Editing Plant virus (section)

== Structure ==

[[File:Molecules-23-02311-g001.png|thumb|Structural comparison of some plant viruses]]

Viruses are so small that they can only be observed under an [[electron microscope]]. The structure of a virus is given by its coat of [[proteins]], which surround the viral [[genome]]. Assembly of viral particles takes place [[Self-organization#Self-organization in biology|spontaneously]].

Over 50% of known plant viruses are [[rod-shaped]] ([[flexuous]] or rigid). The length of the particle is normally dependent on the genome but it is usually between 300 and 500 [[nanometers|nm]] with a [[diameter]] of 15–20&nbsp;nm. Protein subunits can be placed around the [[circumference]] of a circle to form a disc. In the presence of the viral genome, the discs are stacked, then a tube is created with room for the [[nucleic acid]] genome in the middle.<ref>{{cite journal |last1=Parvez |first1=Mohammad Khalid |title=Geometric architecture of viruses |journal=World Journal of Virology |date=25 August 2020 |volume=9 |issue=2 |pages=5–18 |doi=10.5501/wjv.v9.i2.5 |doi-access=free|pmid=32923381 |pmc=7459239 }}</ref>

The second most common structure amongst plant viruses are [[isometric (disambiguation)|isometric]] particles. They are 25–50&nbsp;nm in diameter. In cases when there is only a single coat protein, the basic structure consists of 60 T subunits, where T is an [[integer]]. Some viruses may have 2 coat proteins that associate to form an [[icosahedron|icosahedral]] shaped particle.

There are three genera of ''[[Geminiviridae]]'' that consist of particles that are like two isometric particles stuck together.

A few number of plant viruses have, in addition to their coat proteins, a [[cell membrane|lipid envelope]]. This is derived from the plant cell membrane as the virus particle [[viral shedding|buds]] off from the [[Cell (biology)|cell]].