A unique virus complex causes Ageratum yellow vein disease

Area of Science:

• Plant virology
• Molecular biology
• Genetics

Background:

• Ageratum yellow vein virus (AYVV), a begomovirus, infects Ageratum conyzoides, causing yellow vein symptoms.
• Most begomoviruses possess bipartite genomes (DNA A and DNA B), but AYVV was initially thought to have only DNA A.

Purpose of the Study:

• To investigate the complete genomic requirements for AYVV-induced yellow vein disease in Ageratum conyzoides.
• To characterize the nature of the DNA components involved in the disease complex.

Main Methods:

• Molecular cloning and sequencing of viral DNA components.
• Co-infection experiments in Ageratum conyzoides.
• Analysis of DNA-protein interactions and replication dependency.

Main Results:

• Yellow vein disease results from a co-infection of AYVV DNA A and a novel circular DNA satellite, designated DNA beta.
• DNA beta is essential for efficient AYVV DNA A replication and systemic infection, acting as a DNA satellite.
• AYVV DNA A alone causes sporadic, asymptomatic infections with reduced DNA accumulation.

Conclusions:

• AYVV DNA A and DNA beta form a previously unrecognized disease-inducing complex in Ageratum conyzoides.
• DNA beta is crucial for the pathogenicity of AYVV, highlighting the importance of DNA satellites in begomovirus diseases.
• Nanovirus-like DNA 1 component is not essential for disease development.