PMC7469142 DOI: 10.3390/insects11080473] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 07/21/2020] [Accepted: 07/21/2020] [Indexed: 11/16/2022]
Abstract
Xylella fastidiosa is a vector-borne bacterium that causes diseases in many plants of economic interest. The bacterium-vector initial interactions involve bacterial membrane-bound adhesins that mediate cell attachment to the foregut of insect vectors. We investigated the role of the afimbrial adhesin XadA2 in the binding and biofilm formation of X. fastidiosa subsp. pauca to vector surfaces in vitro, as well as its potential to disrupt pathogen transmission. We showed that XadA2 has binding affinity for polysaccharides on sharpshooter hindwings, used as a proxy for the interactions between X. fastidiosa and vectors. When in a medium without carbon sources, the bacterium used wing components, likely chitin, as a source of nutrients and formed a biofilm on the wing surface. There was a significant reduction in X. fastidiosa biofilm formation and cell aggregation on vector wings in competition assays with XadA2 or its specific antibody (anti-XadA2). Finally, pathogen acquisition and transmission to plant were significantly reduced when the vectors acquired X. fastidiosa from an artificial diet supplemented with anti-XadA2. These results show that XadA2 is important in mediating bacterial colonization in the insect and that it could be used as a target for blocking X. fastidiosa transmission.
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Affiliation(s)
- Mariana Bossi Esteves
- Departamento de Entomologia e Acarologia, Escola Superior de Agricultura “Luiz de Queiroz” (ESALQ), Universidade de São Paulo (USP), Piracicaba, SP 13418-900, Brazil; (J.L.N.); (K.K.); (J.R.S.L.)
- Correspondence: ; Tel.: +55-19-9910-22563
| | - Julia Lopes Nalin
- Departamento de Entomologia e Acarologia, Escola Superior de Agricultura “Luiz de Queiroz” (ESALQ), Universidade de São Paulo (USP), Piracicaba, SP 13418-900, Brazil; (J.L.N.); (K.K.); (J.R.S.L.)
| | - Karla Kudlawiec
- Departamento de Entomologia e Acarologia, Escola Superior de Agricultura “Luiz de Queiroz” (ESALQ), Universidade de São Paulo (USP), Piracicaba, SP 13418-900, Brazil; (J.L.N.); (K.K.); (J.R.S.L.)
| | - Raquel Caserta Salviatto
- Centro de Citricultura “Sylvio Moreira”, Instituto Agronômico, Cordeirópolis, SP 13490-970, Brazil; (R.C.S.); (A.A.d.S.)
| | | | - Anne Sicard
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 94720-3114, USA; (A.S.); (R.P.P.d.A.)
| | - Rodrigo Piacentini Paes de Almeida
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 94720-3114, USA; (A.S.); (R.P.P.d.A.)
| | - Alessandra Alves de Souza
- Centro de Citricultura “Sylvio Moreira”, Instituto Agronômico, Cordeirópolis, SP 13490-970, Brazil; (R.C.S.); (A.A.d.S.)
| | - João Roberto Spotti Lopes
- Departamento de Entomologia e Acarologia, Escola Superior de Agricultura “Luiz de Queiroz” (ESALQ), Universidade de São Paulo (USP), Piracicaba, SP 13418-900, Brazil; (J.L.N.); (K.K.); (J.R.S.L.)
