The reliability of DAS-ELISA for detecting tomato spotted wilt orthotospovirus in leaf and root tissue from symptomatic and asymptomatic peanut plants

Thrips-transmitted tomato spotted wilt orthotospovirus (TSWV) causes spotted wilt disease in peanut. Double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) is commonly used to detect TSWV. Previous studies detected higher rates of TSWV infection in peanut root tissue than leaf tissue using DAS-ELISA and suggested that root tissue might be a better sink for TSWV than leaf tissue. Nevertheless, the mechanism(s) responsible for higher TSWV detection rates in root tissue than leaf tissue in these studies remains unknown. Asymptomatic TSWV infection has been documented in peanut, and it is not clear if TSWV detection in asymptomatic plants is affected by the type of tissue tested. To address these questions, TSWV detection using DAS-ELISA in leaf and root tissue from symptomatic and asymptomatic plants was cross-validated with reverse transcription polymerase chain reaction (RT-PCR) and quantitative RT-PCR (qRT-PCR). TSWV was also quantitated by qRT-PCR in leaf and root tissue. TSWV was detected by DAS-ELISA, RT-PCR, and qRT-PCR at similar rates in leaf and root tissue from symptomatic plants and in leaf tissue from asymptomatic plants. However, TSWV was detected at a significantly higher rate in root tissue from asymptomatic plants using DAS-ELISA compared to RT-PCR and qRT-PCR.