1 Ralstonia solanacearum Raza 3 biovar 2

2 Ralstonia solanacearum Raza 3 biovar 2Introducción Hospedantes Síntomas Transmisión Detección Control

3 Introduction Ralstonia solanacearum Raza 3 biovar 2 es una bacteria que causa las siguientes enfermedades: Pudrición marrón y marchitez bacteriana de la papa Marchitez sureña del geranio Marchitez bacteriana del tomate y otras solanáceas Este patógeno está considerado como un miembro de la lista de agentes seleccionados de bioterrorismo agrícola. Ralstonia solanacearum Race 3 biovar 2 is a bacterium that causes the following diseases: Southern Wilt of Geranium Brown Rot or of Potato Bacterial Wilt of Tomato and other Solanaceous crops R. solanacearum Race 3 biovar 2 is considered to be a select agent by the United States under the Agricultural Bioterrorism Protection Act of 2002 because it has the potential to be a severe threat and does not naturally occur in the U.S.

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5 Other Ralstonia solanacearum Races and BiovarsRaza Rango de hospedantes Distribución geográfica Biovar 1 Amplio Asia, Australia, Americas 3,4 2 Banana Otras Musa spp. Caribe, Brasil Filipinas 3 Papa, algunas otras solanáceas, geranio; Mundial, excepto US y Canadáa 4 Gengibre Asia 5 Frutillas China It is important to note that there are other races and biovars of Ralstonia solanacearum. Only R. solanacearum Race 3 biovar 2 is on the select agent list. In total, five races of R. solanacearum have been described with differences in host range. Race 1 can infect hundreds of different plant species in 50 families and Race 1 biovar 1 is endemic in the Southern United States where it is commonly found on tomato, tobacco and other crops. (Harris, 1972; Denny and Hayward, 2001). Races 2, 4, and 5 occur outside the U.S. in warm regions and are not considered a threat due to their poor cold-temperature tolerance. Race 3 is commonly found through out the world except in the U.S. and Canada. The race/biovar of most concern to the U.S. is Race 3 biovar 2, because of its ability to cause damage to potato, tomato, eggplant and geraniums in cooler climates than Race 1. The potato industries in both the United States and Canada are concerned with potential introduction of Race 3 because potato crops in other temperate countries have experienced serious disease problems due to the cold temperature tolerance of Race 3 (Kim et al 2003 and Daughtrey 2003). In the U.S., especially in the south, it is important to be able to discern through diagnosis Race 1 and Race 3 because they can have a number of the same hosts and symptoms. (Daughtrey, 2003 Reprinted, with slight modification, from Denny and Hayward, 2001)

6 Ralstonia solanacearum.It is important to note that there are other races and biovars of Ralstonia solanacearum. Only R. solanacearum Race 3 biovar 2 is on the select agent list. Race 1 can infect hundreds of different plant species in 50 families and Race 1 biovar 1 is endemic in the Southern United States where it is commonly found on tomato, tobacco and other crops. Races 2, 4, and 5 occur outside the U.S. in warm regions and are not considered a threat due to their poor cold-temperature tolerance. Race 3 is commonly found through out the world except in the U.S. and Canada. The race/biovar of most concern to the U.S. is Race 3 biovar 2, because of its ability to cause damage to potato, tomato, eggplant and geraniums in cooler climates than Race 1. The potato industries in both the United States and Canada are concerned with potential introduction of Race 3 because potato crops in other temperate countries have experienced serious disease problems due to the cold temperature tolerance of Race 3.

