Molecular interaction between two cassava geminiviruses exhibiting cross-protection

Area of Science:

• Plant Virology
• Molecular Plant Pathology
• Virus-Host Interactions

Background:

• Geminivirus mixed infections are increasing, potentially leading to recombination and new epidemics.
• Previous work identified mixed infections of ACMV and EACMCV causing severe cassava mosaic disease in Cameroon.

Purpose of the Study:

• To investigate the potential for recombination between ACMV and EACMCV.
• To understand the replication dynamics of ACMV and EACMCV components during mixed infections.
• To explore the induction of resistance and cross-protection mechanisms.

Main Methods:

• Assessing reassortment of DNA-A and DNA-B components between ACMV and EACMCV.
• Monitoring replication and spread of viral DNA components in mixed infections.
• Evaluating symptom development and plant recovery in infected Nicotiana benthamiana.

Main Results:

• Reassortment of ACMV and EACMCV DNA-A and DNA-B components did not yield viable recombinants.
• ACMV DNA-A replicated and spread independently of its DNA-B in the presence of EACMCV components, and vice versa.
• ACMV DNA-A induced resistance to both ACMV and EACMCV, leading to delayed or absent symptoms and recovery from EACMCV infection.

Conclusions:

• The inability of ACMV and EACMCV DNA-A to trans-replicate the heterologous DNA-B component prevents viable recombinant formation.
• ACMV DNA-A confers a non-specific resistance to both ACMV and EACMCV, consistent with cross-protection.
• Understanding these interactions is crucial for managing geminivirus diseases in cassava.