Xylella fastidiosa
Xylella fastidiosa | |
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Scientific classification | |
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Genus: | Xylella |
Species: | X. fastidiosa
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Binomial name | |
Xylella fastidiosa Wells et al., 1987
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Xylella fastidiosa is an aerobic,
Xylella fastidiosa can infect an extremely wide range of plants, many of which do not show any symptoms of disease.
Pathogen anatomy and disease cycle
Xylella fastidiosa is rod-shaped, and at least one subspecies has two types of pili on only one pole; longer, type IV pili are used for locomotion, while shorter, type I pili assist in biofilm formation inside their hosts. As demonstrated using a PD-related strain, the bacterium has a characteristic twitching motion that enables groups of bacteria to travel upstream against heavy flow, such as that found in xylem vessels.[17] It is obligately insect-vector transmitted from xylem-feeding insects directly into xylem, but infected plant material for vegetative propagation (e.g. grafting) can produce mature plants that also have an X. fastidiosa disease.[18] In the wild, infections tend to occur during warmer seasons, when insect vector populations peak. The bacterium is not seed transmitted, but instead is transmitted through "xylem feed-ing, suctorial homopteran insects such as sharpshooter leafhoppers and spittle bugs"[19] and has been historically difficult to culture (fastidious),[20][21] as its specific epithet, fastidiosa, reflects.
X. fastidiosa can be divided into four subspecies that affect different plants and have separate origins. X. fastidiosa subsp. fastidiosa is the most studied subspecies, as it is the causal agent of PD; it is thought to have originated in southern Central America, and also affects other species of plants. X. f. multiplex affects many trees, including stone-fruit ones such as peaches and plums, and is thought to originate in temperate and southern North America. X. f. pauca is believed to have originated in South America. It is the causal agent of citrus variegated chlorosis (CVC) in Brazil[22] and also affects South American coffee crops, causing coffee leaf scorch. X. f. sandyi is thought to have originated in the southern part of the United States, and is notable for causing oleander leaf scorch.[23]
X. fastidiosa has a two-part lifecycle, which occurs inside an insect vector and inside a susceptible plant. While the bacterium has been found across the globe, only once the bacterium reaches systemic levels do symptoms present themselves. Once established in a new region, X. fastidiosa spread is dependent on the obligate transmission by xylem-sap feeding insect.[24] Within susceptible plant hosts, X. fastidiosa forms a biofilm-like layer within xylem cells and tracheary elements that can completely block the water transport in affected vessels.[25]
Strains
EB92-1 is a nonpathogenic
Symptoms
Significant variation in symptoms is seen between diseases, though some symptoms are expressed across species. On a macroscopic scale, plants infected with a X. fastidiosa-related disease exhibit symptoms of water, zinc, and iron deficiencies,[27] manifesting as leaf scorching and stunting in leaves turning them yellowish-brown, gummy substance around leaves,[27] fruit reduction in size and quality,[27] and overall plant height. As the bacterium progressively colonizes xylem tissues, affected plants often block off their xylem tissue, which can limit the spread of this pathogen; blocking can occur in the form of polysaccharide-rich gels, tyloses, or both. These plant defenses do not seem to hinder the movement of X. fastidiosa. Occlusion of vascular tissue, while a normal plant response to infection, makes symptoms significantly worse; as the bacterium itself also reduces vascular function, a 90% reduction of vascular hydraulic function was seen in susceptible Vitis vinifera.[28] This bacterium rarely completely blocks vascular tissue. There usually is a slight amount of vascular function that keeps the plant alive, but makes its fruit or branches die, making the specific plant economically nonproductive. This can cause a massive drop on supply of quality fruit.[27] Smaller colonies usually occur throughout a high proportion of xylem vessels of a symptomatic plant.[citation needed]
X. fastidiosa is a Gram-negative, xylem-limited illness that is spread by insects. It can damage a variety of broadleaved tree species that are commonly grown in the United States. X. fastidiosa can be found in about 600 different plant species.[citation needed]
- Withering and desiccation of branches
- Leaf chlorosis
- Dwarfing or lack of growth of the plant
- Drooping appearance and shorter internodes
- Shriveled fruits on infected plants
- Premature fruit abscission
- gum-like substance on leave
- hardening and size reduction of fruit
Pierce's disease
Severe PD symptoms include shriveled fruit, leaf scorching, and premature abscission of leaves, with bare petioles remaining on stems.[29]
Citrus variegated chlorosis
This disease is named after the characteristic spotty chlorosis on upper sides of citrus leaves. Fruits of infected plants are small and hard.[8]
Leaf scorches
In
Environment
X. fastidiosa occurs worldwide, though its diseases are most prominent in riparian habitats including the southeastern United States, California, and South America.
