Exploring the virome of Vasconcellea x heilbornii: the first step towards a sustainable production program for babaco in Ecuador

The virome of babaco (Vasconcellea x heilbornii) —a non-traditional fruit crop native to Ecuador— was investigated by high-throughput sequencing (HTS) on plants obtained from a commercial nursery. Six virus-like sequences were detected, including the full length of papaya ringspot virus (PRSV) and an RNA-dependent-RNA-polymerase (RdRp) sequence with homology to papaya virus Q. Three RNA sequences were found with homology, respectively, to apple latent spherical virus (genus Cheravirus, 71% nt identity), cherry leaf roll virus (genus Nepovirus, 54% nt identity) and Citrullus lanatus cryptic virus (genus Deltapartitivirus, 66% nt identity); whereas a DNA pararetrovirus-like sequence with homology to citrus endogenous pararetrovirus (58% nt identity) was also detected. RT-PCR-based virus surveys on a total of 284 samples collected from three provinces revealed that the partitivirus- and pararetrovirus-like sequences were present in 100% of tested plants; whereas the other virus sequences were detected in up to 68% of plants and were associated with different symptoms. This work provides information on the occurrence and prevalence of PRSV and five additional virus-like sequences in babaco, a vegetatively propagated crop, supporting the need for a virus-free certification program.