Transmission of the umbra-like Papaya virus Q in Ecuador and its association with meleira-related viruses from Brazil

Abstract

Papaya virus Q (PpVQ) is an umbra-like virus found in papaya plantings of Ecuador. A most recent study conducted in Brazil has reported the presence of a virus with 70% nucleotide identity to PpVQ. The Brazilian virus was shown to act synergistically with Papaya meleira virus (PMeV) to induce a devastating disorder known as papaya meleira. This finding prompted us to investigate epidemiology aspects of PpVQ, especially its transmission and potential involvement with meleira like symptoms in Ecuador. Three out of ten plants inoculated with ‘viruliferous’ whiteflies (Bemisia tabaci) tested positive for PpVQ; whereas no mechanical or seed transmission was observed. Surveys using a multiplex RT-PCR assay for the simultaneous detection of PpVQ, PMeV and Papaya ringspot virus (PRSV) revealed that PpVQ is found most commonly in co-infections with PRSV, but also in single infections in asymptomatic plants. PMeV, on the other hand, was not detected in any of the tested plants. Interestingly, two virus sequences with homology to PpVQ and PMeV, respectively, were found in leaf samples from babaco (Vasconcellea x heilbornii, syn. Carica pentagona), a sub-tropical relative of papaya native to Ecuador, highlighting the importance of implementing a surveillance scheme for papaya meleira disease in Ecuador as a preventative management and control strategy.