Symptoms of X. fastidiosa diseases worsen during hot, dry periods in the summer; lack of water and maximum demand from a full canopy of leaves, combined with symptoms due to disease, stress infected plants to a breaking point. Cold winters can limit the spread of the disease,[21] as it occurs in California, but not in regions with milder winters such as Brazil. Additionally, dry summers seem to delay symptom development of PD in California.[18]
Any conditions that increase vector populations can increase disease incidence, such as
Alexander Purcell, an expert on X. fastidiosa, hypothesized that plants foreign to X. fastidiosa's area of origin, the neotropical regions, are more susceptible to symptom development. Thus, plants from warmer climates are more resistant to X. fastidiosa disease development, while plants from areas with harsher winters, such as grapes, are more severely affected by this disease.[21]
Host species
X. fastidiosa has a very wide host range; as of 2020, its known host range was 595 plant species, with 343 species confirmed by two different detection methods, in 85 botanical families.
Due to the temperate climates of South America and the southeastern and west coast of the United States, X. fastidiosa can be a limiting factor in fruit crop production, particularly for
X. fastidiosa also colonizes the foreguts of insect vectors, which can be any xylem-feeding insects, often sharpshooters in the Cicadellidae subfamily Cicadellinae.[3][21] After an insect acquires X. fastidiosa, it has a short latent period around 2 hours, then the bacterium is transmissible for a period of a few months or as long as the insect is alive.[citation needed] The bacterium multiplies within its vectors, forming a "bacterial carpet" within the foregut of its host. If the host sheds its foregut during molting, the vector is no longer infected, but can reacquire the pathogen. At present, no evidence shows that the bacterium has any detrimental effect on its insect hosts.
Oleander
Oleander leaf scorch is a disease of landscape
Both almond and oleander plants in the Italian region of Apulia have also tested positive for the pathogen.[35]
Grape vines
Pierce's disease (PD) was discovered in 1892
Symptoms of infection on grape vines
When a grape vine becomes infected, the bacterium causes a gel to form in the xylem tissue of the vine, preventing water from being drawn through the vine.
Collaborative efforts for solutions
In a unique effort, growers, administrators, policy makers, and researchers are working on a solution for this immense X. fastidiosa threat. No cure has been found,[41] but the understanding of X. fastidiosa and glassy-winged sharpshooter biology has markedly increased since 2000, when the California Department of Food and Agriculture, in collaboration with different universities, such as University of California, Davis; University of California, Berkeley; University of California, Riverside, and University of Houston–Downtown started to focus their research on this pest. The research explores the different aspects of the disease propagation from the vector to the host plant and within the host plant, to the impact of the disease on California's economy. All researchers working on Pierce's disease meet annually in San Diego in mid-December to discuss the progress in their field. All proceedings from this symposium can be found on the Pierce's disease website,[42] developed and managed by the Public Intellectual Property Resource for Agriculture (PIPRA).[43]
Few resistant Vitis vinifera varieties are known, and
A resistant variety, 'Victoria Red', was released for use especially in Coastal Texas.[47]
Olive trees
![](http://upload.wikimedia.org/wikipedia/commons/thumb/7/79/Olivenhain_mit_Xylella_fastidiosa_bei_Surano_LE_190710.jpg/220px-Olivenhain_mit_Xylella_fastidiosa_bei_Surano_LE_190710.jpg)
