First report of papaya meleira virus (PMeV) in Mexico

Abstract

Papaya meleira virus (PMeV), causal agent of meleira or sticky disease, is a double-stranded RNA (dsRNA) virus which has been previously reported only in Brazil. A study was carried out in order to verify the presence and occurrence of PMeV in Mexico. Latex samples from symptomatic and asymptomatic papaya fruits were collected in Quintana Roo state papaya orchards, where the first symptoms of PMeV were observed, and from 29 different municipalities located in ten papaya producer states in Mexico. A molecular protocol based on nucleic acid extraction was used for the diagnosis and a virus 12 Kb dsRNA distinctive band was observed in all PMeV infected plants. Around 46% of the evaluated plants were positive for this pathogen. Presence of the virus had been confirmed in seven states indicating the potential damage that PMeV could cause in the papaya crop in Mexico. The molecular analysis used allowed the diagnosis of infected plants without symptoms and facilitated the diagnosis in flowers and small papaya fruits also. The early diagnosis of PMeV will allow papaya producers to take appropriate and timely control measures. This is the first report of Papaya meleira virus in Mexico.

Genetic diversity studies of Papaya meleira virus

“…Soon afterwards, the disease was detected in the states of Pernambuco, Ceara and Rio Grande do Norte (Barbosa et al, 1998a,b). Outside Brazil, Mexico is the only other country where the disease has been reported (Perez-Brito et al, 2012).…”

“…Soon afterwards, the disease was detected in the states of Pernambuco, Ceara and Rio Grande do Norte (Barbosa et al, 1998a,b). Outside Brazil, Mexico is the only other country where the disease has been reported (Perez-Brito et al, 2012).The disease's typical symptoms are: excessive exudation of watery latex on the fruit surface, which oxidizes and gives the fruit a stained and sticky aspect; fruit malformation, uneven ripening and changes in the organolepctic properties, rendering it unmarketable.The PMeV genome composition and size are uncommon among plant viruses. PMeV has a double strand RNA (dsRNA) genome, approximately 12 Kb in length, packed into an isometric particle with ca.…”

“…The lack of tendency for isolates from the same region to group together was likely due to repeated introduction of multiple virus strains over the years, or due to constant movement of virus isolates through the movement of infested/infected seeds, seedlings or by the putative vector. Although the possibility of virus transmission by seed has never been properly investigated the recent detection of the virus in Mexico (Perez-Brito et al, 2012) suggests that PMeV can be transmitted by seed.…”

Early diagnosis of a Mexican variant of Papaya meleira virus (PMeV-Mx) by RT-PCR

“…Using nuclease treatments, it was shown that the 12-kb band was dsRNA. In addition, the disease was transmitted when the latex from diseased plants was injected into the apex of healthy plants (Perez-Brito et al, 2012). However, attempts to detect PMeV from Mexican orchards using the previously reported C05-3ꞌ primer failed (Araujo et al, 2007; Perez-Brito D, Tapia-Tussell R and Magaña A, personal communication and our own unpublished results).…”

“…Moreover, only a 669-base pair (bp) sequence encoding a fragment of a putative RNA-dependent RNA polymerase (RdRp) has been reported for this virus (Araújo et al, 2007). Meleira disease was initially described in the early 1980s in Brazil (Kitajima et al, 1993), and was recently detected in Mexican orchards (Perez-Brito et al, 2012). The first symptom is necrosis of the leaf tips, followed by spontaneous exudation of watery-translucent latex in immature fruits.…”