Pepper mild mottle virus (PMMoV) is a plant pathogenic virus that occurs worldwide on species of field grown bell, hot and ornamental pepper species. It is caused by members of the plant virus genus Tobamovirus—otherwise known as the tobacco mosaic virus family. Tobamovirus are viruses that contain positive sense RNA genomes that infect plants.[1] Symptoms of the disease vary depending on the cultivar. Typical symptoms include the chlorosis of leaves, stunting, and distorted and lumpy fruiting structures. The virus is spread by mechanical transmission and infected seeds. Avoidance is the best means of controlling the disease because once a plant is infected it cannot be treated. Only seeds that have been tested and treated for the pathogen should be planted.[2]
| Pepper mild mottle virus | |
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| Pepper infected with PMMoV | |
Virus classification 
| |
| (unranked): | Virus |
| Realm: | Riboviria |
| Kingdom: | Orthornavirae |
| Phylum: | Kitrinoviricota |
| Class: | Alsuviricetes |
| Order: | Martellivirales |
| Family: | Virgaviridae |
| Genus: | Tobamovirus |
| Species: | Pepper mild mottle virus
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History
editThe origin of PMMoV has been linked to Tomato mosaic virus, as they both reside in the Tobacco mosaic virus family. The Tunisian Journal of Plant Protection brought about the link between PMMoV to ToMV from a French study dating back to 1964. ToMV affects a wide range of Solanaceous crops and a strain of this virus likely mutated into PMMoV.[3]
Host and symptoms
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Pepper mild mottle virus is the major viral pathogen of peppers (Capsicum spp.).[4] The host range of PMMoV include most cultivars and species of pepper (Capsicum spp.). This virus strain does not infect tomato, eggplant, or tobacco; however, other members of the genus Tobamovirus can infect these other hosts.[5] PMMoV is one of at least 4 different species of Tobamovirus that infect peppers.[6] The others include Tobacco mosaic virus (TMV), Tomato mosaic virus (ToMV) and Tobacco mild green mosaic virus (TMGMV).
The pathogen is known to occur throughout the world and it frequently results in significant crop losses or reductions in both field and greenhouse plantings. The virus has been identified in places like Australia, Japan, China, Taiwan, Europe, and North Africa. Since 1997, PMMoV has been the cause of many major outbreaks in the southeastern states namely Georgia and Florida.[4]
Symptoms caused by this pathogen vary based on the specific host cultivar; however, a majority of the symptoms are very similar between the different hosts. Symptoms usually include various degrees of mottling, chlorosis, curling, dwarfing, and distortion of the fruit, leaves, and even whole plants. The symptoms on fruit include: a reduction in size, mottling and color changes, and an obvious distorted and lumpy appearance. Also, many times brown necrotic streaks or splotches can be seen on the leaves and fruit. The symptoms can easily be seen on new growth, and they are far more pronounced if the plant was infected when it was young rather than when it was older.[7]
The disease is harmful because of the mild foliar symptoms (chlorosis, necrosis, etc.) and due to this many times the pathogen goes unnoticed until the more evident symptoms on the fruit appear. This is why there are higher yield losses because symptoms only become evident during the fruiting stage right before the crops are supposed to harvested.[citation needed]
Disease transmission
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PMMoV is a rigid rod shaped virus pathogen that can be easily transmitted to healthy plants via mechanical inoculation or contact between plants or another medium that can carry the pathogen such as hands, gloves, and clothing. The virus is commonly found on the outer seed coat and very rarely in the endosperm of seeds of the infected plants. Being seedborne, the virus primarily infects through mechanical contamination during seed transplanting and other agricultural procedures. It enters the plant/seed through microscopic abrasions or wounds. The virus is in vitro, which in this case means it can survive in an isolated environment, and being highly infectious it can easily be transmitted during normal crop maintenance. PMMoV is exceptionally stable and it is known to survive for extended periods of time in plant debris and on greenhouse structures, pots, and horticultural tools. There are no known insect vectors; however, humans can be considered the main vector for this pathogen.[8]
Environment
editThe virus is widespread and is found almost anywhere peppers are grown, this is because the virus is most often introduced with the pepper seed. The virus moves long distances on the seed and moves short distances via plant-to-plant contact, handling of plants by contaminated implements and workers aids in the spread of the virus.[9] Soils with low organic matter content, specifically humus will much more readily promote the adsorption of PMMoV. Specifically, the allophanic clays and iron minerals in these soils will promote the adsorption of PMMoV.[10]
Disease incidence has occurred mainly in greenhouse environments and hot, humid environments like southwest and southeast Florida and in regions like North Africa, and Japan. This is an indication of the type of soil that is optimal for the virus; warm or hot and humid. Greenhouses, specifically, are an ideal production environment for rapid spread of the disease.[11]
Prevention, control and management
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Up until 2005, the primary means of prevention was a pre-plant treatment of bromomethane or methyl bromide. The import and production of this fumigation chemical was banned under the Montreal Protocol. A modern organic method of prevention was found by a Japanese study on soil adsorptions role in the adsorption of PMMoV. The study found that increased humus content in a soil will have an inhibitory effect on PMMoV adsorption.[10]
As with all plant viruses, but especially with those in the genus Tobamovirus, avoidance is the best means of control. Growers must practice good sanitation procedures and only plant clean seeds. Growers must also use caution when handling plants, plants with abrasions or wounds give the virus an opportunity to enter the tissue of the plant. There are no chemical or biological control methods that can be used to control the disease once the plant is infected. Though often a challenge, accurate identification of PMMoV is key to successful control of the disease.