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5
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Abstract
Xylella fastidiosa is one of the most important threats to plant health worldwide, causing disease in the Americas on a range of agricultural crops and trees, and recently associated with a critical epidemic affecting olive trees in Europe. A main challenge for the detection of the pathogen and the development of physiological studies is its fastidious growth, as the generation time can vary from 10 to 100 h for some strains. This physiological peculiarity is shared with several human pathogens and is poorly understood. We performed an analysis of the metabolic capabilities of X. fastidiosa through a genome-scale metabolic model of the bacterium. This model was reconstructed and manually curated using experiments and bibliographical evidence. Our study revealed that fastidious growth most probably results from different metabolic specificities such as the absence of highly efficient enzymes or a global inefficiency in virulence factor production. These results support the idea that the fragility of the metabolic network may have been shaped during evolution to lead to the self-limiting behavior of X. fastidiosa. High proliferation rate and robustness are vital characteristics of bacterial pathogens that successfully colonize their hosts. The observation of drastically slow growth in some pathogens is thus paradoxical and remains unexplained. In this study, we sought to understand the slow (fastidious) growth of the plant pathogen Xylella fastidiosa. Using genome-scale metabolic network reconstruction, modeling, and experimental validation, we explored its metabolic capabilities. Despite genome reduction and slow growth, the pathogen’s metabolic network is complete but strikingly minimalist and lacking in robustness. Most alternative reactions were missing, especially those favoring fast growth, and were replaced by less efficient paths. We also found that the production of some virulence factors imposes a heavy burden on growth. Interestingly, some specific determinants of fastidious growth were also found in other slow-growing pathogens, enriching the view that these metabolic peculiarities are a pathogenicity strategy to remain at a low population level. IMPORTANCEXylella fastidiosa is one of the most important threats to plant health worldwide, causing disease in the Americas on a range of agricultural crops and trees, and recently associated with a critical epidemic affecting olive trees in Europe. A main challenge for the detection of the pathogen and the development of physiological studies is its fastidious growth, as the generation time can vary from 10 to 100 h for some strains. This physiological peculiarity is shared with several human pathogens and is poorly understood. We performed an analysis of the metabolic capabilities of X. fastidiosa through a genome-scale metabolic model of the bacterium. This model was reconstructed and manually curated using experiments and bibliographical evidence. Our study revealed that fastidious growth most probably results from different metabolic specificities such as the absence of highly efficient enzymes or a global inefficiency in virulence factor production. These results support the idea that the fragility of the metabolic network may have been shaped during evolution to lead to the self-limiting behavior of X. fastidiosa.
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Sicard A, Castillo AI, Voeltz M, Chen H, Zeilinger AR, De La Fuente L, Almeida RPP. Inference of Bacterial Pathogen Instantaneous Population Growth Dynamics. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2020; 33:402-411. [PMID: 31972098 DOI: 10.1094/mpmi-10-19-0274-ta] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Although bacterial host colonization is a dynamic process that requires population growth, studies often focus on comparing bacterial populations at a given time point. However, this may not reflect the dynamics of the colonization process. Time-course assays provide important insights into the dynamics of host colonization but are laborious and may still lack resolution for immediate processes affecting populations. An alternative way to address this issue, using widely accessible tools (such as quantitative PCR [qPCR]), is to take advantage of the relationship between bacterial chromosomal replication and cell division to determine population growth status at the sampling time. Conceptually, the ratio between the number of copies at the origin of replication and that at the terminus of replication should be correlated with the measured bacterial growth rate. This peak-to-trough ratio (PTR) to estimate instantaneous population growth status was tested with the slow-growing plant-pathogenic bacterium Xylella fastidiosa. We found no correlation between PTR and the measured growth rate when using genome-level data but overall sequencing depth of coverage trends matched theoretical expectations. On the other hand, the population growth status of X. fastidiosa was predicted by PTR when using qPCR data, which was improved by the pretreatment of cells with a photoreactive DNA-binding dye. Our results suggest that PTR could be used to determine X. fastidiosa growth status both in planta and in insect vectors. We expect PTR will perform better with fast-growing bacterial pathogens, potentially becoming a powerful tool for easily and quickly assessing population growth status.
