Characterization of the Roles of SGT1/RAR1, EDS1/NDR1, NPR1, and NRC/ADR1/NRG1 in Sw-5b -Mediated Resistance to Tomato Spotted Wilt Virus

The tomato gene confers resistance to tomato spotted wilt virus (TSWV) and encodes a nucleotide-binding leucine-rich repeat (NLR) protein with an N-terminal Solanaceae-specific domain (SD). Although our understanding of how recognizes the viral NSm elicitor has increased significantly, the process by which activates downstream defense signaling remains to be elucidated. In this study, we used a tobacco rattle virus (TRV)-based virus-induced gene silencing (VIGS) system to investigate the roles of the SGT1/RAR1, EDS1/NDR1, NPR1, and NRC/ADR1/NRG1 genes in the -mediated signaling pathway. We found that chaperone SGT1 was required for function, but co-chaperone RAR1 was not. -mediated immune signaling was independent of both EDS1 and NDR1. Silencing , which is a central component in SA signaling, did not result in TSWV systemic infection in -transgenic plants. Helper NLR NRCs (NLRs required for cell death) were required for -mediated systemic resistance to TSWV infection. Suppression of NRC2/3/4 compromised the resistance. However, the helper NLRs ADR1 and NRG1 may not participate in the signaling pathway. Silencing ADR1, NRG1, or both genes did not affect -mediated resistance to TSWV. Our findings provide new insight into the requirement for conserved key components in -mediated signaling pathways.