Genomic Evolution of Tomato Spotted Wilt Virus and Its Resistance-Breaking Ability

Tomato spotted wilt virus (TSWV) continues to cause major losses in a wide range of crops due to its broad host range, the efficiency of its thrips vectors, and its capacity for rapid genomic diversification. This combination has complicated long-term disease management and has contributed to the repeated emergence of resistance-breaking (RB) strains in tomato, pepper, and other susceptible crops. While TSWV biology has been extensively investigated, the complex interplay among host range, vector biology, plant resistance, and RB evolution is often examined individually, neglecting its role as an integrated process. In this review, we aim to integrate current knowledge across these areas. We first describe the broad botanical range of TSWV and how movement among diverse hosts exposes viral populations to heterogeneous selection pressures. We then summarize key features of thrips-mediated transmission, including viral replication within vector tissues and the roles of vector immunity and associated microbes. Major resistance loci used in breeding, such as Sw-5, Sw-7, and Tsw, are reviewed, highlighting their mechanisms and limitations. We also analyze documented RB isolates from different regions, discussing the factors that appear to drive resistance breakdown, including genome reassortment, mutations in viral effectors such as NSs and NSm, environmental influences, and shifts in host or vector populations. Together, these perspectives demonstrate how interactions among TSWV, its plant hosts, and thrips vectors shape viral evolution in agricultural ecosystems. A clearer understanding of these processes will be essential for improving surveillance efforts and guiding the development of more sustainable and durable management strategies.