Molecular Characterization and Coat Protein Analysis of Zucchini Tigré Mosaic Virus Isolates in Cucurbit Greenhouses

Abstract

Severe mosaic, mottling, chlorosis, leaf deformation, and fruit discoloration symptoms were observed in cucurbit crops cultivated under greenhouse conditions, indicating possible infection by Zucchini tigré mosaic virus (ZTMV). Symptomatic leaf samples collected from commercial cucurbit greenhouses were subjected to molecular detection and coat protein characterization to determine the identity and diversity of the virus isolates. Total RNA extracted from infected tissues was analyzed using reverse transcription polymerase chain reaction (RT-PCR) with virus-specific primers targeting conserved genomic regions. Amplification of the expected DNA fragments confirmed the presence of ZTMV in symptomatic cucurbit plants, whereas healthy control samples tested negative. Sequencing and comparative nucleotide analysis revealed high genetic similarity among local isolates and previously reported ZTMV isolates from other geographic regions. Phylogenetic analysis grouped the obtained isolates within established ZTMV lineages, demonstrating close evolutionary relationships while also indicating minor sequence variability among greenhouse populations. Detailed analysis of the coat protein gene identified conserved amino acid motifs associated with viral infectivity, host interaction, and systemic movement within cucurbit hosts. Variations in coat protein sequences among isolates suggested ongoing genetic diversification likely influenced by intensive greenhouse cultivation and continuous host availability. Disease incidence was markedly higher in greenhouses with dense vector populations and inadequate sanitation practices, conditions favorable for rapid virus spread. Infected plants exhibited reduced vigor, impaired fruit development, and substantial decline in marketable yield and quality. Accurate molecular characterization and coat protein analysis of ZTMV isolates are essential for improving diagnostic reliability, understanding viral evolution, and supporting the development of effective disease management strategies.