Molecular Characterization and Partial Genome Sequencing of Lettuce Mosaic Virus Isolates in Protected Cultivation

Abstract

Lettuce Mosaic Virus (LMV), a member of the genus Potyvirus, is one of the most economically important viral pathogens affecting lettuce production worldwide, particularly under protected cultivation systems where intensive cropping favors rapid disease spread. Infected plants commonly exhibit mosaic patterns, chlorosis, leaf distortion, stunted growth, and reduced market quality, resulting in significant economic losses. The present study was conducted to investigate the molecular characteristics and partial genome sequences of LMV isolates associated with lettuce crops grown under protected cultivation conditions. Field surveys were carried out in commercial greenhouse and net-house production systems, and symptomatic lettuce plants were collected for laboratory analysis. Total RNA was extracted from infected leaf tissues and subjected to reverse transcription polymerase chain reaction (RT-PCR) using LMV-specific primers targeting conserved genomic regions. Amplified products were sequenced and analyzed using BLAST and phylogenetic methods to determine genetic identity, sequence variability, and evolutionary relationships among the isolates. Partial genome sequencing further enabled comparison of nucleotide and amino acid similarities with previously reported LMV strains from different geographic regions. The results confirmed the presence of LMV in symptomatic lettuce samples collected from protected cultivation systems. Sequence analysis revealed high genetic similarity among local isolates and previously reported LMV strains, although detectable sequence variation indicated ongoing viral evolution and adaptation. Phylogenetic analysis grouped the isolates into distinct clusters associated with known LMV lineages, suggesting possible dissemination through infected seed material and intensive crop production practices. The findings provide important insights into the molecular diversity and genomic characteristics of LMV populations affecting protected lettuce cultivation. Early molecular diagnosis and genome-based characterization are essential for improving disease surveillance, understanding virus epidemiology, and developing effective management strategies. The study supports the implementation of integrated disease management practices, including the use of virus-free seed, strict sanitation, and regular monitoring to minimize LMV-associated losses in protected lettuce production systems.