First Detection of Cucurbit Aphid-Borne Yellows Virus (CABYV) in Watermelon Fields Using Molecular Diagnostics

Abstract

Cucurbit Aphid-Borne Yellows Virus (CABYV) was investigated in watermelon (Citrullus lanatus L.) fields to determine its occurrence and confirm its presence using molecular diagnostic approaches. Field surveys conducted in major cucurbit-growing areas revealed symptoms including interveinal chlorosis, leaf yellowing, reduced vine vigor, and stunted plant growth, often associated with aphid infestation. Leaf samples collected from symptomatic and asymptomatic plants were analyzed using reverse transcription polymerase chain reaction (RT-PCR) with CABYV-specific primers targeting the coat protein gene. Amplification products confirmed the presence of CABYV in symptomatic watermelon samples, representing the first molecular detection of this virus in the surveyed production areas. Sequencing of representative isolates showed high similarity with global CABYV isolates, confirming their identity and indicating limited genetic divergence. Phylogenetic analysis grouped the detected isolates within the established CABYV clade, closely related to strains reported from other cucurbit-growing regions, suggesting possible introduction through infected planting material or vector-mediated spread. No significant host-specific differentiation was observed, although minor sequence variation indicated early-stage diversification. Disease incidence was positively associated with aphid population density and warmer seasonal conditions that favor vector activity. The study highlights the importance of molecular surveillance for early detection of emerging viral threats in cucurbit production systems. These findings emphasize the need for integrated management strategies, including aphid vector control, use of virus-free planting material, and regular monitoring to prevent further spread and minimize yield losses in watermelon cultivation systems.