Role of the Sw5 Gene Cluster in the Fight against Plant Viruses.

The Sw5 gene cluster furnishes robust resistance to Tomato spotted wilt virus in tomato, which has led to its widespread applicability in agriculture. Among the five orthologs, Sw5b functions as a resistance gene against a broad-spectrum tospovirus and is linked with tospovirus resistance. However, its paralog Sw5a has been recently implicated in providing resistance against Tomato leaf curl New Delhi virus, broadening the relevance of the Sw5 gene cluster in promoting defense against plant viruses. We propose that plants have established modifications within the homologs of R genes that permit identification of different effector proteins and provide broad and robust resistance against different pathogens through activation of the hypersensitive response and cell death.