In October 2013, the bacterium was found infecting olive trees in the region of Apulia in southern Italy.[35] The disease caused rapid decline in olive grove yields, and by April 2015, was affecting the whole Province of Lecce and other zones of Apulia,[7][48] though it had not previously been confirmed in Europe.[49] The subspecies involved in Italy is X. f. pauca, which shows a marked preference for olive trees and warm conditions and is thought to be unlikely to spread to Northern Europe.[50]
The cycle in olives has been called olive quick decline syndrome (in Italian: complesso del disseccamento rapido dell'olivo).[49][51] The disease causes withering and desiccation of terminal shoots, distributed randomly at first but then expanding to the rest of the canopy[51] resulting in the collapse and death of trees.[51] In affected groves, all plants normally show symptoms.[51] The most severely affected olives are the century-old trees of local cultivars Cellina di Nardò and Ogliarola salentina.[52]
By 2015, the disease had infected up to a million olive trees in Apulia [53] and Xylella fastidiosa had reached Corsica,[54] By October 2015, it had reached Mainland France, near Nice, in Provence-Alpes-Côte d'Azur, affecting the non-native myrtle-leaf milkwort (Polygala myrtifolia). This is the subspecies X. fastidiosa subsp. multiplex which is considered to be a different genetic variant of the bacterium to that found in Italy.[55][56] On 18 August 2016 in Corsica, 279 foci of the infection have been detected, concentrated mostly in the south and the west of the island.[57] In August 2016, the bacterium was detected in Germany in an oleander plant.[58] In January 2017 it was detected in Mallorca and Ibiza.[59]
Notably, in 2016,
In June 2017, it was detected in the
Citrus
Xylella infection was detected in South American citrus in the 1980s and subsequently in the USA but had limited spread beyond the America's until the detection in citrus groves in Portugal in 2023.[64]
Genome sequencing
The genome of X. fastidiosa was sequenced by a pool of over 30 research laboratories in the state of
See also
- Bacterial leaf scorch
- Homalodisca vitripennis
- Philaenus spumarius
References
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- ^ a b "Minimizing the Spread of Disease in Italy's Famous Olive Trees". Our Environment at Berkeley. University of California, Berkeley, Department of Environmental Science, Policy, and Management (ESPM). 9 February 2015. Retrieved 5 May 2015.
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- ^ a b c Mizell, Russell F.; Andersen; Tipping (January 2003). "Xylella Fastidiosa Diseases and Their Leafhopper Vectors" (PDF). University of Florida IFAS Extension. Archived from the original (PDF) on 25 February 2021. Retrieved 30 November 2017.
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- Gross, Dennis C.; Lichens-Park, Ann; Kole, Chittaranjan, eds. (2014). Genomics of plant-associated bacteria. Heidelberg. pp. x+278. S2CID 7068164.
- Gross, Dennis C.; Lichens-Park, Ann; Kole, Chittaranjan, eds. (2014). Genomics of plant-associated bacteria. Heidelberg. pp. x+278.
- ^ a b c d Almedia, Rodrigo (2013). "Xylella Fastidiosa".
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- Delbianco, Alice; Gibin, Davide; Pasinato, Luca; Morelli, Massimiliano (2021). "Update of the Xylella spp. host plant database – systematic literature search up to 31 December 2020". S2CID 199641165.
- Delbianco, Alice; Gibin, Davide; Pasinato, Luca; Morelli, Massimiliano (2021). "Update of the Xylella spp. host plant database – systematic literature search up to 31 December 2020".
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- ^ a b Kinver, Mark (9 January 2015). "'Major consequences' if olive disease spreads across EU". BBC News. Retrieved 1 March 2015.
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- ^ Meyer, Brittnay (2018). "Pierce's Disease on grapes". Texas Plant Disease Diagnostic Lab. Retrieved 5 May 2023.
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- ^ a b c winepros.com.au. Oxford Companion to Wine. "Pierce's disease". Archived from the original on 8 August 2008. Retrieved 7 May 2008.