Diseased plant material will remain infectious until completely broken down. Tillage, increased irrigation, and high temperatures encourage the breakdown of plant material in the soil. Any infected plant material in the soil can serve as a source of inoculum for subsequent crops so crop rotation should be practiced, if possible. Volunteer peppers and weeds, particularly those in the family Solanaceae (such as nightshades), should be removed to reduce possible sources of infections. Due to the fact that smoke can spread the disease, burial or composting of the diseased plants should be implemented rather than burning. The composted diseased plant remains should not be used on a pepper crop or other Solanaceous crops.[5]
Importance
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Controlling the virus is important for pepper production worldwide, but recent research shows that this plant disease may be transmitted to humans.[14][15]
PMMoV is an indicator of fecal pollution in the environment. An early study set in the United States and Singapore detected PMMoV in fecal samples from most participants, at concentrations up to 109 copies per gram of dry feces[16] and is consistently found in wastewater from around the world at concentrations greater than 1 million copies per milliliter of raw sewage.[17] Quantitative PCR is used to determine the abundance of PMMoV in raw sewage, treated wastewater, seawater exposed to wastewater, and fecal samples and/or intestinal homogenates from a wide variety of animals.
PMMoV is commonly found in surface waters impacted by anthropogenic activity (namely wastewater), such as in groundwater, streams, lakes, rivers, esturaries and some oceans. PMMoV is found in drinking water, including at trace levels in countries such as the USA,[18] Japan[19] and Sweden.[20] Compared to other indicator viruses and bacteria associated with wastewater such as Escherichia coli or adenovirus, PMMoV is more resistant to established water and wastewater treatment processes, making it ideal for tracking anthropogenic pollution in the environment.[21]
References
edit- ^ Hu Q, Hollunder J, Niehl A, Kørner CJ, Gereige D, Windels D, et al. (May 2011). "Specific impact of tobamovirus infection on the Arabidopsis small RNA profile". PLOS ONE. 6 (5): e19549. Bibcode:2011PLoSO...619549H. doi:10.1371/journal.pone.0019549. PMC 3091872. PMID 21572953.
- ^ Plant Pathology Fact Sheet: Pepper mild mottle virus http://ufdc.ufl.edu/IR00001690/00001
- ^ Mnari-Hattab M, Ezzaier K (2006). "Biological, Serological, and Molecular Characterization of Pepper mild mottle virus (PMMoV) in Tunisia" (PDF). Tunisian Journal of Plant Protection. 1 (1): 1–12. Archived from the original (PDF) on 2016-03-03. Retrieved 2012-10-25.
- ^ a b Jarret RL, Gillaspie AG, Barkley NA, Pinnow DL (2008). "The Occurrence and Control of Pepper Mild Mottle Virus (PMMoV) in the USDA/ARS Capsicum Germplasm Collection". Seed Technology Journal. 30 (1): 26–36.
- ^ a b Roberts PD, Adkins S. "Pepper Mild Mottle Virus". University of Florida IFAS Extension. Archived from the original on 6 August 2010.
- ^ Wetter C (1984). "Serological Identification of Four Tobamoviruses Infected Pepper" (PDF). Plant Disease. 68 (7): 597–599. doi:10.1094/pd-69-597.
- ^ Baker C, Adkins S (2000). "Peppers, Tomatoes, and Tobamoviruses" (PDF). Plant Pathology Circular No. 400. Florida Department of Agriculture & Conservation Services, Division of Plant Industry.
- ^ Nagvi SA, ed. (2004). Diseases of Fruits and Vegetables: Diagnosis and Management. Springer. ISBN 9781402018268.
- ^ "Pepper Mild Mottle Virus". American Vegetable Grower. 59 (9): 30. 2011.
- ^ a b Yoshimoto R, Sasaki H, Takahashi T, Kanno H, Nanzyo M (2012). "Contribution of Soil Components to Adsorption of Pepper Mild Mottle Virus by Japanese Soils". Soil Biology & Biochemistry. 46: 96–102. Bibcode:2012SBiBi..46...96Y. doi:10.1016/j.soilbio.2011.12.006.
