Mutations in nuclear pore complex promote osmotolerance in Arabidopsis by suppressing the nuclear translocation of ACQOS and its osmotically induced immunity

We have previously reported a wide variation in salt tolerance among accessions and identified , encoding a nucleotide-binding leucine-rich repeat (NLR) protein, as the causal gene responsible for the disturbance of acquired osmotolerance induced after mild salt stress. is conserved among Arabidopsis osmosensitive accessions, including Col-0. In response to osmotic stress, it induces detrimental autoimmunity, resulting in suppression of osmotolerance, but how triggers autoimmunity remains unclear. Here, we screened ( ) mutants from EMS-mutagenized Col-0 seeds and isolated the mutant. In comparison with the wild type (WT), this mutant had acquired osmotolerance and decreased expression levels of pathogenesis-related genes. It had a mutation in a splicing acceptor site in ( ), which encodes a component of the nuclear pore complex. A mutant with a T-DNA insertion in acquired osmotolerance similar to The WT gene complemented the osmotolerant phenotype of . We evaluated the acquired osmotolerance of five mutants of outer-ring s and found that , , and , but not or , showed acquired osmotolerance. We examined the subcellular localization of the GFP-ACQOS protein and found that its nuclear translocation in response to osmotic stress was suppressed in . We suggest that NUP85 is essential for the nuclear translocation of ACQOS, and the loss-of-function mutation of NUP85 results in acquired osmotolerance by suppressing ACQOS-induced autoimmunity in response to osmotic stress.