Inverse modulation of the NIK-mediated antiviral signaling and antibacterial immunity in plants by RNA effectors
E. FONTES (1) (1) Universidade Federal de Vicosa, Brazil

NIK1 (NSP-interacting kinase 1) is an Arabidopsis leucine-rich repeat receptor-like kinase (LRR-RLK), which was first identified as a virulence target of the bipartite begomovirus nuclear shuttle protein (NSP). NSP suppresses NIK1 activity through specific binding to the kinase domain and enhances begomoviruses pathogenicity to their hosts. Although NIK1 is structurally similar to the plant immune sensor BAK1, which is a key regulator in plant immunity to bacterial pathogens via association with multiple immune sensors, the NIK1-mediated defenses do not resemble BAK1-activated signaling cascades. Recently, we demonstrated that the constitutive activation of NIK1 leads to global translation suppression and translocation of the downstream component RPL10 to the nucleus, where it interacts with a MYB-like protein, LIMYB (L10-interacting Myb domain-containing protein), to fully down-regulate translational machinery genes. LIMYB overexpression represses ribosomal protein genes at the transcriptional level, resulting in protein synthesis inhibition, decreased viral mRNA association with polysome fractions and enhanced tolerance to begomoviruses. Therefore, the antiviral immunity function of NIK1 relies on global translation suppression. Here we show that the constitutive activation of NIK1 suppresses PAMP-immune responses, as a distinct branch of the NIK-mediated signaling. This was explained by an inverse modulation of the plant immune sensor complex BAK1/NIK1 to bacterial and viral infections. We further showed that the trade off between NIK1-mediated antiviral signaling and antibacterial immunity is directed by RNA effectors derived from begomovirus infection in Arabidopsis.


Abstract Number: C14-1
Session Type: Concurrent