Geminivirus coat protein gene replacement alters insect specificity

Area of Science:

• Plant Virology
• Molecular Biology
• Insect Vector Transmission

Background:

• Geminiviruses, like African cassava mosaic virus (ACMV) and beet curly top virus (BCTV), possess bipartite genomes and cause significant crop damage.
• Understanding the mechanisms of geminivirus replication, movement, and transmission is crucial for developing effective control strategies.
• The coat protein plays a role in virion structure and is a candidate for determining vector specificity.

Purpose of the Study:

• To investigate the role of the coat protein in geminivirus transmission specificity.
• To construct and characterize chimeric geminiviruses with exchanged coat protein genes.
• To determine if the coat protein dictates the interaction with insect vectors.

Main Methods:

• Construction of chimeric geminivirus clones by replacing the ACMV coat protein gene with the BCTV coat protein gene.
• Inoculation of Nicotiana benthamiana plants with chimeric constructs and parental viruses.
• Analysis of viral gene expression, encapsidation of viral DNA, and transmission by the leafhopper vector Circulifer tenellus.

Main Results:

• Chimeric viruses were infectious and produced ACMV-like symptoms, albeit with delayed onset and symptom remission.
• The BCTV coat protein was expressed and encapsidated both ACMV DNA components when inserted in the correct orientation.
• The leafhopper vector transmitted the chimeric virus and BCTV, but not ACMV, demonstrating coat protein-mediated vector specificity.

Conclusions:

• The coat protein of a geminivirus is the primary determinant of its transmission specificity by insect vectors.
• Swapping coat proteins can alter the vector range of geminiviruses.
• This study provides critical insights into the molecular basis of plant virus-vector interactions.