RESUMO
Presence of alternate hosts of plants is a great threat to the agriculture industry. Plants from several species growing in the papaya orchards affected by papaya sticky disease were examined for Papaya meleira virus (PMeV) infection causing this disease. The viral dsRNA was already detected in some plants from the family Poaceae or in watermelon. To identify new hosts of PMeV, we have collected 38 plant species belonging to 15 families of common weed species found in papaya-growing areas in México and used reverse-transcription PCR (RT-PCR) or quantitative real-time RT-PCR (RT-qPCR) for virus detection. We have detected the viral RNA in 11 species belonging to the families Acanthaceae, Fabaceae and Poaceae. Under experimental conditions, PMeV-Mx in Panicum hirsutum and Ruellia nudiflora inoculated weed species, showed that PMeV-Mx is able to replicate in plant cells of these species and spread in a systemic way. These results highlight the importance of weed species as potential virus reservoirs for PMeV-Mx Keywords: Papaya meleira virus; papaya sticky disease; Carica papaya; RT-PCR; TaqMan.
Assuntos
Carica , Vírus de Plantas , México , Doenças das Plantas , Vírus de Plantas/genética , RNA ViralRESUMO
Papaya meleira virus (PMeV) causes sticky disease in Carica papaya in Brazil and Mexico. Despite its economic importance and the need for effective phytosanitary control, it remains unknown whether any insect is the vector of this virus. The aim of this work was to identify potential insect vectors of the PMeV-Mexican variant (PMeV-Mx) and determine whether these potential vectors are capable of transmitting the virus. Adult insects were collected in papaya fields in the south-southeast region of Mexico and were identified morphologically and molecularly. Their abundance and frequency were determined, and quantitative reverse transcription polymerase chain reaction was performed to establish if they carried PMeV-Mx. The Cicadellidae family (Hemiptera) was the most diverse and abundant, and Empoasca papayae was the most abundant species and had the highest virus titers. PMeV-Mx transmission assays were conducted under controlled conditions using E. papayae on C. papaya 'Maradol'. E. papayae was a carrier of PMeV-Mx at 6 h after exposure, and its viral titer increased with time, peaking at 2.125 pg/µl of PMeV-Mx RNA from 20 ng/µl of cDNA, 5 days after exposure (dae). From 14 days after plants were exposed to insects, PMeV-Mx was detected and quantified in 100% of the evaluated papaya plants, whose viral RNA titer increased from 0.06 (21 dae) to 26.6 pg/µl of PMeV-Mx RNA (60 dae) from 20 ng/µl of cDNA. Three months later, these plants developed sticky disease symptoms, demonstrating that E. papayae is capable of transmitting PMeV-Mx to C. papaya 'Maradol'.