Because Cnidium officinale is susceptible to viral infection, this study investigated the proportion of virus elimination and plant growth after treatments with thermotherapy and chemotherapy. In the thermotherapy group, Apple stem grooving virus (ASGV) and Cnidium vein yellowing virus–2 (CnVYV-2) were significantly reduced in 33℃ treatment. However, Cnidium vein yellowing virus–1 (CnVYV-1) was not affected by any of the four temperature treatments, and Cucumber mosaic virus (CMV) did not show the tendency to eliminate viruses according to temperature treatment. In the investigation of in vitro growth characteristics, plants were not significantly affected by temperature treatments. In the chemotherapy group, 40 mg･L-1 ribavirin treatment was the most effective in eliminating viruses. Different ribavirin concentrations (0 to 40 mg･L-1) did not significantly influence the in vitro plant survival rate. ASGV was completely eliminated with combined thermotherapy and chemotherapy (T29R20 and T29R40). Although the combined thermotherapy and chemotherapy treatment did not affect in vitro plant growth, it significantly influenced root development. The results indicate that thermotherapy, chemotherapy, and the combined treatment effectively eliminated these four viruses (ASGV, CnVYV-1, CnVYV-2, and CMV) without producing any major problems in C. officinale.

Plant viral diseases are incurable and reduce fruit yield and quality, causing economic losses. Damages vary depending on the virus-host combination, virulence, and cultivar susceptibility. Therefore, the fundamental way to prevent virus damage is to cultivate virus-free plants. Thermotherapy, cold therapy, chemotherapy and cryotherapy combined with microshoot tip culture are used to eliminate fruit tree viruses. This review describes fruit viral diseases and summarizes the current elimination methods. Next-generation sequencing (NGS) has also been used to identify and diagnosis new fruit crop viruses. Therefore, studies are needed to optimize elimination methods for NGS-identified viruses.

Background : Rehmannia glutinosa Libosch. is a perennial herb belonging to family Scrophulariaceae. It is also considered as a valuable medicinal plant in Asia including Korea, China and Japan because of its anti-anemic, anti-pyretic, anti-inflammatory and anti-senescence effects. Unfortunately it is difficult to propagate seeds due to poor seed viability and low propagation rate. Therefore, this plant is propagated vegetatively, but its vegetative propagation increases the incidence of virus infections in commercial fields, which can induce the production loss critically. So we have tried to compare the efficacy of virus elimination from R. glutinosa by thermotherapy, chemotherapy and shoot tip culture to find an optimal micropropagation for healthy and virus-free plant production. Methods and Results : For virus elimination, thermotherapy (heat treatment at 37℃ for 4 weeks), chemotherapy (addition into medium with antiviral agent) and shoot tip culture (meristem culture) were accomplished. After treatments, RT-PCR and ELISA methods were used for detection of three viruses including tobacco mosaic virus (TMV), cucumber mosaic virus (CMV), broad bean wilt virus (BBWV). Conclusion : Efficiency of virus elimination was enhanced up to 59% in shoot tip culture, however, lowest at 5 - 10% after chemotherapy using antiviral agent (ribavirin). Most samples were verified to have multiple virus infection. From these results, we can suggest that combination treatment of shoot tip culture and thermotherapy may be more effective for the elimination of major viruses from R. glutinosa.

Sweet potato infected with a viral disease (SPFMV) showed irregular chlorotic patterns, so called feathering associated with faint or distinct ring spots that have purple-pigmented borders. SPFMV was eliminated from sweet potato plants using meristem tip culture. MS medium supplemented with BAP (2mg/L) and NAA (0.05 mg/L) was used for shoot proliferation and 1/2 MS medium for rooting of the plants. Highest percentage of regenerated plants (60%) was obtained from the optimum size (0.3-0.5mm) meristem tips. Of these, 60% plants were found negative for SPFMV by RT-PCR. Virus detection by RT-PCR was found to be a reliable method. Meristem-tip culture to produce SPFMV-free quality sweet potato and virus detection by RT-PCR is an efficient, time saving and reliable method for production of SPFMV-free tissue culture raised plants.