Occurrence of Yellowing Viruses (CABYV, CCYV, and MABYV) in Cucurbit Crops in Korea and Development of a Multiplex RT-PCR Assay for Simultaneous Detection

Abstract

This study investigated the occurrence of yellowing viruses in Korean cucurbit crops and developed a multiplex reverse transcription-polymerase chain reaction (RT-PCR) assay for their simultaneous detection. Between 2020 and 2024, symptomatic leaf samples from melon, cucumber, and watermelon were analyzed nationwide. Cucurbit aphid-borne yellows virus (CABYV) and cucurbit chlorotic yellows virus (CCYV) were widely distributed. The average detection rates in symptomatic samples of melon were 48.8% for CABYV and 9.2% for CCYV, and in cucumber, 26.8% for CABYV and 17.1% for CCYV. In watermelon, based on two years of symptomatic sampling, CABYV and CCYV were detected at 5.8% and 6.8%, respectively. Notably, despite a 4.5% national average, melon aphid-borne yellows virus (MABYV) was detected at high rates in symptomatic watermelon samples from Jeonbuk (up to 58.5% in 2023). Because these viruses induce visually indistinguishable symptoms and frequently cause mixed infections, accurate identification is crucial for vector-specific disease management. Therefore, a multiplex RT-PCR assay was developed to simultaneously detect CABYV, CCYV, and MABYV in a single reaction, successfully differentiating single and mixed infections with a detection limit of a 10-3 dilution.