Ralstonia solanacearum - wiki

Ralstonia solanacearum Ralstonia solanacearum is an aerobic non-sporing, Gram-negative plant pathogenic bacterium R solanacearum is soil-borne and motile with a polar flagellar tuft It colonises the xylem, causing bacterial wilt in a very wide range of potential host plants It is known as Granville wilt when it occurs in tobacco Bacterial wilts of tomato, pepper, eggplant and Irish potato caused by Ralstonia solanacearum were among the first diseases that Erwin Frink Smith proved to be caused by a bacterial pathogen Because of its devastating lethality, R solanacearum is now of the more intensively studied phytopathogenic bacteria and bacterial wilt of tomato is a model system for investigating mechanisms of pathogenesis.[1] Ralstonia was recently classified as Pseudomonas with similarity in most aspects, except that it does not produce fluorescent pigment like Pseudomonas.[2] The genome of R solanacearum Strain GMI1000 has been sequenced.[3] Within the R solanacearum species complex, there are four major Photograph of tomato plant with Ralstonia wilt symptoms Clemmonophyletic clusters of strains, termed phylotypes, that son University - USDA Cooperative Extension Slide Series are geographically distinct: phylotypes I-IV are found in Asia, America, Africa, and Oceania, respectively.[1] R solanacearum was once considered as a possible bi- Wild hosts ological control of Kahili Ginger (Hedychium gardnerianum), which is a member of '100 of the World’s • Woody nightshade (Solanum dulcamara) Worst Invasive Alien Species’ in 2004.[4] However, R solanacearum is no longer used as a biological control for Kahili Ginger in Hawaiian forests because of its wide host 1.2 Symptoms range The ginger strain infects numerous ginger species, including edible ginger (Zingiber officinale), shampoo Geranium:[7] ginger (Zingiber zerumbet, pink ginger (Alpinia purpurata) and red ginger (Alpinia purpurata).[5] • Wilting begins with lower leaves and petioles and works its way up the plant Hosts and symptoms 1.1 • Wilted leaves with chlorotic, wedge-shaped areas or chlorotic and/or necrotic leaf margins No leaf spots are evident Hosts • Eventually entire plant collapses on the medium Plant hosts that R solanacearum infects includes: • White runny ooze from cut stems Crops Potato:[7] • Potato (Solanum tuberosum); Tomato (Lycopersicum esculentum); Aubergine (egg plant) (Solanum melongena); Banana, (Musa spp); Geranium (common name) (Pelargonium); Ginger (Zingiber officinale); Tobacco (Nicotiana tabacum); Sweet pepper (Capsicum spp); Olive (Olea europea); Rose (Rosa); Soybeans (Glycine max).[6] • Wilting of the leaves at the end of the day with recovery at night Plant will eventually fail to recover and die • Brown staining of vascular ring Pus may exude from the ring when the tuber is squeezed VIRULENCE MECHANISMS • Pale ooze may exude from eyes and heel end of phytopathogenic bacteria, Ralstonia solanacearum potenpotato Soil will adhere to the oozing eyes tially requires only one entry site to establish a systemic infection that results in bacterial wilt.[1] • Cross-section of a stem placed in water will exude After invading a susceptible host, R solanacearum mulmilky white strands tiplies and moves systematically within the plant before • Unlike the fungal wilts, the leaves remains green in bacterial wilt symptoms occur (Wilting should be considered as the most visible side effect that usually occurs bacterial wilt after extensive colonization of the pathogen) When the pathogen gets into the xylems through natural openings or wounds, tyloses may form to block the axial migra2 Disease cycle tion of bacteria within the plant In susceptible plants, this sometimes happens slowly and infrequently to prevent pathogen migration, and may instead lead to vascu2.1 Survival lar dysfunction by unspecifically obstructing uncolonized Ralstonia solanacearum can overwinter in plant debris or vessels diseased plants, wild hosts, seeds or vegetative propaga- Wilting occurs at high level of bacterial population in tive organs like tubers The bacteria can survive for a the xylem