Occurrence, Distribution, and Population Structure of Schlumbergera Virus X in Dragon Fruit in Ecuador

The occurrence of Schlumbergera virus X (SchVX) in commercial dragon fruit fields in three provinces of Ecuador has been identified in this study. The virus was found in symptomatic and asymptomatic cladodes of the two major species (Hylocereus undatus and H. megalanthus) cultivated in the country. Symptoms in H. undatus included irregular and ring-shaped chlorotic spots that coalesce into large chlorotic patches along the cladodes, whereas small chlorotic spot symptoms on the cladodes were observed in H. megalanthus. Phylogenetic inferences based on 27 partial nucleotide sequences of the RNA-dependent RNA polymerase (RdRp) and three whole genome comparisons showed that Ecuadorean isolates from H. undatus and H. megalanthus share a most recent ancestor with isolates from Spain and Portugal. In addition, an SchVX isolate with a distinct genomic lineage was found in symptomatic H. polyrhizus plants from a single location, suggesting two independent virus introductions into the country.