7 Global Distribution Las pérdidas alrededor del mundo por la marchitez bacteriana de la papa son más de $950 millones por año (Allen 2003). La resurgencia de R. solanacearum Raza 3 biovar 2 se han presentado en todo Europa en los últimos años. Esta resurgencia se debe a la importación de material vegetal infectado de lugares donde la enfermedad está de tiempo establecida (Janse 1996). World wide losses from bacterial wilt on potato crops are more than $950 million per year (Allen 2003). Outbreaks of R. solanacearum Race 3 biovar 2 have occurred throughout Europe in recent years. These outbreaks are thought to be the result of imports of infected plant material from locations where the disease is already established (Janse 1996). Photo H.D. Thurston, Cornell University,

8 Hospedantes Los hospedantes de Ralstonia solanacearum Raza 3 biovar 2 incluyen varias solanáceas: papa tomate Berengena El geranio (Pelargonium spp.) puede también servir coomo hospèdante. The plant pathogenic bacterium known as Ralstonia solanacearum R3b2 has a smaller host range than Race 1. The host plants of concern in the United States include geraniums and solanaceous plants: potato, tomato and eggplant In addition, weeds and semi-aquatic plants could be a potential host for Ralstonia solanacearum Race 3. Photo H.D. Thurston, Cornell University,

9 Signos y síntomas en plantas de papaFollaje Enanismo Amarillamiento Marchitez, inicialmente limitada al ápice de la planta. Tallo Lesiones vasculares Colapso de plantas jóvenes Exudados bacterianos Foliage Foliage of potatoes infected with R. solanacearum may show stunting, yellowing, and wilting. Early in the infection wilting leaves may be limited to the top portion of the plant. The plants can appear to recover at night, but soon wilting is irreversible and death of the plant follows. Stems The stems of young plants may collapse and/or have narrow dark streaking present. Vascular discoloration of the stem appears to be grey or brown and bacterial ooze is present. Again, upon placing cut stem material in a test tube with water, bacterial streaming may occur from the vascular tissue (Kluepfel et al. and Elphinstone 2004). Photos H. David Thurston, Cornell University,

10 Signos y síntomas en tubérculos de papaLesiones en el anillo vascular Exudado bacteriano, el cual en estados posteriores puede emerger de los “ojos” y “yemas”. Photo Plant Protection Service Archives, Netherlands, Bacterial Ooze Tuber Symptomatic potato tubers will show discoloration of the vascular ring. Initially the vascular ring appears yellow to light brown, but as the infection progresses the ring will become browner. Bacterial ooze may also be present; in later stages this ooze may emerge from the eyes and heel (stolon) end to which soil particles will attach. Photo Central Science Laboratory, Harpenden Archives, British Crown, United Kingdom,

11 Signos y síntomas en plantas de tomateMarchitez Lesiones vasculares Exudación bacteriana Vascular Discoloration Important Note: The photos on this slide depict symptoms of R. solanacearum Race 1. These images are on this slide because symptoms of Race 1 are similar to Race 3. Tomato plants infected with R. solanacearum Race 3 biovar 2 initially show a reduction in the firmness of young leaves. Upon further development the plant will wilt on one or both sides during conditions favorable to the pathogen which include saturated humidity and warm soil temperatures around 25 C (77 F). When the temperature is below 21 C (70 F) the environment is less favorable for the pathogen and excess roots may develop along the stem. Brown discoloration of the vascular tissue as well as bacterial ooze may be present. Vascular Discoloration Photos Clemson University - USDA Cooperative Extension Slide Series,

12 Síntomas en geranio Amarillamiento, marchitex y necrosis de hojas inferiores Lesiones vasculares y necrosis del tallo. Pudrición marrón de raíces The lower leaves of plants infected by R. solanacearum Race 3 biovar 2 may show yellowing, wilting, and browning. Another common symptom is vascular discoloration of the stem. Roots may also show a brown discoloration. Photos Margery Daughtrey, Cornell University,

13 Signos en geranio Exudación bacterianaExudado bacteriano Exudación bacteriana Flujo bactgeriano: El tallo o peciolo cortado colocado en agua, produciría una nube generada por el flujo bacteriano fuera del tejido vegetal. Photo Margery Daughtrey, Cornell University, Flujo bacteriano Bacterial ooze and bacterial streaming both represent signs of the pathogen. Bacterial ooze can be observed in cut stems. If the petioles of infected leaves are removed, cut up, and placed in a water-filled test tube the water will become cloudy as the bacteria stream out of the xylem into the water. Photo David B. Langston, University of Georgia,

