Variability in Geminivirus Isolates Associated with Phaseolus spp. in Brazil

Area of Science:

• Plant virology
• Molecular biology
• Agricultural science

Background:

• Bean golden mosaic geminivirus (BGMV) is a major threat to common bean production in tropical and subtropical regions.
• BGMV isolates from Brazil (BGMV-BZ) show distinct characteristics compared to other BGMV-PR isolates.
• Geminiviruses cause significant agricultural losses, necessitating identification and characterization of new strains.

Purpose of the Study:

• To identify and characterize geminiviruses affecting beans and associated weeds in Brazil.
• To determine the genetic relatedness of Brazilian geminivirus isolates to known BGMV strains.
• To discover and name new geminivirus species based on molecular and biological properties.

Main Methods:

• Collection of symptomatic plant samples (beans, lima beans, Leonurus sibiricus) from Brazilian bean-growing areas.
• Amplification, cloning, and sequencing of viral DNA fragments (rep, common region, cp genes) using polymerase chain reaction (PCR).
• DNA sequence comparison and phylogenetic analysis to identify and classify geminivirus isolates.

Main Results:

• Bean samples contained geminiviruses nearly identical to the Brazilian BGMV-BZ isolate.
• A novel geminivirus species, lima bean golden mosaic virus (LBGMV-BR), was identified in lima bean samples.
• A distinct new geminivirus species, leonurus mosaic virus, was identified in Leonurus sibiricus.
• A mixed infection with abutilon mosaic geminivirus was detected in one sample.

Conclusions:

• The genetic diversity of geminiviruses in Brazil is greater than previously understood.
• LBGMV-BR and leonurus mosaic virus represent new species within the Geminiviridae family.
• Accurate identification of geminivirus species is crucial for effective disease management strategies in agriculture.