Phylogenetic Analysis of Turnip Mosaic Virus Isolates Based on Coat Protein and NIb Gene Sequences

Abstract

Phylogenetic analysis of Turnip mosaic virus (TuMV) isolates was conducted using coat protein and NIb gene sequences to elucidate genetic diversity, evolutionary relationships, and population structure. Field samples exhibiting mosaic, leaf deformation, and stunting symptoms were collected from Brassica crops across diverse agroecological regions. Viral RNA was extracted and subjected to RT-PCR amplification targeting coat protein and NIb genomic regions, followed by sequencing and comparative analysis with reference isolates. Phylogenetic reconstruction revealed clustering of TuMV isolates into distinct clades corresponding to previously reported phylogroups, indicating significant genetic variability within regional populations. Coat protein sequences provided initial resolution of isolate grouping, while NIb gene analysis offered higher phylogenetic resolution and improved discrimination among closely related strains. Evidence of recombination events and sequence divergence suggested ongoing viral evolution driven by host adaptation and geographic separation. Genetic variation among isolates was partially associated with host species and regional distribution, reflecting complex epidemiological patterns. The study highlights the importance of multilocus sequence analysis for accurate characterization of TuMV populations. These findings contribute to improved understanding of virus evolution and spread in Brassica cropping systems and support the development of durable resistance strategies and effective virus management programs based on molecular surveillance.