Nanjing Agricultural University Nanjing, Jiangsu, China (People's Republic)
Tomato spotted wilt virus (TSWV), a segmented negative-strand RNA virus, poses a significant threat to agricultural production. The Sw-5b gene, which recognizes the TSWV movement protein NSm, is the most effective resistance gene for controlling TSWV in tomato cultivation. However, natural resistant tomato resources exhibit extreme resistance to TSWV, while transgenic materials carrying Sw-5b alone show comparatively weaker resistance. Previous studies have identified a Sw-5 gene cluster in resistant tomatoes, comprising five Sw-5 genes (Sw5a, Sw5b, Sw5c, Sw5d, and Sw5e), with only Sw5b conferring broad-spectrum resistance to tospoviruses. Here, we report the discovery of a sixth Sw-5 gene, Sw5b-like, in certain resistant tomato varieties, which also activates resistance by recognizing the TSWV NSm protein. Using CRISPR-Cas9 to specifically knock out Sw5b, we observed a significant reduction in extreme resistance, though Sw5b-like retained partial resistance to TSWV. This finding demonstrates that the co-evolution of two functional Sw-5 genes in resistant tomatoes synergistically confers extreme resistance to the virus. Our results provide a novel case for understanding NLR-mediated resistance mechanisms and offer a critical foundation for developing strategies to control plant viral diseases.