and is partially due to vascular dysfunction long time in water (up to 40 years at 20–25 °C in pure in which water cannot reach the leaves sufficiently At water) and the bacterial population is reduced in extreme this time, extracellular polysaccharide (EPS1) content is conditions (temperature, pH, salts, e.g.) Infected land about 10 μg/g tissue in the taproot, hypocotyl and midsometimes cannot be used again for susceptible crops for stem; EPS1 concentration is higher later on at more than several years R solanacearum can also survive in cool 100 μg/g tissuein fully wilted plant Wilting is due to weather and enter a state of being viable but not cul- vascular dysfunction that prevent water from reaching turable In most cases, this stage is not an agricultural the leaves Ralstonia’s systemic toxin also causes loss threat because the bacteria usually become avirulent af- of stomatal control but there is no evidence for excester recovering.[1] sive transpiration as its consequence The primary factor 2.2 Dispersal R solanacearum causes wilting at high population (108 – 1010 cfu/g tissue) and disperses in several routes The large number of R solanacearum can shed from roots of symptomatic and non-symptomatic plants Beside that, bacterial ooze (which is usually used as a sign for detection)on plant surfaces, can enter the surrounding soil or water, contaminating farming equipment or may be acquired by insect vectors.[1] In addition, this pathogen can be spread out by contaminated flood water, irrigation, contaminated tools or infected seeds In northern Europe, the pathogen has become established in solanaceous weeds which grow in slow moving rivers When such contaminated water is used to irrigate potatoes, the pathogen enters the potato production system Some EU states and Middle Eastern countries have not yet been able to eradicate this pathogen 2.3 Infection contributing to wilting is probably blocking of pit membranes in the petioles and leaves by the high molecular mass EPS1 High bacterial densities, byproducts of plant cell wall degradation; tyloses and gums produced by the plant itself are other contributing factors to wilting.[1] Virulence mechanisms R solanacearum possesses genes for all six protein secretion pathways that have been characterized in Gramnegative bacteria Perhaps the best-studied of these is the Type III secretion system (T3SS or TTSS), which secretes infection-promoting effector proteins (T3Es) into host cells Approximately 74 suspected or confirmed T3Es have been identified in R solanacearum to date, although the functions of very few are currently known Despite being just one of several protein secretion systems, the T3SS is necessary for R solanacearum to cause disease.[8] No single effector protein has been found to significantly alter pathogenicity of R solanacearum, but simultaneous disruption of certain subsets of effectors (such as the set of seven GALA effectors in strain GMI1000) strongly affects virulence of the pathogen GALA is necessary for virulence on Medicago truncatula, hinting that T3E diversity may play a role in determining the broad host range of the R solanacearum species complex.[9] R solanacearum usually enter the plant via a wound Natural wounds (created by excision of flowers, genesis of lateral roots) as well as unnatural ones (by agricultural practices or nematodes and xylem-feeding bugs attack) would become entry sites for Ralstonia solanacearum The bacteria get access to the wounds partially by flagellar-mediated swimming motility and The Type III secretion system is not unique to R chemotaxic attraction toward root exudates Unlike many solanacearum and is, in fact, very ancient The evolu- 5.2 Specific host plant symptoms and management tionary history of the T3SS is contested; a high degree a good rotation system that follows susceptible crops with of similarity to the flagellum has sparked debate over the resistant or non-host crops can assist in diminishing the relationship between these two structures.[1] pathogen.