FIGURE 2.

Topology of Sw-5 proteins encoded by paralogs from the Sw-5 gene cluster and orthologs collected from tomatoes susceptible to orthotospoviruses. The upper schematic encompasses the Sw-5 proteins of S. peruvianum. So far, there are only functional studies on Sw-5a and Sw-5b. The latter directly interacts with NSm (orthotospovirus cell-to-cell movement protein), which activates orthotospovirus resistance. On the contrary, Sw-5a is unable to recognize NSm as avirulence (avr)-determinant. The lower schematic shows two Sw-5 proteins found in tomato cultivars susceptible to orthotospoviruses. The most conserved homolog of Sw-5a and Sw-5b, named Sw-5a^S, contains a mutation in its nucleotide-binding (NB) domain that halts hypersensitive response (HR) triggering. Apart from this, Sw-5a^S cannot recognize NSm as avr-determinant. Sw-5f has been first reported interacting with an effector (SPRYSEC-19) of nematode Globodera rostochiensis that inhibits HR triggered by several resistance proteins.