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Affiliation(s)
- Anne Sicard
- Department of Environmental Science, Policy and Management, University of California, Berkeley, CA, U.S.A
| | - Andreina I Castillo
- Department of Environmental Science, Policy and Management, University of California, Berkeley, CA, U.S.A
| | - Michael Voeltz
- Department of Environmental Science, Policy and Management, University of California, Berkeley, CA, U.S.A
| | - Hongyu Chen
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL, U.S.A
| | - Adam R Zeilinger
- Department of Environmental Science, Policy and Management, University of California, Berkeley, CA, U.S.A
| | | | - Rodrigo P P Almeida
- Department of Environmental Science, Policy and Management, University of California, Berkeley, CA, U.S.A
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7
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Ranieri E, Zitti G, Riolo P, Isidoro N, Ruschioni S, Brocchini M, Almeida RPP. Fluid dynamics in the functional foregut of xylem-sap feeding insects: A comparative study of two Xylella fastidiosa vectors. JOURNAL OF INSECT PHYSIOLOGY 2020; 120:103995. [PMID: 31837986 DOI: 10.1016/j.jinsphys.2019.103995] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Revised: 11/28/2019] [Accepted: 12/08/2019] [Indexed: 06/10/2023]
Abstract
Xylem sap sucking insects are adapted to ingest fluids under tension. Although much has been learned about such feeding strategy, this adaptation still poses several unresolved questions, including how these insects ingest against strong xylem sap tension. Xylem sap-feeding insects are vectors of the plant pathogenic xylem-limited bacterium Xylella fastidiosa. This bacterium colonizes the cuticular lining of the foregut of vectors in a persistent manner. We used micro-computed tomography and scanning electron microscopy to investigate the foregut morphometry of two X. fastidiosa vector species: Philaenus spumarius and Graphocephala atropunctata (Hemiptera: Aphrophoridae and Cicadellidae, respectively). On the basis of morphometric data, we built a hydrodynamic model of the foregut of these two insect species, focusing on the precibarium, a region previously shown to be colonized by X. fastidiosa and correlated with pathogen acquisition from and inoculation to plants. Our data show that space in the P. spumarius functional foregut could potentially harbor twice as many cells as similar space in G. atropunctata, although the opposite trend has been observed with biological samples. Average flow velocity of ingested fluid depended on the percentage of the cibarium volume exploited for suction: if the entire volume were used, velocities were in the range of meters per second. In contrast, velocities on the order of those found in the literature (about 10 cm/s) were attained if only 5% of the cibarium volume were exploited. Simulated bacterial colonization of the foregut was analyzed in relation to hydrodynamics and pressure needed for insects to ingest. Our model is designed to represent the diameter reduction of the food canal in both insect species when infected with X. fastidiosa. Results indicated that full bacterial colonization significantly increased the mean sap-sucking flow velocity. In particular, the colonization increased the maximum section-averaged velocity in the G. atropunctata more than two times and the net pressure needed to mantain the flow in the precibarium when colonized is relevant (about 0.151 MPa) if compared to a standard xylem sap tension (1 MPa). Bacterial colonization also influenced the sucking process of the G. atropunctata, by hindering the formation of a recirculation zone (or eddy), that characterizd the flow in the distal part of the precibarium when bacteria were absent. On the other hand, considering the pressure the insect must generate to feed, X. fastidiosa colonization probably influences fitness of the G. atropunctata more than that of P. spumarius.
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Affiliation(s)
- Emanuele Ranieri
- Dipartimento di Scienze Agrarie, Alimentari e Ambientali - Università Politecnica delle Marche, Ancona, Italy
| | - Gianluca Zitti
- Dipartimento Ingegneria Civile, Edile e dell'Architettura - Università Politecnica delle Marche, Ancona, Italy.
