Maize streak virus (MSV) is a virus primarily known for causing maize streak disease (MSD) in its major host, and which also infects over 80 wild and domesticated grasses. It is an insect-transmitted

pathogen In biology, a pathogen (, "suffering", "passion" and , "producer of"), in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a Germ theory of d ...

maize Maize (; ''Zea mays''), also known as corn in North American English, is a tall stout grass that produces cereal grain. It was domesticated by indigenous peoples in southern Mexico about 9,000 years ago from wild teosinte. Native American ...

in the genus ''

Mastrevirus ''Mastrevirus'' is a genus of ssDNA viruses, in the family ''Geminiviridae''. Mostly monocotyledonous plants serve as natural hosts. They are vectored by planthoppers. There are 50 species in this genus. Diseases associated with this genus inclu ...

'' of the family ''

Geminiviridae ''Geminiviridae'' is a family of plant viruses that encode their genetic information on a circular genome of single-stranded (ss) DNA. The family contains 15 genera. Diseases associated with this family include: bright yellow mosaic, yellow mosa ...

'' that is

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

in sub-Saharan Africa and neighbouring Indian Ocean island territories such as

Madagascar Madagascar, officially the Republic of Madagascar, is an island country that includes the island of Madagascar and numerous smaller peripheral islands. Lying off the southeastern coast of Africa, it is the world's List of islands by area, f ...

Mauritius Mauritius, officially the Republic of Mauritius, is an island country in the Indian Ocean, about off the southeastern coast of East Africa, east of Madagascar. It includes the main island (also called Mauritius), as well as Rodrigues, Ag ...

and La Reunion. The A-strain of MSV ( MSV-A) causes sporadic maize streak disease

epidemics An epidemic (from Ancient Greek, Greek ἐπί ''epi'' "upon or above" and δῆμος ''demos'' "people") is the rapid spread of disease to a large number of Host (biology), hosts in a given population within a short period of time. For example ...

throughout the maize-growing regions of Africa. MSV was first described by the South African entomologist Claude Fuller who referred to it in a 1901 report as "mealie variegation". The development of conventionally resistant maize varieties has been a priority since the 1950s in Kenya, Nigeria, South Africa and elsewhere, with a good deal of success: however, there are several genes associated with resistance, and breeding is complex. Transgenically resistant or genetically modified maize varieties were under development in South Africa, but the project has terminated without field trials of the candidate maize lines that were developed. Maize streak resistance is an important trait to maize breeders.

Forward genetics Forward genetics is a molecular genetics approach of determining the genetic basis responsible for a phenotype. Forward genetics provides an unbiased approach because it relies heavily on identifying the genes or genetic factors that cause a partic ...

is increasingly being used. MSV is mainly

vector Vector most often refers to: * Euclidean vector, a quantity with a magnitude and a direction * Disease vector, an agent that carries and transmits an infectious pathogen into another living organism Vector may also refer to: Mathematics a ...

ed by '' Cicadulina mbila'', and other '' Cicadulina'' species, such as '' C. storeyi'', '' C. arachidis'' and '' C. dabrowski'', are also able to transmit the virus. Typical of all mastreviruses, MSV's circular, ~2.7-Kb monopartite single-stranded (ss) DNA genome encodes only four proteins. Bidirectional transcription from a long intergenic region (LIR) results in the virion-sense expression of a movement protein (MP) and a coat protein (CP), and the complementary-sense expression of the replication-associated proteins, Rep and RepA. Whereas the MP and CP are involved in virus movement and encapsidation, Rep is an essential initiator of virus replication, and RepA is a regulator of host and viral gene transcription. Due to genome size restrictions, MSV usurps host DNA replication and double-stranded DNA break repair proteins to replicate its genome via, respectively, rolling-circle and recombination-dependent mechanisms.

References

{{DEFAULTSORT:Maize Streak Virus Maize diseases Viral plant pathogens and diseases Geminiviridae