Putative members of the Arabidopsis Nup107-160 nuclear pore sub-complex contribute to pathogen defense

In eukaryotic cells, transduction of external stimuli into the nucleus to induce transcription and export of mRNAs for translation in the cytoplasm is mediated by nuclear pore complexes (NPCs) composed of nucleoporin proteins (Nups). We previously reported that Arabidopsis MOS3, encoding the homolog of vertebrate Nup96, is required for plant immunity and constitutive resistance mediated by the de-regulated Toll interleukin 1 receptor/nucleotide-binding/leucine-rich repeat (TNL)-type R gene snc1. In vertebrates, Nup96 is a component of the conserved Nup107-160 nuclear pore sub-complex, and implicated in immunity-related mRNA export. Here, we used a reverse genetics approach to examine the requirement for additional subunits of the predicted Arabidopsis Nup107-160 complex in plant immunity. We show that, among eight putative complex members, beside MOS3, only plants with defects in Nup160 or Seh1 are impaired in basal resistance. Constitutive resistance in the snc1 mutant and immunity mediated by TNL-type R genes also depend on functional Nup160 and have a partial requirement for Seh1. Conversely, resistance conferred by coiled coil-type immune receptors operates largely independently of both genes, demonstrating specific contributions to plant defense signaling. Our functional analysis further revealed that defects in nup160 and seh1 result in nuclear accumulation of poly(A) mRNA, and, in the case of nup160, considerable depletion of EDS1, a key positive regulator of basal and TNL-triggered resistance. These findings suggest that Nup160 is required for nuclear mRNA export and full expression of EDS1-conditioned resistance pathways in Arabidopsis.