''Papaya leaf curl virus'' (PaLCuV) is a DNA virus from the genus ''

Begomovirus ''Begomovirus'' is a genus of viruses, in the family ''Geminiviridae''. They are plant viruses that as a group have a very wide host range, infecting dicotyledonous plants. Worldwide they are responsible for a considerable amount of economic dam ...

'' and the family ''

Geminiviridae ''Geminiviridae'' is a family of plant viruses that encode their genetic information on a circular genome of single-stranded (ss) DNA. There are 520 species in this family, assigned to 14 genera. Diseases associated with this family include: bri ...

''. PaLCuV causes severe disease in papaya (''

Carica papaya The papaya (, ), papaw, () or pawpaw () is the plant species ''Carica papaya'', one of the 21 accepted species in the genus ''Carica'' of the family Caricaceae. It was first domesticated in Mesoamerica, within modern-day southern Mexico and C ...

''), but can sometimes infect other crops such as

tobacco Tobacco is the common name of several plants in the genus '' Nicotiana'' of the family Solanaceae, and the general term for any product prepared from the cured leaves of these plants. More than 70 species of tobacco are known, but the ...

tomato The tomato is the edible berry of the plant ''Solanum lycopersicum'', commonly known as the tomato plant. The species originated in western South America, Mexico, and Central America. The Mexican Nahuatl word gave rise to the Spanish word ...

. It can be found in tropical and subtropical regions primarily in

India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...

, but closely related species have also been detected in countries such as

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

Malaysia Malaysia ( ; ) is a country in Southeast Asia. The federation, federal constitutional monarchy consists of States and federal territories of Malaysia, thirteen states and three federal territories, separated by the South China Sea into two r ...

Nigeria Nigeria ( ), , ig, Naìjíríyà, yo, Nàìjíríà, pcm, Naijá , ff, Naajeeriya, kcg, Naijeriya officially the Federal Republic of Nigeria, is a country in West Africa. It is situated between the Sahel to the north and the Gulf o ...

and

South Korea South Korea, officially the Republic of Korea (ROK), is a country in East Asia, constituting the southern part of the Korea, Korean Peninsula and sharing a Korean Demilitarized Zone, land border with North Korea. Its western border is formed ...

. This virus is transmitted by an insect vector from the family ''

Aleyrodidae Whiteflies are Hemipterans that typically feed on the undersides of plant leaves. They comprise the family Aleyrodidae, the only family in the superfamily Aleyrodoidea. More than 1550 species have been described. Description and taxonomy The A ...

'' and order ''

Hemiptera Hemiptera (; ) is an order (biology), order of insects, commonly called true bugs, comprising over 80,000 species within groups such as the cicadas, aphids, planthoppers, leafhoppers, Reduviidae, assassin bugs, Cimex, bed bugs, and shield bugs. ...

'', the whitefly '' Bemisia tabaci''. PaLCuV has been responsible for several epidemics and causes severe economic losses. Because of the broad diversity of these viruses, their characterization and control remains difficult.

Genome

This virus typically consists of a bipartite circular single-stranded (ss) DNA molecule (2400–2800 nt in size), and betasatellite (1350-1400 nt in size). Several beta satellites are associated with PaLCuV, and they likely play a role in symptom development. Some alpha satellites have also been associated with PaLCuV. This virus has similar coat protein structure and genome organization to that of other begomoviruses such as TYLCV.

Transmission

PaLCuV is transmitted by the insect vector '' Bemisia tabaci'' in a persistent-circulative nonpropagative manner. The wide range of host species, including several weeds plays a role in its broad transmission.

Agricultural importance

The main symptoms are severe curling and thickening of veins on leaves. The plants are also reduced in size. Severely affected plants produce fewer, smaller, and deformed fruits. This virus can cause significant yield losses in orchards. Losses may be as severe as 90–100%, especially when other virus species such as '' Papaya ringspot virus'' (PRSV) are present. Treatments that are commonly used for this disease include insecticides and removing infected plants. There are no known varieties with genetic resistance at this time, but there are on-going efforts to discover and breed papaya with natural resistance.

Epidemiology

PaLCuV is found in tropical and subtropical regions, and it significantly affects papaya production in India's major papaya growing regions. The disease was first described in 1939, while the causal virus was first detected in India in 1998. There are closely related virus species including: * ''Papaya leaf crumple virus'' * ''Papaya leaf curl China virus'' * ''Papaya leaf curl Guandong virus'' PaLCuV is related to '' Tomato leaf curl New Delhi virus'' (ToLCNDV), in some cases sharing 97% sequence identity.

Management

Currently, the most widespread treatments used to control the spread of PaLCuV are a wide range of insecticides as well as crop rotation. Rouging infected plants and destroying infected fields is also used when necessary. The usage of large quantities of insecticides to control vector populations is not ideal, and other cultural methods to control vector populations are of increasing importance to a complete integrated pest management strategy. Other strategies include trying to engineer resistance through RNAi much like with the 'Rainbow' cultivar of papaya and PRSV.

References

{{Taxonbar, from=Q18978756 Begomovirus Viral plant pathogens and diseases