• Proceedings of the Plant Resources Society of Korea Conference
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• 2019.04a
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• pp.54-54
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• 2019

Apple (Malus domestica) is one of the most economically important fruits in Korea. But virus infection has decreased sustainable production of apple and caused the serious problems such as yield loss and poor fruit quality. Virus or viroid infection including Apple chlorotic leaf spot virus (ACLSV), Apple stem pitting virus (ASPV), Apple stem grooving virus (ASGV), Apple mosaic virus (ApMV) and Apple scar skin viroid (ASSVd) has been also reported in Korea. In many cases, apple is infected with virus and viroid with no specific symptoms, the damage caused by the virus are unaware significantly. In our research, we tried to eliminate viruses in the rootstock for the disease-free seedlings of the apple dwarfing rootstock M.9 and M.26. The method of virus elimination was meristem culture, heat($37^{\circ}C$, 6weeks) treatment and chemistry($Ribavirin^{(R)}$) treatment. The analytical methods commonly used for the detection of virus is Enzyme-linked Immuno-Sorbent Assay(ELlSA) and Reverse Transcription-polymerase Chain Reaction(RT-PCR). RT-PCR method was more 30% sensitive than ELISA method. Efficiency of method eliminate virus appeared meristem method > heat treatment > chemistry treatment. The higher acquisition rate of disease-free seedlings is 30~40% on meristem treatment. In meristem treatment, the apple dwarfing rootstock M.9 gained infection ratio of ACLSV, ASPV and ASGV were 45%, 60% and 50% respectively. In the apple dwarfing rootstock M.26, infection ratio of ACLSV, ASPV and ASGV were 40%, 55%, 55%, respectively. Based on our results, it was found that most effective method of disease-free seedlings apple dwarfing rootstocks was by meristem treatment than heat method and chemistry treatment.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.122-123
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• 2003

Apple stem grooving virus (ASGV) belongs to Capillovirus and infects pome fruits. Transmission mode of ASGV is known by grafting and mechanical inoculation into susceptible hosts, not by any other natural vectors. But we have observed the spread of ASGV in the field without mechanical inoculation or grafting. Transmission seems to be occurred from tree-to-tree and tree-to-susceptible herbaceous plants along but not across ditches in the field. In order to ascertain this possibility, various fungi were isolated and cultured from ASGV-infected plants and 69 isolates were characterized. By means of RNA dot-blot hybridization and PCR analysis, 3 isolates were sorted out for further studies. The isolates were identified to Tataromyces sp. and belonged to Phenicillium by morphological characteristics and molecular markers. As an experimental host, 10 kidney beans (Phaseolus vulgaris) were screened and Kyunggi-5 was selected for virus amplification and symptom development. Kyunggj-5 infected by fungi which seemed to carry ASGV showed the typical disease symptoms and viral coat protein genes were detected from all tested plants. To confirm the Koch's rule, fungi cultured from inoculation origins of kidney bean were grown on PDA media and re-inoculated to hosts. The fungi isolated from inoculation origins induced the typical disease symptoms on hosts. However virus free fungi did not induce any symptom on the experimental hosts. This bioassay showed that these typical symptoms were caused by virus, not fungi.

• Research in Plant Disease
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• v.23 no.4
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• pp.355-362
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• 2017

The 4 viruses, the Apple chlorotic leaf spot virus (ACLSV), Apple stem pitting virus (ASPV), Apple stem grooving virus (ASGV), and Apple mosaic virus (ApMV) and 1 viroid, Apple scar skin viroid (ASSVd) are known major viral pathogens of apple trees in Korea. Infection degree of the 5 viral pathogens in the commercial nursery trees of major apple cultivars, 'Hongro', 'Fuji' and bud mutation of 'Fuji' was investigated. Infection ratio of the ACLSV, ASPV and ASGV for scion of an apple cultivar 'Hongro' were 100%, 81.3% and 100%, respectively. On the other hand, no infection for either ApMV and ASSVd detected. For the root stock of the cultivar, infection ratio of ACLSV, ASPV and ASGV showed 87.5%, 81.3% and 100% as well as ApMV and ASSVd were 12.5% and 6.3%, respectively. From the scion of apple cultivars 'Fuji' and bud mutation of 'Fuji', infection ratio of ACLSV, ASPV and ASGV showed 86.7%, 86.7% and 100%, respectively. Whereas, no infection for either ApMV or ASSVd detected. From the root stock of the cultivars, infection ratio of ACLSV, ASPV and ASGV showed 86.7%, 93.3% and 93.3% as well as ApMV and ASSVd were 12.5% and 6.3%, respectively. Result of our study indicates that most of commercial nursery apple trees were supplied with multiple infections by apple viruses causing potential losses for apple growers and, henceforth, agricultural policy for supply of the virus-free trees should be employed as soon as possible.

