![]() This short review describes some of the molecular diagnostic tools currently developed, which include end-point RT-PCR and TaqMan RT-qPCR. A multidisciplinary team of scientists united by the USDA SCRI project entitled Combating rose rosette disease: Short and long term approaches is developing molecular and serological diagnostic tools for rapid and sensitive detection of RRV. Currently, neither enzyme-linked immunosorbent assay nor a rapid lateral flow immunoassay is commercially available for testing RRV. Rose rosette emaravirus is a recently characterized virus and little is known about its diversity and biology. Early identification requires a highly reliable, specific, and sensitive detection assay for either detection or confirmation of the rose rosette disease. The only effective strategy for disease management is early identification and eradication of the infected plants, thereby limiting the spread of RRV. Diagnosis of rose rosette disease in early stages could be misleading because of its resemblance to symptoms caused by herbicide damage or other plant viruses. The disease ultimately leads to the death of the plant in 1–2 years ( Amrine, 2002). Some of the symptoms include excessive thorniness, witches’ broom, red pigmentation which does not disappear as the plant matures, and excessive lateral shoot growth. The symptoms of rose rosette disease are highly variable and depend on the rose cultivar, growth stage, and environmental conditions ( Windham et al., 2014a, 2014b). For example, RNA1, RNA2, RNA3, and RNA4 encode an RNA-dependent RNA polymerase (RdRp), a glycoprotein, a nucleocapsid, and a movement protein, respectively, whereas RNA5, RNA6, and RNA7 have unknown function ( Babu et al., 2016a Di Bello et al., 2015 Laney et al., 2011). ![]() The RRV virion is reported to contain seven genomic RNA segments, some of which encode known functions. Rose rosette emaravirus has a multipartite genome enclosed by a double membrane-bound body of 120–150 nm in diameter ( Gergerich and Kim, 1983 Gergerich et al., 1983). The mites do not fly but passively move long distances via air currents, spreading to nearby roses and infecting rose plantings with RRV ( Epstein and Hill, 1999 Windham et al., 2014a). The virus is transmitted by the eriophyid mite species Phyllocoptes fructiphilus ( Amrine et al., 1988 Laney et al., 2011) and by grafting ( Amrine et al., 1988). Rose rosette disease is associated with RRV (genus Emaravirus), a single-stranded negative-sense RNA virus ( Laney et al., 2011). Also, the disease has been identified on cultivated roses in the midwest, portions of the northeast, and a few western states in the United States. The disease affects many rose species and cultivars, and has become widespread in the north-central, south-central, and southeast regions. Among the diseases of roses, rose rosette disease has become the most devastating, causing economic losses to nurseries, landscapes, and gardeners ( Stanley, 2013). In the United States, the total sales of shrub rose’s value was 204 million U.S. Roses are one of the most important ornamental flowering shrubs grown worldwide. This review introduces an overall view of the different diagnostic tools developed, which are reliable, highly sensitive, and can be easily implemented for detection and identification in laboratories providing diagnostic services and confirmation of RRV-infected samples. Department of Agriculture (USDA) Specialty Crop Research Initiative (SCRI) project sponsorship, several diagnostic tools including end-point reverse transcription-polymerase chain reaction (RT-PCR) and RT-qPCR assays targeting single and multiple genes targets were developed for routine diagnostics. RRV is only a recently characterized virus and hence limits the diagnostic tools available for its early detection. Highly reliable, specific, and sensitive detection assays are thus required to test and confirm the presence of RRV in suspected plant samples. The only strategy available for disease management is early identification and eradication of the infected plants. Rose rosette emaravirus (RRV, genus Emaravirus), the causal agent of rose rosette disease, is the topmost pathogen of concern for the rose industry in the United States.
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