View source for Banana bunchy top virus

{{Short description|Species of virus}}
{{virusbox
| parent  = Babuvirus
| species = Banana bunchy top virus
}}
[[File:Banana Bunch Top Virus.jpg|thumb|Banana bunchy top virus causes new leaves to be stunted and "bunchy", while leaf edges are deformed and yellow]]
'''''Banana bunchy top virus''''' (BBTV) is a [[crop virus|plant pathogenic virus]] of the family [[Nanoviridae]] known for infecting [[banana]] plants and other crops. It is [[aphid transmitted]].
==Definition==
Banana bunchy top is a viral disease caused by a single-stranded [[DNA virus]] called the banana bunchy top virus (BBTV). It was first identified in [[Fiji]] in 1879, and has spread around the world since then.<ref name= "NBII"/> Like many viruses, BBTV was named after the symptoms seen, where the infected plants are stunted and have "bunchy" leaves at the top.<ref name = "CTAHR">{{cite report | first1=Stephen A. | last1=Ferreira | first2=Eduardo E. | last2=Trujillo | first3=Desmond Y. | last3=Ogata | title=Banana Bunchy Top Virus | date=December 1997 | publisher=Cooperative Extension Service, College of Tropical Agriculture and Human Resources, [[University of Hawaii at Manoa]] | pages=1–4 | number=PD-12 | url=http://scholarspace.manoa.hawaii.edu/bitstream/10125/12378/PD-12.pdf}}</ref> The disease is transmitted from plant-to-plant in tropical regions of the world by [[aphid]]s,<ref name="Wang-Blanc-2021">{{cite journal | last1=Wang | first1=Xiao-Wei | last2=Blanc | first2=Stéphane | title=Insect Transmission of Plant Single-Stranded DNA Viruses | journal=[[Annual Review of Entomology]] | publisher=[[Annual Reviews (publisher)|Annual Reviews]] | volume=66 | issue=1 | date=2021-01-07 | issn=0066-4170 | doi=10.1146/annurev-ento-060920-094531 | pages=389–405| pmid=32931313 | doi-access=free }}</ref> [[banana aphid]]s which can also feed on ''[[Heliconia]]'' and flowering ginger (from the family [[Zingiberaceae]]), which is an important factor in control of the disease. There are no resistant varieties, so controlling the spread by vectors and plant materials are the only management methods.<ref name = "NBII"/> Symptoms include spotting any deformed plant appearance.{{cn|date=November 2022}}
==Transmission==
All [[babuvirus]]es are [[aphid transmitted]] including BBTV. Information is lacking regarding [[vector (epidemiology)|vector]]-virus interactions.<ref name="Wang-Blanc-2021"/>
==Host and symptoms==
Banana bunchy top disease affects the banana fruit and foliage, and is caused by a single-strand DNA virus, the banana bunchy top virus.<ref name="Herrera-Valencia, Virginia A. 2006">{{cite journal | last1=Herrera-Valencia | first1=Virginia A. | last2=Dugdale | first2=Benjamin | last3=Harding | first3=Robert M. | last4=Dale | first4=James L. | title=An iterated sequence in the genome of Banana bunchy top virus is essential for efficient replication | journal=[[Journal of General Virology]] | publisher=[[Microbiology Society]] | volume=87 | issue=11 | date=2006-11-01 | issn=0022-1317 | doi=10.1099/vir.0.82166-0 | pages=3409–3412| doi-access=free | pmid=17030877 }}</ref>  BBTV can infect species of the family Musaceae, which includes bananas, plantains, abaca, and more.<ref name = "NBII">{{GISD|141|Banana bunchy top virus (BBTV)}}</ref> The aphids also feed on ''Heliconia'' and flowering ginger, which are grown in the same regions as bananas and must be considered in management of the disease. It is best to establish a banana production area where these alternate hosts are not present.  Any age plants can be infected by this virus, but some varieties of banana, including the [[Cavendish banana|Cavendish]], are more susceptible to the virus.<ref name = "CTAHR"/>  In areas where the virus is less common, the disease is usually spread by planting diseased [[Suckers (botany)|suckers]] at the beginning of the season, which means the season is started with a diseased crop.<ref name="NBII"/>
The pathogen causes cytopathological effects in the [[phloem]] tissue, which is the damaging of the host cells caused by the virus.<ref name = "NBII"/> The damage causes many effects that help to diagnose and characterize the disease. The name of the disease comes from the symptom which occurs in older plants, in which the new leaves that are produced are narrower than normal, yellow, and flat, which causes a "bunchy" appearance at the top of the tree.<ref name = "CTAHR"/> If any fruit is produced, which is unusual, it will be deformed.<ref name = "CTAHR"/>  In addition, one of the most distinctive symptoms is "Morse code streaking"<ref name = "CTAHR"/> where the infected cells die and are lighter in color, causing irregular spots and dashes on the leaves that are easier to see when the waxy coating over the [[Petiole (botany)|petiole]] is rubbed away.{{cn|date=November 2022}}
==Distribution==
BBTV is a widespread disease in the tropics, and is present in Southeast Asia, the Philippines, Taiwan, [[Oceania]]<ref name="Wang-Blanc-2021" /> including most of the [[South Pacific islands]] and [[Hawaii]],<ref name="Wang-Blanc-2021" /> Pakistan (first found 1988, first identified 1991 or 1992),<ref name="Khalid-Stover-1993">
{{cite journal
|last1=Khalid
|first1=S.
