Microviruses

Microviruses are a group of small, single-stranded DNA viruses belonging to the family Geminiviridae. They are characterized by their distinctive geminate (twin) particles, which are actually two single virions joined together along their longitudinal axes. These viruses are known for their ability to infect a wide range of plants, causing significant agricultural damage.

The genome of a microvirus typically consists of a single molecule of circular, positive-sense single-stranded DNA, ranging in size from approximately 2.7 to 3.1 kilobases. They encode a limited number of proteins, usually including replication-associated proteins and proteins involved in encapsidation and transport. Replication occurs in the nucleus of the host plant cell and involves a rolling-circle mechanism.

Microviruses are transmitted from plant to plant primarily by insect vectors, most commonly whiteflies. Upon acquisition by the vector, the virus is inoculated into a new host plant during feeding. This efficient mode of transmission contributes to their widespread distribution and impact on crops such as tomatoes, beans, and cotton.

The symptoms of microvirus infection can vary depending on the specific virus and host plant, but often include stunting, leaf curling, yellowing (chlorosis), and distortion. These symptoms can lead to reduced yield and quality of agricultural produce. Control strategies often focus on managing the insect vectors and using resistant plant varieties.