[1] The pathogen is listed as a Select Agent in Approximately half of T3SS proteins are highly con- the United States; if the pathogen is detected by a proper served in R solanacearum and likely constitute a very authority a number of management protocols may be imold and stabilized effector core.[10] Among the other plemented These can range from surveys to quaranhalf showing variation among different strains of R tines of infected and potentially infected plant material, may lead to larger eradication and sanitation solanacearum, only a third show evidence of lateral gene which in turn programs.[14] transfer The origins of the remaining effectors are unknown, although some researchers hypothesize that gene-for-gene interactions may play a significant role in shaping virulence genes in R solanacearum.[11][12] 5.2 Specific host plant symptoms and management Some of these effector proteins are homologous to Transcription Activator-like effectors (TAL effectors) from Xanthomonas [13] and could possibly have a similar func- 5.3 Potato tion of activating specific genes in the host plant cells during R solanacearum pathogenesis Wilting and yellowing of the leaves as well as overall stunting of the plant are typical symptoms.[16] The leaves may also take on a bronze cast[17] along with stems becoming streaked and tuber eyes becoming discolored Environment Tubers will also start to rot if left in the ground General sanitation practices are recommended to prevent spread The environment that Ralstonia solanacearum is comof the disease as chemical control is ineffective Crop romonly found in is affected by the particular race (a getation with resistant crops is useful as well as altering the netically diverse population within a species), and the pH of the soil keeping it low in the summer (4-5), and particular biovar (a strain that differs physiologically or higher in the fall (6.)[17] biochemically from other strains.) Race 1, race biovar 1, and race biovar are three of the most common and important strains of Ralstonia solanacearum Race strains have a broad host range including tobacco and 5.4 Tomato bananas, and are usually found in tropical and subtropical environments as they have trouble surviving cooler Younger leaves of the plant will become flaccid, and adtemperatures, and are endemic to the southeastern United ventitious roots may appear on the stem of the plant The States.[14] Race strains have a more limited host range vascular system will exhibit a progressively darker brown progresses, in addition to possible lethan race 1, and are mostly restricted to tropical envi- color as the disease[18] sions on the stem Management practices are similar ronments Race strains are more cold tolerant than the for those of potato other two and are found in tropical highlands and temperate areas.[14] The host range for race biovar includes potatoes, tomatoes, and geraniums Race biovar is very common throughout the world, but is not generally 5.5 Banana reported in North America,[15] and is therefore the focus of many sanitation and quarantine management practices Typically yellowing and wilting of older leaves, as well as reduced fruit size and eventual rotting of the fruit.[19] to prevent the introduction or spread of the pathogen In addition flowers can become blackened and shriveled, and the vascular tissue discolored.[20] Exclusion of the disease where it is not present is the only effective means Management of control If an area does become infected all of the infected plants must be eliminated, which is why strong 5.1 General management sanitation practices must be used to reduce the spread of disease.[20] Commercial chemicals have generally proven to be ineffective in controlling the pathogen and are not recommended as a means of control.[1] In regions where the pathogen is endemic a strategy of integrated disease man- Importance agement (IDM) is the best strategy to reduce any impact of the pathogen Using pathogen-free planting materi- Ralstonia solanacearum is classified as one of the world’s als is a necessity Planting resistant cultivars minimizes most important phytopathogenic bacteria due to its lethalthe ill effects of the pathogen, although there are cur- ity, persistence, wide host range and broad geographic rently no completely immune cultivars available Finally, distribution Although the pathogen causes major yield lost in the tropics and subtropics, it is currently a continuing threat in temperate climates.