First report of Beet western yellows virus infecting Epiphyllum spp.
In 2015, an Epiphyllum hybrid with chlorotic spots was found in California, USA. Twelve more Epiphyllum hybrids (six with chlorotic ring spots, mottle, or mosaic and six asymptomatic) were obtained from a commercial nursery in New York, USA. These plants were tested by RT-PCR/PCR. Two potexviruses, Cactus virus X (CVX) and Zygocactus virus X (ZVX), were detected from three and one symptomatic hybrids, respectively. The California hybrid and seven New York hybrids (two symptomatic and five asymptomatic) tested positive for a badnavirus. However, no target viruses were detected in two of the seven symptomatic hybrids. To further investigate these observations, RNA sequencing was carried out which revealed the presence of Alternanthera mosaic virus, Beet western yellows virus (BWYV), and five new viruses (one ampelovirus, one badnavirus, two distinct carlaviruses, and one caulimovirus) in addition to CVX and ZVX. RT-PCR/PCR assay showed that the symptomless hybrid Professor Ebert was infected with five viruses (BWYV, an ampelovirus, two carlaviruses, and a caulimovirus), the most among the all hybrids. Twenty additional Epiphyllum hybrids were tested by RT-PCR, and BWYV was detected from hybrids Tele Ann with mottle symptom and Vista Sun without symptoms. Thus, BWYV was detected in three different hybrids of Epiphyllum spp., an observation validated by RT-PCR, sequencing, and graft transmission. This is thought to be the first report of BWYV in orchid cactus.