- ^ PIPRA Pierce's Disease website. "Pierce's disease".
- ^ "Public Intellectual Property Resource for Agriculture (PIPRA)". Archived from the original on 5 March 2016.
- ^ Jiménez A., L.G. (July–September 1985). "Evidencia inmunológica del mal de pierce de la vid en Venezuela". Turrialba. 35 (3): 243–247.
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- ^ PD/GWSS Board bulletin Archived 2015-05-18 at the Wayback Machine, California Department of Food & Agriculture, Spring 2007 (p. 2)
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- ^ Spagnolo, Chiara (29 April 2015). "Xylella, allarme nuovi focolai, per la Ue interessata tutta la Puglia" [Xylella, new outbreak alarm, for the EU all of Puglia affected]. La Repubblica (in Italian). Retrieved 8 May 2015.
- ^ a b "First report of Xylella fastidiosa in the EPPO region". European and Mediterranean Plant Protection Organization (EPPO). Retrieved 1 March 2015.
- ^ "Xylella fastidiosa". Plant Health Portal. Department for Environment, Food and Rural Affairs. Retrieved 24 June 2017.
- ^ a b c d Butler, Julie (29 March 2014). "Expert Says Eradication of New Olive Tree Disease in Europe Unlikely". Olive Oil Times. Retrieved 1 March 2015.
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- ^ Squires, Nick (27 February 2015). "Italy warns deadly olive tree bacteria could spread across Europe". The Telegraph. Retrieved 1 March 2015.
- ^ "Olive oil dries up". The Economist. 31 July 2015. Retrieved 31 July 2015.
- ^ "Xylella fastidiosa". Plants. European Commission. 17 October 2016. Retrieved 24 June 2017.
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- ^ "Xylella : carte et liste des communes en zones délimitées en Corse au 18 août 2016". Direction régionale de l'alimentation, de l'agriculture et de la forêt de Corse (in French). Archived from the original on 23 August 2016. Retrieved 23 August 2016.
- ^ Schröder, Elke. "Pflanzen-Killerbakterium: Teile von Zeulenroda-Triebes zur Sperrzone erklärt" [Plant killer bacteria: Parts of Zeulenroda rails declared a restrict zone]. Antenne Thueringen (in German). Archived from the original on 27 August 2016. Retrieved 23 August 2016.
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Further reading
- "CDFA - Pierce's Disease Research Updates". piercesdisease.cdfa.ca.gov. Retrieved 15 February 2020.
- "Glassy-winged Sharpshooter and Pierce's Disease in California". December 2002. Archived from the original on 9 May 2006. Retrieved 15 February 2020.
- CDFA PD/GWSS Board Website PD/GWSS Interactive Forum
- "Oleander leaf scorch". 10 July 2006. Archived from the original on 18 September 2006. Retrieved 15 February 2020.
- Wells, J. M.; Raju, B. C.; Hung, H.-Y.; Weisburg, W. G.; Mandelco-Paul, L.; Brenner, D. J. (1 April 1987). "Xylella fastidiosa gen. nov., sp. nov: Gram-Negative, Xylem-Limited, Fastidious Plant Bacteria Related to Xanthomonas spp". International Journal of Systematic Bacteriology. 37 (2): 136–143. ISSN 0020-7713.
- Catalano, Luigi (2015). "Xylella fastidiosa la più grave minaccia dell'olivicoltura italiana" (PDF). L'Informatore Agrario (in Italian) (16): 36–42. Archived from the original (PDF) on 18 June 2018. Retrieved 15 February 2020.
External links
- Type strain of Xylella fastidiosa at BacDive - the Bacterial Diversity Metadatabase
- "XF-ACTORS". XF-ACTORS(Xylella Fastidiosa Active Containment Through a multidisciplinary-Oriented Research Strategy). 2 February 2021. Retrieved 30 March 2021.
- "XF-ACTORS "Xylella Fastidiosa Active Containment Through a multidisciplinary-Oriented Research"". EIP-AGRI - European Commission. 30 August 2017. Retrieved 30 March 2021.