[1] Ralstonia solanacearum is a high profile alien plant pathogen of A2 Quarantine status affecting a very wide range of crops This means that it is present in parts of Europe but is under statutory control Worldwide, the most important crops affected are: Potato, Tomato, Tobacco, Banana and Geranium In the UK and the rest of the EU the most important crops affected are Potato and Tomato It would cause serious economic damage were it to become more established than it currently is Losses are due to actual yield reduction and also due to statutary measures taken to eliminate the disease REFERENCES [5] Paret, M.L., de Silva, A.S., Criley, R.A and Alvarez, A.M 2008 Ralstonia solanacearum Race 4:Risk Assessment for Edible Ginger HortTechnology 18:90-96 [6] Terblanche, J.; de Villiers, D.A (2013) Prior, Philippe; Allen, Caitilyn; Elphinstone, John, eds Bacterial Wilt Disease: Molecular and Ecological Aspects (1st ed.) Paris: Springer Science & Business Media p 326 ISBN 9783662035924 [7] “Bacterial Wilt- Ralstonia solanacearum race biovar 2” Massnrc.org 2008-02-25 Retrieved 2012-09-24 [8] Vasse, J; Genin, S.; Pascal, F.; Boucher, C.; Brito, B (2000) “The hrpB and hrpG Regulatory Genes of Ralstonia solanacearum Are Required for Different Stages of the Tomato Root Infection Process” Molecular PlantMicrobe interactions 13 (3): 259–267 Bacterial wilt caused by R solanacearum is of economic importance because it infects over 250 plant species in over 50 families It causes a wilt disease in several important agricultural crops such as potato, tomato, to- [9] Angot, Aurelie; Peeters, N; Lechner, E; Vailleu, F; Baud, C; Gentzbittel, L; Sartorel, E; Genschik, P; Boucher, C; bacco, banana, pepper and eggplant The disease is Genin, Stephane (2006) “Ralstonia solanacearum reknown as Southern wilt, bacterial wilt, and brown rot of quires F-box-like domain-containing type III effectors potato Many more dicots suffer from the disease than to promote disease on several host plants” Proceedings monocots Among the monocot host, the order Zingibof the National Academy of Sciences 103 (39): 14620– erales dominates with over families being infected by 14625 doi:10.1073/pnas.0509393103 [1] this bacterium The reason why some families are more susceptible to bacterial wilt is still unknown Originally, [10] Remenant, Benoit; Coupat-Goutaland, B.; Guidot, A.; Ralstonia solanacearum is found in tropical, sub-tropical Cellier, G.; Prior, P (2010) “Genomes of three tomato pathogens within the Ralstonia solanacearum and warm temperate climates, but is not believed to surspecies complex reveal significant evolutionary divervive cold temperatures However, this pathogen has regence” BMC Genomics 11 (1): 379 doi:10.1186/1471cently been detected in geraniums (Pelargonium spp.) in 2164-11-379 PMC 2900269 PMID 20550686 Wisconsin, USA [21] and was traced back to the import of geranium cuttings to North America and Europe from [11] Poueymiro, M and S Genin 2009 Secreted proteins the highland tropics where race biovar is endemic [22] from Ralstonia solanacearum: a hundred tricks to kill a plant Current Opinion in Microbiology 12: 44-52 Brown rot of potato caused by Ralstonia solanacearum race biovar is among the most serious disease of [12] Genin, S and C Boucher 2004 Lessons learned from potato worldwide, which is responsible for an estimated the genome analysis of Ralstonia solanacearum Annual [23] $950 million in losses each year Race biovar is Review of Phytopathology 42:107-134 [22] cold tolerant and classified as a quarantine pathogen In addition, this race/biovar has been listed as a Select [13] Heuer, H.; Yin, Y -N.; Xue, Q -Y.; Smalla, K.; Guo, J -H (2007) “Repeat Domain Diversity of avrBs3Agent in the Agriculture Bioterrorism Act of 2002 and is Like Genes in Ralstonia solanacearum Strains and Asconsidered to have potential to be developed as a biotersociation with Host Preferences in the Field” Applied rorist weapon.