''Maize dwarf mosaic virus'' (MDMV) is a pathogenic

plant virus Plant viruses are viruses that affect plants. Like all other viruses, plant viruses are obligate intracellular parasites that do not have the molecular machinery to replicate without a host. Plant viruses can be pathogenic to higher plants. M ...

of the family ''

Potyviridae ''Potyviridae'' is a family of positive-strand RNA viruses that encompasses more than 30% of known plant viruses, many of which are of great agricultural significance. The family has 12 genera and 235 species, three of which are unassigned to a ...

''. Depending on the corn plant’s growth stage, the virus can have severe implications to the corn plant’s development which can also result in economic consequences to the producer of the crop.

Importance

Maize (''

Zea mays Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. Th ...

'') is a major cereal crop; it is third behind rice and wheat in production. An average of 380 million tons are produced annually by 53 countries. Maize is the most widely grown crop ranging from tropical areas with altitudes over 3000 m to temperate areas extending as far north as the 65th latitude. MDMV is the most serious virus of

sweet corn Sweet corn (''Zea mays'' convar. ''saccharata'' var. ''rugosa''), also called sugar corn and pole corn, is a variety of maize grown for human consumption with a high sugar content. Sweet corn is the result of a naturally occurring recessive muta ...

. If corn plants are infected with MDMV, ear formation and development are slowed leading to grain yield loss. The damage from MDMV can cause the halting of ear formation and development, ultimately leading to the production of barren ears and direct yield loss. There can be losses of up to 42% on early planted field corn. If corn is planted late MDMV can cause 75% or more loss on

inbred Inbreeding is the production of offspring from the mating or breeding of individuals or organisms that are closely related genetically. By analogy, the term is used in human reproduction, but more commonly refers to the genetic disorders and o ...

and hybrid varieties. The number of ears per plant is reduced by MDMV infection and the fresh weight of these ears can be reduced by 30%.

Pathogenesis

MDMV is caused by various strains. There are five strains A, C, D, E, and F. They differ in biological, serological, and nucleotide sequences. The vector for MDMV transmission is

aphids Aphids are small sap-sucking insects and members of the superfamily Aphidoidea. Common names include greenfly and blackfly, although individuals within a species can vary widely in color. The group includes the fluffy white woolly aphids. A t ...

. There are 15 aphid species that can non-persistently transmit MDMV. The aphids mainly feed on the family

Poaceae Poaceae () or Gramineae () is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos and the grasses of natural grassland and species cultivated in lawns an ...

. MDMV overwinters in alternate hosts. These hosts range is

sorghum ''Sorghum'' () is a genus of about 25 species of flowering plants in the grass family (Poaceae). Some of these species are grown as cereals for human consumption and some in pastures for animals. One species is grown for grain, while many othe ...

, maize, and

Johnson grass Johnson grass or Johnsongrass, ''Sorghum halepense'', is a plant in the grass family, Poaceae, native to Asia and northern Africa. The plant has been introduced to all continents except Antarctica, and most larger islands and archipelagos. It re ...

. Symptoms appear six weeks after aphids feed and transmit the virus. The aphid acquires the virus within seconds of feeding on an infected plant, either maize, Johnson grass, or sorghum. There is no latent period for transmission to new host plants. After acquiring MDMV an aphid is able to transmit the virus within 15–30 minutes. Aphids do not retain MDMV after

molting In biology, moulting (British English), or molting (American English), also known as sloughing, shedding, or in many invertebrates, ecdysis, is the manner in which an animal routinely casts off a part of its body (often, but not always, an outer ...

. The virus can also be spread through the seed or mechanically by leaf rubbing of Johnson grass and sorghum. MDMV in the field is not typically transmitted by seed or mechanically, it is more prevalent in

greenhouses A greenhouse (also called a glasshouse, or, if with sufficient heating, a hothouse) is a structure with walls and roof made chiefly of transparent material, such as glass, in which plants requiring regulated climatic conditions are grown.These s ...

. Depending on the hybrid, most maize plants will show higher rates of disease when infected earlier in the growing stage. The pathogen itself is a

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