Evaluation of genetic diversity of tomato spotted wilt virus (TSWV) NSs gene region isolates at geographical level

One of the most significant plant protection problems that adversely affect agricultural production is diseases caused by viruses, as there are no direct and rapid control methods. Tomato spotted wilt virus (TSWV), which is known to cause major losses in vegetable production and is quite common in the Mediterranean basin, is one of these viruses. In reducing the prevalence of the agent, control of vector insects and use of resistant varieties are the primary parameters. In this study, the genetic diversity of the partial Non-Structural NSs gene, which produces a putative silencing suppressor protein of TSWV, was investigated at the level of geographical populations. A total of 325 isolates were clustered from Eastern European, European Mediterranean, Asian, African, and American populations and geographic genetic diversity analyses were performed. Phylogenetic analyses revealed 2 major phylogroups (Clade I and II). Isolates reported from Asia and Africa were clustered only in Clade II, while other isolates were distributed in both groups. Haplotype network analyses revealed that the isolates had genotypes partially related to their geography. In support of these results, molecular variance analyses (AMOVA) showed that there were significant results for both proposals when applied between and within geographic groups. The findings highlight that TSWV has experienced different evolutionary processes in geographical regions, that the virus spreads along different genetic lines in regions, that local genotypes may dominate in regions and potentially adapt more quickly, and that local plant health institutions should increase regional quarantine measures and isolation strategies, and that it is important to take these genetic differences into account in order for the control to be more effective and targeted.