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ARS Home » Pacific West Area » Corvallis, Oregon » Horticultural Crops Research Unit » Research » Publications at this Location » Publication #321829
Title: Detection and partial genome sequence of a new umbra-like virus of papaya discovered in Ecuador

Author
item QUITO-AVILA, D - Centro De Investigaciones Biotecnologicas Del Ecuador
item ALVAREZ, R - Centro De Investigaciones Biotecnologicas Del Ecuador
item IBARRA, M - Centro De Investigaciones Biotecnologicas Del Ecuador
item Martin, Robert

Submitted to: European Journal of Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/30/2015
Publication Date: 5/13/2015
Citation: Quito-Avila, D.F., Alvarez, R.A., Ibarra, M.A., Martin, R.R. 2015. Detection and partial genome sequence of a new umbra-like virus of papaya discovered in Ecuador. European Journal of Plant Pathology. 143:199–204. https://doi.org/10.1007/s10658-015-0675-y.
DOI: https://doi.org/10.1007/s10658-015-0675-y

Interpretive Summary: In an effort to understand mild leaf symptoms on papaya trees that exhibit typical fruit symptoms, double-stranded RNA (dsRNA) was extracted from papaya leaves infected with Papaya ringspot virus (PRSV). An unusual 4000 base band was observed in addition to the presumed PRSV-associated 10,000 band. After cloning and sequencing, a partial sequence of the 4000 base pair dsRNA revealed homology to genomes of several members of the genus Umbravirus. Detection primers showed that the virus was present in two out of three papaya producing provinces in Ecuador included in this study. The virus was found in 31% of 150 symptomatic trees sampled from Los Rios province and 5% of 50 symptomatic trees sampled from Santa Elena province and was not found in any of 50 symptomatic trees from Santo Domingo province. The virus was only detected in 2% of 50 symptomless and PRSV-free trees that were sampled. Mechanical and aphid inoculations failed to transmit the virus under controlled conditions. The presence of a luteovirus, commonly found associated with umbraviruses, was not confirmed in plants infected with the new virus using universal luteovirus primers. The mild symptoms were not associated with a mixed infection of the new umbra-like virus and PRSV, but rather the mild symptoms are probably the result of growers removing symptomatic trees based on typical leaf symptoms and inadvertently selecting for a strain that caused mild leaf symptoms.

Technical Abstract: Double-stranded RNA (dsRNA) extractions from papaya leaves infected with Papaya ringspot virus (PRSV) revealed the presence of an unusual 4kb band, in addition to the presumed PRSV-associated 10kb band. Partial sequence of RT-PCR products from the 4kb dsRNA revealed homology to genomes of several members of the genus Umbravirus. Detection primers showed that the virus was present in two out of three papaya producing provinces in Ecuador included in this study. The virus was found in up to 31% of symptomatic PRSV-infected trees compared to 2% in symptomless and PRSV-free plants. Mechanical and aphid inoculations failed to transmit the virus under controlled conditions. The presence of a luteovirus, commonly found associated with umbraviruses, was not confirmed in plants infected with the new virus using universal luteovirus primers.