Lamin-like Proteins Negatively Regulate Plant Immunity through NAC WITH TRANSMEMBRANE MOTIF1-LIKE9 and NONEXPRESSOR OF PR GENES1 in Arabidopsis thaliana

Abstract

Nuclear lamins are involved in multiple biological processes in metazoan cells. The proteins of the CROWDED NUCLEI (CRWN) family are considered lamin-like candidates in Arabidopsis, although the functions of these proteins are largely unknown. In this article we show that crwn1 crwn2 double mutant displays an enhanced resistance against virulent bacterial pathogens, and both virulent bacteria and salicylic acid (SA) induce transcription of CRWN1 gene as well as proteasome-mediated degradation of CRWN1 protein. We also show that CRWN1 interacts with NAC WITH TRANSMEMBRANE MOTIF1-LIKE9 (NTL9), a NAC transcription factor involved in plant immunity. The interaction between CRWN1 and NTL9 enhances the binding of NTL9 to the promoter of the PATHOGENESIS-RELATED1 (PR1) gene, and inhibits PR1 expression. Further genetic experiments indicated that the defense-related phenotypes of crwn1 crwn2 double mutant are dependent on NONEXPRESSOR OF PR GENES1 (NPR1), a transcriptional cofactor of PR1. These findings revealed a regulatory network composed of lamin-like protein CRWN1, NTL9, and NPR1 for the regulation of PR1 expression.

The Lamin-Like LITTLE NUCLEI 1 (LINC1) Regulates Pattern-Triggered Immunity and Jasmonic Acid Signaling

“…Upon Pst DC3000 infection, they found no difference in linc1 and linc4 single mutants but enhanced resistance in linc1/2 and linc1/4 double mutants. Guo et al (2017) were able to observe lower SA levels in the linc1 linc2 double mutant than in wild-type plants after inoculation with Psm ES4326, whereas Choi et al (2019) found elevated SA levels only in linc1/2 double mutants. In the linc1/2 and linc1/4 double mutants, the same authors reported enhanced levels of cell death FIGURE 5 | LINC1 modulates the glucosinolate biosynthesis pathway.…”

“…The Arabidopsis genome contains four LINC genes which have been extensively documented regarding their roles in regulating nuclear structure, chromatin organization, and nuclear size (Dittmer et al, 2007;Sakamoto and Takagi, 2013;Wang et al, 2013;Guo and Fang, 2014;Grob et al, 2014). Recent work addressed the role of the LINC gene family in biological processes such as seed germination (Zhao et al, 2016) and plant immunity (Zhao et al, 2016;Guo et al, 2017;Choi et al, 2019). In the latter study, Guo et al reported that among the single and double linc mutant lines tested, they observed a slightly enhanced pathogen resistance phenotype in the single linc1-1 mutant against infection by the virulent Psm ES4326 pathogen, but a much FIGURE 4 | LINC1 modulates JA accumulation and signaling.…”

“…Arabidopsis quadruple linc mutants are not viable (Dittmer et al, 2007;Sakamoto and Takagi, 2013;Wang et al, 2013), but mutations in both LINC1 and LINC4, but not in LINC2 and LINC3, can change nuclear size and the shape of differentiated cells (Dittmer et al, 2007;Dittmer and Richards, 2008). However, except for recent reports on the role of LINC1 and LINC3 in seed germination (Zhao et al, 2016), and enhanced disease phenotype in the linc1 linc2 double mutant (Guo et al, 2017), the functions of LINC proteins have not been further characterized.…”

“…Furthermore, LINC1 also interacts with the NAC transcription factor NTL9 and plays a role in suppressing the plant immune response towards the virulent pathogen Pseudomonas syringae pv. maculicola (Psm) ES4326 (Guo et al, 2017). Guo et al also reported a role for pathogens and SA in inducing LINC1 degradation, which interacts with NTL9 and SNI1 to inhibit PR1 transcription (Guo et al, 2017).…”

“…maculicola (Psm) ES4326 (Guo et al, 2017). Guo et al also reported a role for pathogens and SA in inducing LINC1 degradation, which interacts with NTL9 and SNI1 to inhibit PR1 transcription (Guo et al, 2017).…”