Incidence and characterization of viruses infecting orchids in São Paulo state, Brazil

Abstract

Orchids are susceptible to a variety of abiotic and biotic agents that can affect their development and decrease the quality of their flowers and leaves. Viruses are one of the most important biotic agents, with Cymbidium mosaic virus (CymMV) and Odontoglossum ringspot virus (ORSV) as the most prevalent and of greater economic importance worldwide. Similar to a survey of virus infection in orchids carried out 20 years ago by Freitas et al. in the state of São Paulo, a new evaluation was made incorporating molecular methodologies on a total of 385 samples collected from commercial growers. Commercial antisera against CymMV, ORSV, Cymbidium ringspot virus, Tomato spotted wilt virus and viruses in the genus Potyvirus were used in ELISA tests. PCRs were performed to detect Orchid fleck virus (OFV) and primers were designed to amplify the coding region of the CymMV and ORSV capsid proteins. The most prevalent virus was CymMV, present in 274 samples (71.16%), followed by ORSV and OFV, present in 61 and 11 samples (15.85% and 2,85%), respectively. CymMV and ORSV capsid protein genes showed high sequence conservation. Symptoms caused by CymMV and ORSV have a great variability and are commonly confused with abiotic factors, nutritional problems and phytotoxicity.

Genetic homogenisation of two major orchid viruses through global trade‐based dispersal of their hosts

“…There is also no indication that different genotypes of these viruses infect particular host species. This is in line with previous studies (Ajjikuttira et al, 2002;Moles, Delatte, Farreyrol, & Grisoni, 2007;Moraes et al, 2017) and suggests that there has been significant global transmission of these viruses.…”

“…There is also no indication that different genotypes of these viruses infect particular host species. This is in line with previous studies (Ajjikuttira et al, ; Moles, Delatte, Farreyrol, & Grisoni, ; Moraes et al, ) and suggests that there has been significant global transmission of these viruses. While acknowledging that only a partial fragment of the genome has been analyzed to determine the TMRCA, and that all but three of the sequences with confirmed sampling dates were obtained within a decade of the 2017 limit of this study (Table , ), both viruses appear to have ancestral genotypes that originated within the last 50 years.…”

“…Signs of disease include flower necrosis, chlorotic or necrotic patches on the leaves, and growth retardation (Ajjikuttira et al, ; Pearson & Cole, ; Zettler et al, ), though asymptomatic hosts can occur (Ajjikuttira et al, ; Zettler et al, ). Although the virus appears not to have a natural vector for transmission (Namba & Ishii, ), it is stable and easily spread through contaminated horticultural tools, media, and pollen (Lawson & Brannigan, ; Moraes, Krause‐Sakate, & Pavan, ). ORSV, a tobamovirus , also has a positive sense ssRNA genome of around 6.5 kb (Chng et al, ).…”

Exploring the Multifunctional Roles of Odontoglossum Ringspot Virus P126 in Facilitating Cymbidium Mosaic Virus Cell-to-Cell Movement during Mixed Infection

“…Among them, the odontoglossum ringspot virus (ORSV) and cymbidium mosaic virus (CymMV) are two of the most prevalent orchid-infecting viruses worldwide [ 18 , 19 ]. Single infection with ORSV or CymMV causes orchids to display growth defects and diminished flower quality, whereas co-infection results in synergistic effects that exacerbate disease severity, which can erode the orchid’s economic value [ 18 , 19 , 20 , 21 , 22 ] and even cause plant death [ 18 , 23 , 24 ].…”

Argonaute 5 family proteins play crucial roles in the defence against Cymbidiummosaicvirus and Odontoglossumringspotvirus in Phalaenopsisaphrodite subsp. formosana

“…Odontoglossum ringspot virus is a member of the genus Tobamovirus and has a genomic RNA of about 6,600 nt in length that encodes the 126K/183K proteins for viral replication, a movement protein, and a CP (Ryu & Park, 1995). The symptom caused by CymMV and/or ORSV usually varies in different species of orchids and is often confused with those induced by other factors, such as abiotic stress, malnutrition, and phytotoxicity (Moraes et al, 2017). The orchid species of Cymbidium, Cattleya, Epidendrum, and Phalaenopsis are considered to be more susceptible to CymMV infection.…”