First report of tomato spotted wilt virus infecting lobelia in South Korea

Authors: CHUNG, BONG-NAM - National Institute Of Horticultural & Herbal Science (NIHHS); CHOI, SEUNG-KOOK - National Institute Of Horticultural & Herbal Science (NIHHS); CHOI, SENA - National Institute Of Horticultural & Herbal Science (NIHHS); CHO, IN-SOOK - National Institute Of Horticultural & Herbal Science (NIHHS); Hammond, John; LIM, HYOUN-SUB - Chungnam National University

Submitted to: Journal of Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/22/2023
Publication Date: 7/18/2023
Citation: Chung, B., Choi, S., Choi, S., Cho, I., Hammond, J., Lim, H. 2023. First report of tomato spotted wilt virus infecting lobelia in South Korea. Journal of Plant Pathology. https://doi.org/10.1007/s42161-023-01445-7.
DOI: https://doi.org/10.1007/s42161-023-01445-7

Interpretive Summary: Virus infection of crop plants frequently causes losses of yield and quality, and identification of the causal virus is necessary to aid control. Virus-like symptoms were observed on lobelia plants growing in Gyeonggi province in Korea. Scientists determined that the symptoms were caused by two distinct isolates of tomato spotted wilt virus (TSWV), which had not previously been detected in this host in South Korea. The genomic differences between the two isolates suggested that a genetic reassortment had taken place during mixed infection with an unknown isolate in a prior host. In addition to infecting lobelia, this virus causes damage to other crops such as tomatoes, peppers, and other ornamental plants; therefore, it is important to control the insect vector of this virus (thrips) to limit field spread. This knowledge will be useful to growers of susceptible crops, and to plant disease diagnostic laboratories and extension agents.

Technical Abstract: In January 2022, virus-like symptoms of foliar chlorotic mottle, distortion and stunted growth (Online Resource 1) were observed in approximately 80% of a commercial field planted with ten thousand lobelias ‘Sweet Springs Blue’ and ‘Hot Bavaria’ in Gyeonggi province, South Korea. To identify the causal virus, symptomatic leaves were tested separately for tomato spotted wilt virus (TSWV) and impatiens necrotic spot virus (INSV) using ImmunoStrip assays (Agdia, Elkhart, IN), producing positive results only for TSWV. To confirm the presence of TSWV, total RNA was isolated from 16 symptomatic plants (8 Sweet Springs Blue; 8 Hot Bavaria) and reverse transcription-polymerase chain reaction (RT-PCR) was performed using virus-specific primers, TSWV777-F/R (Chung et al., 2021). RT-PCR products of the expected sizes (777 bp) were obtained from 14 samples (6 Sweet Springs Blue; 8 Hot Bavaria) and sequenced. The complete genome sequences of TSWV from symptomatic lobelia ‘Sweet Springs Blue’ and ‘Hot Bavaria’ were determined using TSWV-specific primers (Lee et al., 2011). The sequences from ‘Sweet Springs Blue’ (TSWV-SS; accession no. LC685923, LC685924 and LC685925) showed highest nt identity of 99.25%, 99.39% and 99.21% with TSWV-L, M and S RNAs (MT643236, OM154970 and MN854654), respectively, while those from ‘Hot Bavaria’ (TSWV-HB; LC698324, LC698325 and LC698326) showed highest nt identity of 98.43%, 99.41% and 99.25% with TSWV L, M and S RNAs (MF159049, OM154970 and MN854654), respectively. Whereas TSWV-SS and TSWV-HB M and S RNAs each had highest identity to OM154970 and MN854654, their L RNAs were divergent (Online Resource 2), suggesting reassortment. To our knowledge, this is the first report of TSWV infecting lobelia in South Korea. TSWV is transmitted by thrips and causes serious damage in various crops such as tomato, pepper and ornamental plants in South Korea. It is important to control vector populations to prevent field spread of TSWV.