14 Transmisión Suelo contaminado, agua de irrigación, agua superficial, equipo y personal. El patógeno puede entrar a las plantas vía heridas ocasionadas por la manipulación o alimentación por nematodos. R. solanacearum Race 3 biovar 2 is a soilborne pathogen that primarily infects hosts through the roots. Plants may be infected through wounds caused by handling or nematode feeding or by openings occurring during normal root development. Crops susceptible to the disease may become infected when grown in contaminated soils or when they are irrigated with contaminated water (Janse 1996). In greenhouse operations, subirrigation systems could be a means for disseminating the pathogen. Photo Anson Eaglin, USDA-APHIS ,

15 Transmisión Material vegetal infectadoEn papa: la diseminación es a través de semilla de papa infectada. En geranios: la diseminación es a través de el uso de esquejes infectados. R. solanacearum Race 3 biovar 2 can also be spread through the use of infected plant material. This was what was witnessed in the U.S. with the geranium industry. The disease was introduced into greenhouses through the use of infected plant cuttings. For potatoes, the disease can be spread by the use of infected potato seed stock. (Lemay et al. 2003) Photo by Peggy Greb, USDA-ARS,

16 Cultivo de R. solanacearum sobre el medio semi-selective TZCDetección y Diagnosis El diagnóstico a nivel de raza y biovar puede ser difícil, y frecuentemente requiere varias pruebas de diagnóstico para hacer un diagnóstico final. Cultivo de R. solanacearum sobre el medio semi-selective TZC Aislamiento sobre medios semi-selectivos. El uso de medios selectivos para R. solanacearum, no para raza o biovar ELISA Especifico para Ralstonia solanacearum, no para raza y biovar Usada para selección inicial de grandes cantidades de material. The diagnosis to Race and biovar can be difficult requiring the use of several diagnostic tests to make a final diagnosis. Semi-selective media, ELISA and Immunostrips are only specific to genus and species and not Race and biovar. Therefore they are useful as a first step in the diagnostic process. ELISA can be extremely useful for screening large quantities of materials. Immunostrips which is an ELISA based technology can be used in the field. Photo Tom Creswell, NCSU ,

17 Detección y Diagnosis Prueba para determinar Raza y BiovarPrueba de utilización de carbono (usado para diferenciar biovar) PCR a tiempo real (usada para diferenciar razas) Definitive identification of R. solanacearum Race 3 biovar 2 requires at least two tests.  Biovar is determined by using an assay that measures acid generation from a panel of sugars and sugar alcohols.  Race 3 of R. solanacearum may be identified with a PCR reaction containing reagents specific for Race 3. Real-time PCR used for determination of race of R. solanacearum. (Photo Dawn Dailey-O’brien, Cornell University)

18 Control: Papa Variedades resistentesEl control químico no es efectivo. Eliminación de malezas solanáceas hospedantes que puedan servir como reservorios de inóculo. Selección de tubérculos libres de la enfermedad antes de plantarlos en campo. Rotación con cultivos no susceptibles. Currently there are no chemical controls available. Some methods of control include: eradication of weedy hosts, altering soil pH over the growing season and screening tubers for disease before planting. Woody nightshade (Solanum dulcamara) which commonly grows along riverbanks in the UK can serve as a reservoir of inoculum. These plants are thought to have been the source of contamination for potato crops irrigated with river water in some cases (Plant Health Division 2002 and Elphinstone and Harris 2002). A variety of control measures are being utilized in Europe for potato crops including lowering soil pH in the summer and raising it again in the fall, treating waterways to remove woody nightshade, and using non-susceptible crops for rotations (Lemay et al. 2003). Malezas solanáceas pueden servir como hospedantes de R. solanacearum Raza 3 Biovar 2 y fuente de inóculo para el cultivo de papa. Photo Joel Floyd, USDA APHIS PPQ,