| | - Paola Riolo
- Dipartimento di Scienze Agrarie, Alimentari e Ambientali - Università Politecnica delle Marche, Ancona, Italy
| | - Nunzio Isidoro
- Dipartimento di Scienze Agrarie, Alimentari e Ambientali - Università Politecnica delle Marche, Ancona, Italy
| | - Sara Ruschioni
- Dipartimento di Scienze Agrarie, Alimentari e Ambientali - Università Politecnica delle Marche, Ancona, Italy
| | - Maurizio Brocchini
- Dipartimento Ingegneria Civile, Edile e dell'Architettura - Università Politecnica delle Marche, Ancona, Italy
| | - Rodrigo P P Almeida
- Department of Environmental Science, Policy and Management - University of California, Berkeley, Berkeley, CA, USA
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Sicard A, Merfa MV, Voeltz M, Zeilinger AR, De La Fuente L, Almeida RPP. Discriminating between viable and membrane-damaged cells of the plant pathogen Xylella fastidiosa. PLoS One 2019; 14:e0221119. [PMID: 31442247 PMCID: PMC6707623 DOI: 10.1371/journal.pone.0221119] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Accepted: 07/30/2019] [Indexed: 12/31/2022] Open
Abstract
Xylella fastidiosa is a plant pathogenic bacterium with devastating consequences to several crops of economic importance across the world. While this pathogen has been studied for over a century in the United States, several aspects of its biology remain to be investigated. Determining the physiological state of bacteria is essential to understand the effects of its interactions with different biotic and abiotic factors on cell viability. Although X. fastidiosa is culturable, its slow growing nature makes this technique cumbersome to assess the physiological state of cells present in a given environment. PMA-qPCR, i.e. the use of quantitative PCR combined with the pre-treatment of cells with the dye propidium monoazide, has been successfully used in a number of studies on human pathogens to calculate the proportion of viable cells, but has less frequently been tested on plant pathogens. We found that the use of a version of PMA, PMAxx, facilitated distinguishing between viable and non-viable cells based on cell membrane integrity in vitro and in planta. Additional experiments comparing the number of culturable, viable, and total cells in planta would help further confirm our initial results. Enhancers, intended to improve the efficacy of PMAxx, were not effective and appeared to be slightly toxic to X. fastidiosa.
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Affiliation(s)
- Anne Sicard
- Department of Environmental Science, Policy and Management, University of California, Berkeley, California, United States of America
| | - Marcus V. Merfa
- Department of Entomology and Plant Pathology, Auburn University, Auburn, Alabama, United States of America
| | - Michael Voeltz
- Department of Environmental Science, Policy and Management, University of California, Berkeley, California, United States of America
| | - Adam R. Zeilinger
- Department of Environmental Science, Policy and Management, University of California, Berkeley, California, United States of America
| | - Leonardo De La Fuente
- Department of Entomology and Plant Pathology, Auburn University, Auburn, Alabama, United States of America
| | - Rodrigo P. P. Almeida
- Department of Environmental Science, Policy and Management, University of California, Berkeley, California, United States of America
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Dandekar AM, Jacobson A, Ibáñez AM, Gouran H, Dolan DL, Agüero CB, Uratsu SL, Just R, Zaini PA. Trans-Graft Protection Against Pierce's Disease Mediated by Transgenic Grapevine Rootstocks. FRONTIERS IN PLANT SCIENCE 2019; 10:84. [PMID: 30787937 PMCID: PMC6372540 DOI: 10.3389/fpls.2019.00084] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Accepted: 01/21/2019] [Indexed: 05/03/2023]
Abstract
A field study showed that transgenic grapevine rootstocks can provide trans-graft-mediated protection to a wild type scion against Pierce's disease (PD) development. We individually field-tested two distinct strategies. The first expressed a chimeric antimicrobial protein (CAP) that targeted the functionality of the lipopolysaccharide (LPS) surface of Xylella fastidiosa (Xf), the causative agent of PD. The second expressed a plant polygalacturonase inhibitory protein (PGIP) that prevents PD by inhibiting breakdown of pectin present in primary cell walls. Both proteins are secreted to the apoplast and then into the xylem, where they migrate past the graft union, transiting into the xylem of the grafted scion. Transgenic Vitis vinifera cv. Thompson Seedless (TS) expressing ether CAP or PGIP were tested in the greenhouse and those lines that showed resistance to PD were grafted with wild type TS scions. Grafted grapevines were introduced into the field and tested over 7 years. Here we present data on the field evaluation of trans-graft protection using four CAP and four PGIP independent rootstock lines, compared to an untransformed rootstock. There was 30 to 95% reduction in vine mortality among CAP- and PGIP-expressing lines after three successive yearly infections with virulent Xf. Shoot tissues grafted to either CAP or PGIP transgenic rootstocks supported lower pathogen titers and showed fewer disease symptoms. Grafted plants on transgenic rootstocks also had more spring bud break following infection, more shoots, and more vigorous growth compared to those grafted to wild type rootstocks. No yield penalty was observed in the transgenic lines and some PGIP-expressing vines had enhanced yield potential. Trans-graft protection is an efficient way to protect grape scions against PD while preserving their valuable varietal genotypes and clonal properties.
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Affiliation(s)
- Abhaya M. Dandekar
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
| | - Aaron Jacobson
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
| | - Ana M. Ibáñez
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
| | - Hossein Gouran
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
| | - David L. Dolan
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
| | - Cecilia B. Agüero
- Department of Enology and Viticulture, University of California, Davis, Davis, CA, United States
| | - Sandie L. Uratsu
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
| | - Robert Just
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
| | - Paulo A. Zaini
- Department of Plant Sciences, University of California, Davis, Davis, CA, United States
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10
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Sicard A, Zeilinger AR, Vanhove M, Schartel TE, Beal DJ, Daugherty MP, Almeida RPP. Xylella fastidiosa: Insights into an Emerging Plant Pathogen. ANNUAL REVIEW OF PHYTOPATHOLOGY 2018; 56:181-202. [PMID: 29889627 DOI: 10.1146/annurev-phyto-080417-045849] [Citation(s) in RCA: 114] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The bacterium Xylella fastidiosa re-emerged as a plant pathogen of global importance in 2013 when it was first associated with an olive tree disease epidemic in Italy. The current threat to Europe and the Mediterranean basin, as well as other world regions, has increased as multiple X. fastidiosa genotypes have now been detected in Italy, France, and Spain. Although X. fastidiosa has been studied in the Americas for more than a century, there are no therapeutic solutions to suppress disease development in infected plants. Furthermore, because X. fastidiosa is an obligatory plant and insect vector colonizer, the epidemiology and dynamics of each pathosystem are distinct. They depend on the ecological interplay of plant, pathogen, and vector and on how interactions are affected by biotic and abiotic factors, including anthropogenic activities and policy decisions. Our goal with this review is to stimulate discussion and novel research by contextualizing available knowledge on X. fastidiosa and how it may be applicable to emerging diseases.
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Affiliation(s)
- Anne Sicard
- Department of Environmental Science, Policy and Management, University of California, Berkeley, California 94720, USA;
- Biologie et Génétique des Interactions Plant-Parasite, UMR 0385, Centre de Coopération Internationale en Recherche Agronomique pour le Développement-Institut National de la Recherche Agronomique-Montpellier SupAgro, Campus International de Baillarguet, 34398 Montpellier CEDEX 05, France
| | - Adam R Zeilinger
- Department of Environmental Science, Policy and Management, University of California, Berkeley, California 94720, USA;
| | - Mathieu Vanhove
- Department of Environmental Science, Policy and Management, University of California, Berkeley, California 94720, USA;
| | - Tyler E Schartel
- Department of Entomology, University of California, Riverside, California 92521, USA
| | - Dylan J Beal
- Department of Environmental Science, Policy and Management, University of California, Berkeley, California 94720, USA;
| | - Matthew P Daugherty
- Department of Entomology, University of California, Riverside, California 92521, USA
| | - Rodrigo P P Almeida
- Department of Environmental Science, Policy and Management, University of California, Berkeley, California 94720, USA;
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Rapicavoli J, Ingel B, Blanco‐Ulate B, Cantu D, Roper C. Xylella fastidiosa: an examination of a re-emerging plant pathogen. MOLECULAR PLANT PATHOLOGY 2018; 19:786-800. [PMID: 28742234 PMCID: PMC6637975 DOI: 10.1111/mpp.12585] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2017] [Revised: 07/13/2017] [Accepted: 07/19/2017] [Indexed: 05/10/2023]
Abstract