[21] References [1] Denny T., “Plant Pathogenic Ralstonia species” in GNANAMANICKAM, S S (2006) Plant-associated bacteria Dordrecht, Springer pp 1-62 [2] Agrios, G N (2008) Plant pathology Amsterdam [u.a.], Elsevier Academic Press, pp 647-649 [3] “Ralstonia solanacearum” Bioinfo.genopoletoulouse.prd.fr Retrieved 2012-09-24 [4] Andersona R C and Gardner D E 1999 An Evaluation of the Wilt-Causing Bacterium Ralstonia solanacearum as a Potential Biological Control Agent for the Alien Kahili Ginger (Hedychium gardnerianum) in Hawaiian Forests Biological Control 15 (2): 89-96 and Environmental Microbiology 73 (13): 4379–4384 doi:10.1128/AEM.00367-07 PMC 1932761 PMID 17468277 [14] “R solanacearum/Bacterial wilt - Brown rot of potato” Plantpath.ifas.ufl.edu 2008-09-12 Retrieved 2012-0924 [15] http://www.aphis.usda.gov/plant_health/plant_pest_ info/ralstonia/downloads/rasltoniaactionplanv4web.pdf [16] “Potato brown rot symptoms” Cals.ncsu.edu Retrieved 2012-09-24 [17] http://www.aphis.usda.gov/plant_health/plant_pest_ info/ralstonia/downloads/ralstoniadatasheet_CPHST pdf [18] “Tomato bacterial wilt symptoms” Cals.ncsu.edu Retrieved 2012-09-24 5 [19] “Banana Moko disease symptoms” Cals.ncsu.edu Retrieved 2012-09-24 [20] http://www.agric.wa.gov.au/objtwr/imported_assets/ content/pw/ph/dis/fn/fs2006_moko_neyres.pdf [21] Hudelson B 2005 University of Wisconsin Pest Alert Ralstonia wilt [22] Milling A., Meng F., Denny T., Allen C 2009 Interactions with hosts at cool temperatures, not cold tolerance, explain the unique epidemiology of Ralstonia solanacearum race biovar [23] Ephinstone, J G 2005 The current bacterial wilt situation: a global overview pp 9-28 in: Bacterial Wilt: The Disease and the Ralstonia solanacearum Species Complex C Allen, P Prior, and A C Hayward, eds American Phytopathological Society, St Paul, MN External links • Species Profile- Southern Bacterial Wilt (Ralstonia solanacearum), National Invasive Species Information Center, United States National Agricultural Library Lists general information and resources for Southern Bacterial Wilt • http://www.bacterio.cict.fr/qr/ralstonia.html • Confirmation of export licence required • List of Plant Pathogens subject to Export Control TEXT AND IMAGE SOURCES, CONTRIBUTORS, AND LICENSES Text and image sources, contributors, and licenses 9.1 Text • Ralstonia solanacearum Source: https://en.wikipedia.org/wiki/Ralstonia_solanacearum?oldid=720762845 Contributors: Onco p53, Rich Farmbrough, Woohookitty, BD2412, Rjwilmsi, Fish and karate, Chris the speller, Eliyak, Fredvries, Drinibot, Cydebot, PKT, Smartse, Million Moments, Somanypeople, Ninjatacoshell, Doc James, Pseudomonad, Matthew Yeager, Jboltonnal, SchreiberBike, El bot de la dieta, DumZiBoT, Ost316, Addbot, Flakinho, Yobot, Xqbot, TechBot, DSisyphBot, Jvh100, ScienceGeekling, Tim1357, RjwilmsiBot, ClueBot NG, Tuantran2904, Action Scientist, Ccevo2010, NotWith, Ccevo2011, Hsp90, Dexbot, ThunderSkunk, Me, Myself, and I are Here, Xanthi950, Monkbot, Roshanpakka, AnnaVetci and Anonymous: 12 9.2 Images • File:Ralstonis_wilt_symptom.jpg Source: https://upload.wikimedia.org/wikipedia/commons/9/9a/Ralstonis_wilt_symptom.jpg License: Public domain Contributors: USDA Forest Service, http://www.forestryimages.org/browse/detail.cfm?imgnum=1234078 Original artist: Clemson University - USDA Cooperative Extension Slide Series 9.3 Content license • Creative Commons Attribution-Share Alike 3.0 ... Wilt- Ralstonia solanacearum race biovar 2” Massnrc.org 200 8-0 2-2 5 Retrieved 201 2-0 9-2 4 [8] Vasse, J; Genin, S.; Pascal, F.; Boucher, C.; Brito, B (2000) “The hrpB and hrpG Regulatory Genes of Ralstonia. .. 64 7-6 49 [3] ? ?Ralstonia solanacearum? ?? Bioinfo.genopoletoulouse.prd.fr Retrieved 201 2-0 9-2 4 [4] Andersona R C and Gardner D E 1999 An Evaluation of the Wilt-Causing Bacterium Ralstonia solanacearum. .. Benoit; Coupat-Goutaland, B.; Guidot, A.; Ralstonia solanacearum is found in tropical, sub-tropical Cellier, G.; Prior, P (2010) “Genomes of three tomato pathogens within the Ralstonia solanacearum