19 Control: Tomate Químicos derivados de plantas: El Thymol ha sido usado como un fumigante de suelo pre plantación con bastante éxito (Momol 2006). Los esfuerzos de los fitomejoradores han resultado en algunas progenies de tomate con alta resistencia pero también con cualidades indeseables como frutos pequeños (Momol 2006). Control on tomato relies on cultural practices including the use of resistant varieties. Plant derived volatile compound thymol was found to reduce bacterial wilt incidence of tomato when used as a pre-plant soil fumigant. However, it’s effectiveness post-infection has not been determined (Momol 2006) . Plant breeding efforts have resulted in some tomato breeds such as Hawaii 7996 with high resistance but also some undesirable traits like small fruit. There are some large fruit varieties with moderate resistance to bacterial wilt caused by Race 1 (Momol 2006) . Photo Keith Weller, USDA-ARS,

20 References Allen, C Bacterial Wilt Disease & Ralstonia solanacearum. Talk from 2003 Ralstonia Solanacearum race 3 biovar 2 Outbreak in Geraniums: A Program Review meeting held June 17 and 18, 2003 in Riverdale, MD. Daughtrey, M New and Re-emerging Diseases in Department of Plant Pathology, Cornell University, Long Island Horticultural Research & Extension Center. Denny, T. P. and Hayward, A.C Ralstonia, pages in: Schaad, N. W. et al. Laboratory guide for the identification of plant pathogenic bacteria, 3rd ed. APS Press, St. Paul, 373 pp. Elphinstone, J. and Harris, R Monitoring and control of the potato brown rot bacterium in irrigation water. British Potato Council report Accessed 2004 January 8. Elphinstone, J. January Personal communication. EC project number: SMT project CT Harris, D. C Intra-specific variation in Pseudomonas solanacearum. Pages in: Proc. Int. Conf. Plant Pathog. Bact., 3rd. Janse, J Potato Brown rot in western Europe – history, present occurrence and some remarks on possible origin, epidemiology and control strategies. Bulletin OEPP/EPPO 26: Kim, S. H., Olson, R. N. and Schaad, N Ralstonia solanacearum Biovar 2, Race 3 in geraniums imported from Guatemala to Pennsylvania in Plant Disease 92:S42. Kim, S. H., T. N. Olson, N. W. Schaad, and G. W. Moorman Ralstonia solanacearum Race 3, Biovar 2, the Causal Agent of Brown Rot of Potato, Identified in Geraniums in Pennsylvania, Delaware, and Connecticut. Plant Disease Page 87:4. Lemay, A., Redlin, S., Fowler, G., Dirani, M. 2003, February 12. Pest Data Sheet Ralstonia solanacearum race 3 biovar 2. USDA/APHIS/PPQ Center for Plant Health Science and Technology Plant Epidemiology and Risk Analysis Laboratory Raleigh, NC. Momol, T. 2006, October 12. Recovery Plan for Ralstonia solanacearum Race 3 biovar 2, Causing Brown Rot of Potato, Bacterial Wilt of Tomato and Southern Wilt of Geranium. National Plant Disease Recovery System. Accessed 2006 October 17. O’Hern, C January 5. Detection of Ralstonia solanacearum race 3 biovar 2 in New York Greenhouse (document by Richard Dunkle) [Distribution list]. Accessed 2004 January 5. USDA-ARS Plant Health Division Potato Brown Rot (RALSTONIA SOLANACEARUM) Report on monitoring and eradication in England Defra, Plant Health Division. Accessed 2004 January 8. Williamson, L., Nakoho, K., Hudelson, B. and Allen, C Ralstonia solanacearum race 3, biovar 2 strains isolated from geranium are pathogenic on potato. Plant Dis. 86: