Cassava mosaic geminiviruses: actual knowledge and perspectives

Area of Science:

• Plant pathology
• Virology
• Molecular biology

Background:

• Cassava mosaic disease (CMD) is a major threat to cassava cultivation, primarily affecting Africa and the Indian subcontinent.
• Cassava mosaic geminiviruses (CMGs) are responsible for CMD, with diverse species and strains identified across different regions.
• The geographical distribution of CMD contrasts with the global cultivation of cassava, highlighting potential for spread.

Purpose of the Study:

• To review recent research on the CMD complex.
• To elucidate the molecular biology of CMGs in relation to other geminiviruses.
• To highlight the mechanisms CMGs employ to exploit host plants and cause disease.

Main Methods:

• Literature review of current research on CMD and CMGs.
• Analysis of molecular mechanisms, including gene silencing and suppressor protein evolution.
• Comparative study of CMGs with other geminiviruses.

Main Results:

• CMG recombination and pseudo-recombination generate novel, virulent strains and species, increasing biodiversity and epidemic potential.
• CMGs utilize suppressor proteins to counteract plant gene silencing defense mechanisms.
• Environmental factors and mixed infections with differential suppressor proteins can modulate disease severity and symptoms.

Conclusions:

• Understanding CMG molecular biology and evolution is crucial for managing CMD epidemics.
• CMGs exhibit sophisticated strategies to overcome host defenses, contributing to their virulence.
• Further research is needed to address the global threat of CMD to cassava production.