|last2=Stover
|first2=R. H.
|journal=[[Plant Disease (journal)|Plant Disease]]
|year=1993
|volume=77
|page=101A
|publisher=[[American Phytopathological Society]]
|doi=10.1094/pd-77-0101a
|issn=0191-2917
|issue=1
|title=Disease Notes - First Report of Banana Bunchy Top Virus in Pakistan
}}
</ref> [[East Asia]],<ref name="Wang-Blanc-2021" /> parts of India,<ref name = "CTAHR" /> and is invading Africa {{as of|2021|lc=yes}}.<ref name="Wang-Blanc-2021" /><ref name = "CTAHR" /> It is especially problematic in East Asia, Oceania, and Hawaii.<ref name="Wang-Blanc-2021" /> It was first observed in Hawaii in 1989, and is now widespread on [[Oahu]], in the [[Kona District, Hawaii|Kona]] area, and on [[Kauai]].<ref name = "CTAHR"/> The disease is currently not present in Central or South America.<ref name = "CTAHR"/> The pathogen is not present everywhere bananas are grown, but is present in most areas where the vector is also present.<ref name="Dale-1987">{{cite book | last=Dale | first=James L. | title=Advances in Virus Research | chapter=Banana Bunchy Top: An Economically Important Tropical Plant Virus Disease | publisher=[[Elsevier]] | year=1987 | volume=33 | issn=0065-3527 | doi=10.1016/s0065-3527(08)60321-8 | pages=301–325 | pmid=3296696 | isbn=9780120398331 | chapter-url=https://books.google.com/books?id=-RY6PB_3iSUC&dq=banana+bunchy+top+resistance&pg=PA301}}</ref>{{rp|301-03}} These aphids are most likely native to Southeast Asia, but they are present in most areas in the tropics, and almost everywhere bananas are grown.<ref name = "Mau et al">{{cite web | title=''Pentalonia nigronervosa'' | website=Crop Knowledge Master | url=http://www.extento.hawaii.edu/kbase/crop/Type/pentalon.htm | access-date=2022-01-28 | last1=Mau | first1=Ronald F. L. | first2=Jayma L. Martin | last2=Kessing | first3=Victoria L. | last3=Tenbrink | first4=Arnold H. | last4=Hara | publisher=[[University of Hawaii]] Department of Entomology | date=December 1994}}</ref> BBTV is spread to new areas by poor agricultural practices, and can be transmitted on plant material from the family [[Musaceae]], the virus' host.<ref name = "CTAHR"/>
==Disease cycle==
[[File:Banana bunchy top virus symptoms.jpg|thumb|left|A banana plant affected by bunchy top virus]]
BBTV is the sole member of the genus ''Babuvirus'' in the family Nanoviridae.<ref name="Herrera-Valencia, Virginia A. 2006"/>  The genome of BBTV is made up of at least six circular, single-stranded DNA components, each about 1 kilo-base pair in length.<ref name="Herrera-Valencia, Virginia A. 2006"/> Replication takes place by rolling circle replication, a unidirectional nucleic acid replication that can result in rapid synthesis of single-strands of DNA.<ref name="Herrera-Valencia, Virginia A. 2006"/>  There are specific virus-like particles that have been proposed as the virions of BBTV but there are still discrepancies in the scientific world about the exact relationship between these virions and the single-stranded DNA virus.<ref name = "Harding et al">{{cite journal | last1=Harding | first1=Robert M. | last2=Burns | first2=Thomas M. | last3=Dale | first3=James L. | title=Virus-like particles associated with banana bunchy top disease contain small single-stranded DNA | journal=[[Journal of General Virology]] | publisher=[[Microbiology Society]] | volume=72 | issue=2 | date=1991-02-01 | issn=0022-1317 | doi=10.1099/0022-1317-72-2-225 | pages=225–230| pmid=1993864 | doi-access=free }}</ref> Nevertheless, it was demonstrated that the associated ssDNA molecules are transmitted with the disease and therefore are designated as the pathogen.<ref name = "Harding et al"/>