UNLABELLED Xylella fastidiosa is a Gram-negative bacterial plant pathogen with an extremely wide host range. This species has recently been resolved into subspecies that correlate with host specificity. This review focuses on the status of X. fastidiosa pathogenic associations in plant hosts in which the bacterium is either endemic or has been recently introduced. Plant diseases associated with X. fastidiosa have been documented for over a century, and much about what is known in the context of host-pathogen interactions is based on these hosts, such as grape and citrus, in which this pathogen has been well described. Recent attention has focused on newly emerging X. fastidiosa diseases, such as in olives. TAXONOMY Bacteria; Gammaproteobacteria; family Xanthomonadaceae; genus Xylella; species fastidiosa. MICROBIOLOGICAL PROPERTIES Gram-negative rod (0.25-0.35 × 0.9-3.5 μm), non-flagellate, motile via Type IV pili-mediated twitching, fastidious. HOST RANGE Xylella fastidiosa has a broad host range that includes ornamental, ecological and agricultural plants belonging to over 300 different species in 63 different families. To date, X. fastidiosa has been found to be pathogenic in over 100 plant species. In addition, it can establish non-symptomatic associations with many plants as a commensal endophyte. Here, we list the four distinct subspecies of X. fastidiosa and some of the agriculturally relevant diseases caused by them: X. fastidiosa ssp. fastidiosa causes Pierce's disease (PD) of grapevine (Vitis vinifera); X. fastidiosa ssp. multiplex causes almond leaf scorch (ALS) and diseases on other nut and shade tree crops; X. fastidiosa ssp. pauca causes citrus variegated chlorosis (CVC) (Citrus spp.), coffee leaf scorch and olive quick decline syndrome (OQDS) (Olea europaea); X. fastidiosa ssp. sandyi causes oleander leaf scorch (OLS) (Nerium oleander). Significant host specificity seemingly exists for some of the subspecies, although this could be a result of technical biases based on the limited number of plants tested, whereas some subspecies are not as stringent in their host range and can infect several plant hosts. DISEASE SYMPTOMS Most X. fastidiosa-related diseases appear as marginal leaf necrosis and scorching of the leaves. In the case of PD, X. fastidiosa can also cause desiccation of berries (termed 'raisining'), irregular periderm development and abnormal abscission of petioles. In olive trees affected with OQDS, leaves exhibit marginal necrosis and defoliation, and overall tree decline occurs. Plants with ALS and OLS also exhibit the characteristic leaf scorch symptoms. Not all X. fastidiosa-related diseases exhibit the typical leaf scorch symptoms. These include CVC and Phony Peach disease, amongst others. In the case of CVC, symptoms include foliar wilt and interveinal chlorosis on the upper surfaces of the leaves (similar to zinc deficiency), which correspond to necrotic, gum-like regions on the undersides of the leaves. Additional symptoms of CVC include defoliation, dieback and hardening of fruits. Plants infected with Phony Peach disease exhibit a denser, more compact canopy (as a result of shortened internodes, darker green leaves and delayed leaf senescence), premature bloom and reduced fruit size. Some occlusions occur in the xylem vessels, but there are no foliar wilting, chlorosis or necrosis symptoms . USEFUL WEBSITES: http://www.piercesdisease.org/; https://pubmlst.org/xfastidiosa/; http://www.xylella.lncc.br/; https://nature.berkeley.edu/xylella/; https://ec.europa.eu/food/plant/plant_health_biosecurity/legislation/emergency_measures/xylella-fastidiosa_en.
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Affiliation(s)
- Jeannette Rapicavoli
- Department of Plant Pathology and MicrobiologyUniversity of CaliforniaRiversideCA 92521USA
| | - Brian Ingel
- Department of Plant Pathology and MicrobiologyUniversity of CaliforniaRiversideCA 92521USA
| | | | - Dario Cantu
- Department of Viticulture and EnologyUniversity of CaliforniaDavisCA 95616USA
| | - Caroline Roper
- Department of Plant Pathology and MicrobiologyUniversity of CaliforniaRiversideCA 92521USA
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