Detection and survey of coffee ringspot virus in Brazil

Coffee ringspot virus (CoRSV) a member of the proposed genus "Dichorhavirus", was surveyed on commercial and research farms spanning an area responsible for the majority of Coffea arabica production in Brazil. Virus-infected plants were found at one hundred percent of locations (n = 45) sampled. All cultivars, regardless of cherry color, were found to serve as hosts, suggesting that there is limited resistance in commercially employed germplasm. Reverse transcription PCR analysis revealed that the virus is contained within symptomatic lesions, with little systemic spread throughout leaves. Phylogenetic analysis based on the ORF1 (nucleocapsid) gene identified a strong geo-spatial relationship among isolates, which clustered into three clades. Despite low genetic diversity among isolates, variation in symptom expression was observed in the experimental host Chenopodium quinoa. Our analyses support the hypothesis that the spread of CoRSV is constrained by the clonal expansion of thelytokous populations of Brevipalpus phoenicis. The widespread occurrence of this virus suggests that it is much more prevalent than previously thought.