It is known that Banana aphid (''[[Pentalonia nigronervosa]]'') transmits the virus from infected to healthy plants by feeding.  Aphids feed on the plant phloem tissues by injecting their thin, flexible stylet into the epidermis of the plant tissue until it reaches the phloem of the leaves.  Then the aphid injects saliva and sucks the cell contents. This ingestion of viral components is done inadvertently by the aphid. Vector transmission of the BBTV is circulative and non-propagative, meaning that transmission of the virus occurs from and to the phloem tissues and the virus does not replicate within the aphid’s midgut. Acquisition of the virus by the banana aphid requires about 18 hours of feeding and then the aphid can retain the virus for approximately two weeks.<ref name = "CTAHR" />  The retransmission of this virus can happen after as little as two hours of feeding on a healthy plant however it takes about a month for the BBTV symptoms to appear after infection.<ref name = "CTAHR" /> To infect, the carrier aphid can feed on the banana plant for as few as 15 minutes, but more often a couple hours, as the longer feeding time will increase the odds of transmission.<ref name = "NBII"/> The suckers produced on infected plants that would usually be used for planting the next season will also be diseased, which is one way the disease can spread from year to year.<ref name = "NBII"/> Banana aphids also have the capability to feed on ''Heliconia'' and flowering ginger; however, these alternate hosts of the aphid vector are not hosts of the virus.<ref name = "CTAHR" /> The ability of banana aphids to feed on alternate hosts is important to keep in mind when attempting to control the virus.{{cn|date=November 2022}}
==Management==
There are no resistant varieties of banana against BBTV, so the most common method of control is chemical control of the aphid vectors.<ref name = "CTAHR"/><ref name = "Harish et al">{{cite journal | last1=Harish | first1=S. | last2=Kavino | first2=M. | last3=Kumar | first3=N. | last4=Saravanakumar | first4=D. | last5=Soorianathasundaram | first5=K. | last6=Samiyappan | first6=R. | title=Biohardening with Plant Growth Promoting Rhizosphere and Endophytic bacteria induces systemic resistance against ''Banana bunchy top virus'' | journal=[[Applied Soil Ecology]] | publisher=[[Elsevier]] | volume=39 | issue=2 | year=2008 | issn=0929-1393 | doi=10.1016/j.apsoil.2007.12.006 | pages=187–200| bibcode=2008AppSE..39..187H }}</ref> Another way to help control the virus is to remove and destroy any infected plants before the virus can spread, which is a practice known as roguing.<ref name = "CTAHR"/> Quarantines are also implemented to prevent the import of any potentially infected plant materials, including one in Hawaii that prevents the movement of anything except fruits from the island of Oahu to any other island, since BBTV is widespread in Oahu.<ref name = "CTAHR" /> Fruit is not often produced on infected plants, but if it is, the fruit will be deformed, which easily identifies if there is any virus present in the fruits to comply with quarantine regulations.<ref name = "CTAHR"/> Since bananas are not the only host, the alternate hosts for both the virus and the aphid must also be monitored for disease, and sprayed with pesticides to control the aphids more.<ref name = "NBII"/><ref name = "CTAHR"/> When planting at the beginning of the season, the seed material or suckers should be obtained from BBTV free areas of the world or from cultures that are grown and developed to be free of the virus.<ref name = "CTAHR"/> Currently, there is ongoing research into biopriming, or inducing systemic resistance by using bacteria that live inside the host but do not infect.<ref name = "Harish et al"/>
Control of banana bunchy top is achieved by killing the banana aphids then destroying all infected material. First, the aphids should be killed on the infected banana material, and then all the plant material should be destroyed to prevent the spread of the virus.<ref name = "CTAHR" /> Infected banana plants can be sprayed with an insecticide like [[Carbaryl|Sevin]] to reduce or get rid of the aphid population, since control of viruses starts with control of the vectors.<ref name = "CTAHR" /> The agriculture department, however, recently obtained an [[United States Environmental Protection Agency|EPA]] waiver for the pesticide [[Provado]] is a means of controlling the [[aphid]]s that spread the disease.{{cn|date=November 2022}}
==Importance==
