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.

The Virome of Babaco (Vasconcellea × heilbornii) Expands to Include New Members of the Rhabdoviridae and Bromoviridae

Babaco (Vasconcellea × heilbornii) is a subtropical species in the Caricaceae family. The plant is native to Ecuador and represents an important crop for hundreds of families. The objective of this study was to characterize, at the genomic level, two new babaco viruses identified by high-throughput sequencing. The viruses, an ilarvirus and a nucleorhabdovirus, were found in a symptomatic babaco plant from a commercial nursery in the Azuay province of Ecuador. The tripartite genome of the new ilarvirus, provisionally named babaco ilarvirus 1 (BabIV-1), is related to subgroup 3 ilarviruses, including apple mosaic virus, apple necrotic mosaic virus, and prunus necrotic ringspot virus as the closest relatives. The genome of the nucleorhabdovirus, provisionally named babaco nucleorhabdovirus 1 (BabRV-1), showed the closest relation with joa yellow blotch-associated virus and potato yellow dwarf nucleorhabdovirus. Molecular-based detection methods found BabIV-1 and BabRV-1 in 21% and 36%, respectively, of plants surveyed in a commercial babaco nursery, highlighting the importance of enforcing virus testing and nursery certification programs for babaco.