Orchids, members of the family Orchidaceae, are highly evolved monocotyledonous flowering plants, comprising 900 genera and 2500–3500 species [1]. They are one of the largest families to exhibit huge diversities in flower size, shape and colors, and are famous for their longevity and enchantingly beautiful appearance. They are, therefore, economically popular ornamental cut-flowers and potted floricultural crops worldwide. Due to their high economic value, new varieties with specific or improved floral traits and desired characteristics, such as flowering time and prolonged vase-life, are constantly being generated to meet the market demand.During cultivation, orchid plants are highly threatened by many phytopathogens, especially the viruses. Due to their high susceptibilities, the cultivation of resistant orchids has become a big challenge to the industry. To date, at least 30 different viruses have been reported to infect orchids, including Cymbidium mosaic virus (CymMV) [2], Odontoglossum ringspot virus (ORSV) [3], Orchid fleck virus (OFV) [4], Cucumber mosaic virus (CMV) [5], Dendrobium vein necrosis closterovirus (DVNV) [6], and Tomato spotted wilt virus (TSWV) [7]. Although these viruses may infect orchids of a specific species, some of these viruses (e.g. CymMV) may produce different diseases in different species.