- ^ "UFDC". ufdc.ufl.edu.
- ^ Balique F, Lecoq H, Raoult D, Colson P (April 2015). "Can plant viruses cross the kingdom border and be pathogenic to humans?". Viruses. 7 (4): 2074–98. doi:10.3390/v7042074. PMC 4411691. PMID 25903834.
- ^ Jiwaji M, Matcher GF, de Bruyn MM, Awando JA, Moodley H, Waterworth D, et al. (2019-06-04). "Providence virus: An animal virus that replicates in plants or a plant virus that infects and replicates in animal cells?". PLOS ONE. 14 (6): e0217494. Bibcode:2019PLoSO..1417494J. doi:10.1371/journal.pone.0217494. PMC 6548363. PMID 31163039.
- ^ Aguado-García Y, Taboada B, Morán P, Rivera-Gutiérrez X, Serrano-Vázquez A, Iša P, et al. (August 2020). "Tobamoviruses can be frequently present in the oropharynx and gut of infants during their first year of life". Scientific Reports. 10 (1): 13595. Bibcode:2020NatSR..1013595A. doi:10.1038/s41598-020-70684-w. PMC 7423923. PMID 32788688.
- ^ Liu R, Vaishnav RA, Roberts AM, Friedland RP (2013-04-03). "Humans have antibodies against a plant virus: evidence from tobacco mosaic virus". PLOS ONE. 8 (4): e60621. Bibcode:2013PLoSO...860621L. doi:10.1371/journal.pone.0060621. PMC 3615994. PMID 23573274.
- ^ Zhang, Tao; Breitbart, Mya; Lee, Wah Heng; Run, Jin-Quan; Wei, Chia Lin; Soh, Shirlena Wee Ling; Hibberd, Martin L; Liu, Edison T; Rohwer, Forest; Ruan, Yijun (20 December 2005). Dangl, Jeffrey (ed.). "RNA Viral Community in Human Feces: Prevalence of Plant Pathogenic Viruses". PLOS Biology. 4 (1). Public Library of Science (PLoS): e3. doi:10.1371/journal.pbio.0040003. ISSN 1545-7885. PMC 1310650. PMID 16336043.
- ^ Rosario K, Symonds EM, Sinigalliano C, Stewart J, Breitbart M (November 2009). "Pepper mild mottle virus as an indicator of fecal pollution". Applied and Environmental Microbiology. 75 (22): 7261–7. Bibcode:2009ApEnM..75.7261R. doi:10.1128/AEM.00410-09. PMC 2786529. PMID 19767474.
- ^ Stokdyk, Joel P.; Firnstahl, Aaron D.; Walsh, James F.; Spencer, Susan K.; de Lambert, Jane R.; Anderson, Anita C.; Rezania, Lih-In W.; Kieke, Burney A.; Borchardt, Mark A. (2020). "Viral, bacterial, and protozoan pathogens and fecal markers in wells supplying groundwater to public water systems in Minnesota, USA". Water Research. 178. Elsevier BV: 115814. Bibcode:2020WatRe.17815814S. doi:10.1016/j.watres.2020.115814. ISSN 0043-1354. PMID 32325219. S2CID 216109967.
- ^ Canh, Vu Duc; Torii, Shotaro; Furumai, Hiroaki; Katayama, Hiroyuki (2021). "Application of Capsid Integrity (RT-)qPCR to Assessing Occurrence of Intact Viruses in Surface Water and Tap Water in Japan". Water Research. 189. Elsevier BV: 116674. Bibcode:2021WatRe.18916674C. doi:10.1016/j.watres.2020.116674. ISSN 0043-1354. PMID 33279831. S2CID 227526393.
- ^ Wang, Hao; Kjellberg, Inger; Sikora, Per; Rydberg, Henrik; Lindh, Magnus; Bergstedt, Olof; Norder, Heléne (2020). "Hepatitis E virus genotype 3 strains and a plethora of other viruses detected in raw and still in tap water". Water Research. 168. Elsevier BV: 115141. Bibcode:2020WatRe.16815141W. doi:10.1016/j.watres.2019.115141. hdl:2077/61688. ISSN 0043-1354. PMID 31590036. S2CID 203925772.
- ^ Kitajima, Masaaki; Iker, Brandon C.; Pepper, Ian L.; Gerba, Charles P. (2014). "Relative abundance and treatment reduction of viruses during wastewater treatment processes — Identification of potential viral indicators". Science of the Total Environment. 488–489. Elsevier BV: 290–296. Bibcode:2014ScTEn.488..290K. doi:10.1016/j.scitotenv.2014.04.087. ISSN 0048-9697. PMID 24836386.