• Research in Plant Disease
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• v.26 no.3
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• pp.144-158
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• 2020

Quantitative reverse transcription PCR is used for gene expression analysis as the accurate and sensitive method. To analyze quantification of gene expression changes in apple plants, 10 housekeeping genes (ACT, CKL, EF-1α, GAPDH, MDH, PDI, THFs, UBC, UBC10, and WD40) were evaluated for their stability of expression during infection by Apple stem grooving virus (ASGV) or in cold-stress apple plant buds. Five reference-gene validation programs were used to establish the order of the most stable genes for ASGV as CKL>THFs>GAPDH>ACT, and the least stable genes WD40CKL>UBC10, and the least stable genes were ACT

• Journal of Plant Biotechnology
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• v.43 no.3
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• pp.391-396
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• 2016

In this study, in vitro-cultured 'Mansoo' pear (Pyrus pyrifolia L.) plants infected with Apple stem grooving virus (ASGV) were used for testing the efficiency of the virus elimination methods. The shoot tips cut from infected plants were treated by thermotherapy ($37^{\circ}C$), cold therapy ($4^{\circ}C$), chemotherapy with ribavirin, and combination of these methods. Treatment periods were 2, 4, and 8 weeks, and concentrations of ribavirin were 20 and $40mg{\cdot}L^{-1}$. The efficiency of ASGV elimination was evaluated by reverse transcription polymerase chain reaction. The shoot survival rate was the highest at 100% after cold therapy, chemotherapy, and combination of two methods, while the rate was the lowest at 33.3% after thermotherapy for 2 weeks. The shoot survival rate after chemotherapy decreased gradually as the treatment period was prolonged. The ASGV elimination rate was the highest at 100% after ribavirin treatment at a concentration of $40mg{\cdot}L^{-1}$ and combination of ribavirin treatment and thermotherapy for 2 weeks, whereas the ASGV elimination rate after cold therapy was the lowest at 16.7%. However, the efficiency of ASGV elimination was enhanced up to 43.3% by the combination of cold therapy and ribavirin treatment. The efficiency of ASGV elimination for all treatments was increased as the treatment period was prolonged. Based on these results, we suggest that ribavirin treatment at a concentration of $20mg{\cdot}L^{-1}$ for 4 weeks or at a concentration of $40mg{\cdot}L^{-1}$ for 2 weeks combined with shoot tip culture was efficient for the elimination of ASGV from pear.

• Research in Plant Disease
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• v.25 no.1
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• pp.43-47
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• 2019

Apple chlorotic leaf spot virus (ACLSV), Apple stem pitting virus (ASPV), Apple stem grooving virus (ASGV), and Apple scar skin viroid (ASSVd) are economically important viruses that infect pear tree species worldwide. To evaluate the prevalence of these viruses in Korea, we investigated infection degree of three viruses and one viroid for the commercial nursery trees of the pear cultivars, Niitaka, Chuwhang, Wonwhang, and Whasan in 2017 and 2018. The results showed that the infection ratio of ACLSV, ASPV, ASGV, and ASSVd for the scion of pear cultivar Niitaka was 10%, 45%, 77%, and 50%, respectively. From the scion of pear cultivar Chuwhang, infection ratios of ASPV, ASGV, and ASSVd were found to be 70%, 50%, and 60%, respectively. From the scion of pear cultivar Whasan, infection ratios of ACLSV, ASPV, ASGV and ASSVd were found to be 40%, 60%, 93%, and 20%, respectively. From the root stock of pear cultivar Wonwhang, infection ratios of ACLSV, ASPV, ASGV, and ASSVd showed 28%, 57%, 100%, and 14%, respectively. ASGV had the highest recorded infection rate, and ACLSV was characterized by the lowest infection rate. The mixed infection ratio of Niitaka, Chuwhang, Whasan, and Wonwhang was 45%, 60%, 70%, and 85%, respectively.

• Research in Plant Disease
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• v.16 no.3
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• pp.326-330
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• 2010

Three pome fruit viruses, Apple chlorotic leaf spot virus (ACLSV), Apple stem grooving virus (ASPV) and Apple stem pitting virus (ASGV) were detected in pear trees (Pyrus pyrifolia) using double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) in Ansung, Naju and Ulsan provinces of Korea. Infection rate of three viruses was 35.2% from 452 leaf samples of the three cultivars of pear trees. Also, each of three viruses was detected by reverse transcription polymerase chain reaction (RT-PCR) for a limited number of samples. Infection rate of three viruses was 86.3% from 233 leaf samples of the three pear cultivars. The virus infection rates by RT-PCR were much higher than ELISA. ASGV was prevailing on pear with 74.2%, whereas ASPV and ACLSV were found in 34.8% and 0.4% of tested samples, respectively. Symptoms caused by ASGV showed black spots of infected Niitaka cultivar leaves. The ACLSV, ASPV and ASGV isolates showed 83~94% sequence identity at a nucleotide level to other pome fruit virus isolates when analyzed by NCBI BLAST. Pome fruit viruses occurring in pear were ACLSV, ASPV and ASGV. This is the first report of pear trees infected ASPV in Korea.

• The Plant Pathology Journal
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• v.38 no.5
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• pp.533-540
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• 2022

Thunberg fritillary (Fritillaria thunbergii), a perennial used in traditional Chinese herbal medicine, is a members of the family Liliaceae. The degeneration of germplasm is a severe problem in the production of Fritillaria thunbergii var. chekiangensis. However, no information about viral infections of F. thunbergii var. chekiangensis has been reported. In this study, we sequenced the small RNAs of F. thunbergii var. chekiangensis from leaves and bulbs, and viruses were identified using a phylogenetic analysis and BLAST search for sequence. In addition, multiplex reverse transcriptase-polymerase chain reaction (RT-PCR) was used to rapidly detect viruses in this variety. Our study first reported that five viruses infected F. thunbergii var. chekiangensis. Among them, fritillary virus Y (FVY), lily mottle virus (LMoV), Thunberg fritillary mosaic virus (TFMV), and hop yellow virus (HYV) had been reported in F. thunbergii, while apple stem grooving virus was first reported in the genus Fritillaria. A multiplex RT-PCR method was developed to rapidly test the four viruses FVY, LMoV, TFMV, and HYV in F. thunbergii var. chekiangensis. Our results provide a better understanding of the infection of F. thunbergii var. chekiangensis by viruses and a basic reference for the better design of suitable control measures.