A Survey on the Occurrence and Seed Transmission of Cherry Virus A in Sweet Cherry in Bulgaria

Cherry virus A (CVA) is widespread in sweet cherry ( Prunus avium L.) across Europe, North and South America, Asia, and Oceania. However, until now, the presence of CVA in Bulgaria has not been reported. This study focused on two critical aspects: the occurrence of CVA in sweet cherry in Bulgaria's two main fruit production areas—the South Central and Southeast regions—and the probability of its vertical (seed) transmission. CVA was identified through virus-specific amplification of the coat protein (CP) gene, and in vitro embryo culture was used to assess vertical transmission. Our results indicate that CVA is present in sweet cherry in both surveyed regions, detected in 23.5 and 21.4% of the tested samples from the South Central and Southeast regions, respectively. Phylogenetic analysis of the CP nucleotide sequence revealed that Bulgarian CVA isolates were clustered into two groups based on their geographical origin. Moreover, CVA was detected in seeds collected from naturally infected trees and their seed progenies. To the best of our knowledge, this is the first report of CVA in Bulgaria and the first evidence of its vertical transmission in sweet cherry.