Advances in Small Isometric Multicomponent ssDNA Viruses Infecting Plants

Area of Science:

• Plant Virology
• Molecular Plant Pathology
• Genomics

Background:

• Multicomponent single-stranded DNA (ssDNA) plant viruses, classified under the family Nanoviridae, cause economically significant diseases like bunchy top, yellowing, and dwarfing in plants.
• These viruses, primarily found in tropical and subtropical regions, are persistently transmitted by aphid vectors and are not sap or seed transmissible.

Purpose of the Study:

• To review the classification, genomic structure, and infectivity of Nanoviridae family viruses.
• To highlight the essential role of specific genomic components in the disease cycle of these viruses.

Main Methods:

• Review of existing literature on Nanoviridae viruses, focusing on their taxonomy, genome organization, and transmission.
• Analysis of studies demonstrating the infectivity of viral genomic components, particularly for Faba bean necrotic stunt virus (FBNSV).

Main Results:

• The Nanoviridae family comprises Nanovirus and Babuvirus genera, with genomes consisting of multiple circular ssDNA molecules.
• Up to 12 DNA components have been identified, encoding proteins such as replication initiator protein (Rep), coat protein, and movement protein.
• Infectivity has been demonstrated for only two nanoviruses; FBNSV requires a specific set of eight ssDNA components for disease induction and progeny production.

Conclusions:

• The infectivity of Babuvirus genomic components remains unproven.
• A master Rep protein controls the replication of other genomic components within the Nanoviridae family.
• Understanding the infectivity requirements of these ssDNA viruses is crucial for developing effective disease management strategies.