Banana bunchy top disease is the most serious virus disease of banana worldwide.<ref name = "CTAHR" /> Diseased plants rarely produce fruit and when they do, the fruit is stunted and twisted. However, in the rare scenario that a diseased plant does produce fruit that reaches maturity, it is edible. The banana bunchy top disease has had a huge impact on the banana industry in Hawaii and Australia and among other areas of the world. The disease was first seen on the Hawaiian island of Oahu in 1989 and by 2002, only 13 years later, it was a major disease on four of the Hawaiian islands (Hawaii, Oahu, Kauai and Maui).<ref name = "Banana Bunchy Top">{{cite web | title=Banana Bunchy Top Disease | website=[[University of Hawaii at Manoa]] | url=http://www.ctahr.hawaii.edu/bbtd/b2_files/frame.htm}}</ref>  The movement of BBTD was mostly facilitated by human movement of diseased plant material and banana aphids from island to island.  In the 1920s it almost completely destroyed the banana growing industry in Australia.<ref name = "Thomas, John E. 1991">{{Cite journal|author1=Thomas, John E.|author2=Ralf G. Dietzgen|name-list-style=amp|title=Purification, characterization and serological detection of virus-like particles associated with banana bunchy top disease in Australia.|journal=Journal of General Virology|volume=72|issue=2|date=1991|pages=217–24|others=University of Hawaii at Manoa|doi=10.1099/0022-1317-72-2-217|pmid=1993863|url=https://www.microbiologyresearch.org/docserver/fulltext/jgv/72/2/JV0720020217.pdf?expires=1594265571&id=id&accname=guest&checksum=A19F7D5143420804EAE2FD2B361AD90D|doi-access=free}}</ref>
{| class="wikitable"
|-
! Island !! Year !! Month !! City
|-
| Oahu || 1989 || July || Punaluu
|-
| Hawaii || 1995 || October || North Kona
|-
| Kauai || 1997 || September || Kilauea Town
|-
| Maui || 2002 || December || Pukalani
|}
While BBTV certainly has a huge impact on the industrial scale of banana production, it can also be devastating to subsistence farmers who depend on their crop to feed their families and provide income. Small farmers will often lose the uphill battle of fighting against BBTV in their crop.  Once established, it is very difficult to eradicate and manage the disease.<ref name = "Harish et al"/> The difficulty of eradication is perpetuated by a number of reasons.  First of all, the disease is caused by a vector-transmitted virus and this virus is not completely understood yet.<ref name = "Harding et al"/> Secondly, all bananas are susceptible to the disease and no resistant varieties have been discovered or made commercially available. Lastly, the control methods are quite demanding,  including chemical treatment for the aphid vectors, removal of all infected tissue (aka [[roguing]]), quarantining plants and monitoring alternate vector feeding sites.<ref name = "CTAHR"/>
==References==
* http://www.galegroup.com
* http://www.ebi.ac.uk
* http://archives.starbulletin.com/2004/04/24/news/story7.html
* http://archives.starbulletin.com/2004/05/01/news/story5.html
{{Reflist}}
==External links==
{{Commons category}}
{{Wikispecies}}
* [https://web.archive.org/web/20070612150431/http://phene.cpmc.columbia.edu/ICTVdB/00.093.0.02.001.htm ICTVdB - The Universal Virus Database: Banana bunchy top virus]
* [http://www.virology.net/Big_Virology/BVFamilyGroup.html Family Groups - The Baltimore Method] {{Webarchive|url=https://web.archive.org/web/20130330144456/http://www.virology.net/Big_Virology/BVFamilyGroup.html |date=2013-03-30 }}
* [http://www.ctahr.hawaii.edu/bbtd/ University of Hawaii at Manoa, College of Tropical Agriculture and Human Resources - Banana Bunchy Top page including pictures and video link]
* [http://www.promusa.org/tiki-index.php?page=Bunchy+top Bunchy top], a description of banana bunchy top disease on Musapedia
* {{cite web | title=Banana bunchy top | website=[[Business Queensland]] | date=2019-07-31 | url=http://www.business.qld.gov.au/industries/farms-fishing-forestry/agriculture/crop-growing/priority-pest-disease/banana-bunchy-top | access-date=2021-08-09}}
* {{cite web | title=Banana Bunchy Top | website=Australian Banana Growers | date=2018-12-17 | url=http://abgc.org.au/banana-bunchy-top/ | access-date=2021-08-09}}
{{Taxonbar|from=Q4853861}}
[[Category:Banana diseases]]
[[Category:Viral plant pathogens and diseases]]
[[Category:Nanoviridae]]