Rice hoja blanca virus
Encyclopedia
Rice hoja blanca virus (RHBV) is the agent of the most important viral disease of rice
in Latin America
. The disease is found in Mexico
, throughout Central America
and the Caribbean
region. In South America
the disease is endemic to Colombia
, Venezuela
, Ecuador
, Peru
, Suriname
, French Guiana
and Guyana
.
can reduce seed set and quality. RHBV epidemics are cyclic. During the peak of RHBV epidemics, yield losses at the country level have been estimated to be between 25% and 50%.
. The RHBV genome
consists of four single stranded linear RNA
species, and the total genome is estimated to be 17.6 kb The RNA 1 is 9.8 kb and encodes for an RNA dependent RNA polymerase on the negative strand. The RNA 2 is 3,620 nucleotide
s and encodes two proteins using the ambisense coding strategy. The RNA 3 consists of 2,299 nucleotides and encodes for two proteins using an ambisense coding strategy. The nucleoprotein gene (N) is encoded by the virus complementary strand of RNA 3. The RNA 4 consists of 1,991 nucleotides and encodes for two proteins using an ambisense coding strategy.
Rice
Rice is the seed of the monocot plants Oryza sativa or Oryza glaberrima . As a cereal grain, it is the most important staple food for a large part of the world's human population, especially in East Asia, Southeast Asia, South Asia, the Middle East, and the West Indies...
in Latin America
Latin America
Latin America is a region of the Americas where Romance languages – particularly Spanish and Portuguese, and variably French – are primarily spoken. Latin America has an area of approximately 21,069,500 km² , almost 3.9% of the Earth's surface or 14.1% of its land surface area...
. The disease is found in Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
, throughout Central America
Central America
Central America is the central geographic region of the Americas. It is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. When considered part of the unified continental model, it is considered a subcontinent...
and the Caribbean
Caribbean
The Caribbean is a crescent-shaped group of islands more than 2,000 miles long separating the Gulf of Mexico and the Caribbean Sea, to the west and south, from the Atlantic Ocean, to the east and north...
region. In South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
the disease is endemic to Colombia
Colombia
Colombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...
, Venezuela
Venezuela
Venezuela , officially called the Bolivarian Republic of Venezuela , is a tropical country on the northern coast of South America. It borders Colombia to the west, Guyana to the east, and Brazil to the south...
, Ecuador
Ecuador
Ecuador , officially the Republic of Ecuador is a representative democratic republic in South America, bordered by Colombia on the north, Peru on the east and south, and by the Pacific Ocean to the west. It is one of only two countries in South America, along with Chile, that do not have a border...
, Peru
Peru
Peru , officially the Republic of Peru , is a country in western South America. It is bordered on the north by Ecuador and Colombia, on the east by Brazil, on the southeast by Bolivia, on the south by Chile, and on the west by the Pacific Ocean....
, Suriname
Suriname
Suriname , officially the Republic of Suriname , is a country in northern South America. It borders French Guiana to the east, Guyana to the west, Brazil to the south, and on the north by the Atlantic Ocean. Suriname was a former colony of the British and of the Dutch, and was previously known as...
, French Guiana
French Guiana
French Guiana is an overseas region of France, consisting of a single overseas department located on the northern Atlantic coast of South America. It has borders with two nations, Brazil to the east and south, and Suriname to the west...
and Guyana
Guyana
Guyana , officially the Co-operative Republic of Guyana, previously the colony of British Guiana, is a sovereign state on the northern coast of South America that is culturally part of the Anglophone Caribbean. Guyana was a former colony of the Dutch and of the British...
.
Symptoms
The symptoms in rice are chlorotic streaks that can coalesce and cause the leaves to turn white. When young plants become infected, they are stunted and in severe cases the leaves turn necrotic and the plants die. Infections that occur before the emergence of the paniclePanicle
A panicle is a compound raceme, a loose, much-branched indeterminate inflorescence with pedicellate flowers attached along the secondary branches; in other words, a branched cluster of flowers in which the branches are racemes....
can reduce seed set and quality. RHBV epidemics are cyclic. During the peak of RHBV epidemics, yield losses at the country level have been estimated to be between 25% and 50%.
Biology
Rice hoja blanca virus is a member of the genus TenuivirusTenuivirus
Tenuivirus ls a name of genera of plant viruses. The type member is "Rice Stripe Virus." Other members of this genera include "Maize Stripe Virus," "Rice Hoja Blanca Virus'," and "Iranian Wheat Strip Virus." These plant viruses cause diseases in their host plants...
. The RHBV genome
Genome
In modern molecular biology and genetics, the genome is the entirety of an organism's hereditary information. It is encoded either in DNA or, for many types of virus, in RNA. The genome includes both the genes and the non-coding sequences of the DNA/RNA....
consists of four single stranded linear RNA
RNA
Ribonucleic acid , or RNA, is one of the three major macromolecules that are essential for all known forms of life....
species, and the total genome is estimated to be 17.6 kb The RNA 1 is 9.8 kb and encodes for an RNA dependent RNA polymerase on the negative strand. The RNA 2 is 3,620 nucleotide
Nucleotide
Nucleotides are molecules that, when joined together, make up the structural units of RNA and DNA. In addition, nucleotides participate in cellular signaling , and are incorporated into important cofactors of enzymatic reactions...
s and encodes two proteins using the ambisense coding strategy. The RNA 3 consists of 2,299 nucleotides and encodes for two proteins using an ambisense coding strategy. The nucleoprotein gene (N) is encoded by the virus complementary strand of RNA 3. The RNA 4 consists of 1,991 nucleotides and encodes for two proteins using an ambisense coding strategy.