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The plant-specific NAC ( NAM, ATAF1,2, CUC2) transcription factors play significant roles in diverse physiological processes. In this study, we determined the regulation of a stress-related tomato ( Solanum lycopersicum) NAC1 ( Sl NAC1) transcription factor at both the transcriptional and the post-translational level., The Sl NAC1 protein was found to be stable in the presence of proteasome-specific inhibitor MG132 or MG115 and ubiquitinated in plant cells, suggesting that the Sl NAC1 is subject to the ubiquitin-proteasome system-mediated degradation. Deletion analysis identified a short segment of 10 amino acids (aa261-270) that was required for ubiquitin-proteasome system-mediated degradation, among which two leucine residues (L268 and L269) were critical for the protein instability of Sl NAC1. Fusion of the degron ( Sl NAC1191-270) containing these 10 amino acids to green fluorescent protein was found to be sufficient to trigger the degradation of the fusion protein., In addition, the Sl NAC1 gene is strongly upregulated during Pseudomonas infection, while repression of the NAC1 ortholog in Nicotiana benthamiana resulted in enhanced susceptibility to Pseudomonas bacteria., These results suggest that rapid upregulation of the NAC1 gene resulting in more protein production is likely one of the strategies plants use to defend themselves against pathogen infection. [ABSTRACT FROM AUTHOR]

In this study, we show that the potato ( Solanum tuberosum ) pattern recognition receptor (PRR) NEMATODE-INDUCED LEUCINE-RICH REPEAT (LRR)-RLK1 (StNILR1) functions as a dual receptor, recognizing both nematode-associated molecular pattern ascaroside #18 (Ascr18) and plant hormone brassinosteroid (BR) to activate two different physiological outputs: pattern-triggered immunity (PTI) and BR response. Ascr18/BR-StNILR1 signaling requires the coreceptor potato BRASSINOSTEROID INSENSITIVE 1-ASSOCIATED RECEPTOR KINASE 1 (StBAK1) and perception of either ligand strengthens StNILR1 interaction with StBAK1 in plant cells. Significantly, the parasitically successful potato cyst nematode ( Globodera pallida ) utilizes the effector RHA1B, which is a functional ubiquitin ligase, to target StNILR1 for ubiquitination-mediated proteasome-dependent degradation, thereby countering Ascr18/BR-StNILR1-mediated PTI in potato and facilitating nematode parasitism. These findings broaden our understanding of PRR specificity and reveal a nematode parasitic mechanism that targets a PTI signaling pathway., Competing Interests: Competing interests statement:The authors declare no competing interest.

The potato (Solanum tuberosum) cyst nematode Globodera pallida induces a multinucleate feeding site (syncytium) in potato roots as its sole source of nutrition. Here, we demonstrate that the G. pallida effector RING-H2 finger A1b (RHA1B), which is a functional ubiquitin ligase, interferes with the carbon catabolite repression 4 (CCR4)-negative on TATA-less (NOT) deadenylase-based RNA metabolism machinery that regulates syncytium development in G. pallida-infected potato. Specifically, RHA1B targets the CCR4-associated factor 1 (CAF1) and StNOT10 subunits of the CCR4-NOT complex for proteasome-mediated degradation, leading to upregulation of the cyclin gene StCycA2 involved in syncytium formation. The StCAF1 subunit of CCR4-NOT recruits the RNA binding protein StPUM5 to deadenylate StCycA2 mRNA, resulting in shortened poly-A tails of StCycA2 mRNA and subsequently reduced transcript levels. Knockdown of either subunit (StCAF1 or StNOT10) of the CCR4-NOT complex or StPUM5 in transgenic potato plants resulted in enlarged syncytia and enhanced susceptibility to G. pallida infection, which resembles the phenotypes of StCycA2 overexpression transgenic potato plants. Genetic analyses indicate that transgenic potato plants overexpressing RHA1B exhibit similar phenotypes as transgenic potato plants with knockdown of StNOT10, StCAF1, or StPUM5. Thus, our data suggest that G. pallida utilizes the RHA1B effector to manipulate RNA metabolism in host plants, thereby promoting syncytium development for parasitic success., (© The Author(s) 2024. Published by Oxford University Press on behalf of American Society of Plant Biologists. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

The plant-specific NAC (NAM, ATAF1,2, CUC2) transcription factors play significant roles in diverse physiological processes. In this study, we determined the regulation of a stress-related tomato (Solanum lycopersicum) NAC1 (SlNAC1) transcription factor at both the transcriptional and the post-translational level. The SlNAC1 protein was found to be stable in the presence of proteasome-specific inhibitor MG132 or MG115 and ubiquitinated in plant cells, suggesting that the SlNAC1 is subject to the ubiquitin-proteasome system-mediated degradation. Deletion analysis identified a short segment of 10 amino acids (aa261-270) that was required for ubiquitin-proteasome system-mediated degradation, among which two leucine residues (L268 and L269) were critical for the protein instability of SlNAC1. Fusion of the degron (SlNAC1(191-270) ) containing these 10 amino acids to green fluorescent protein was found to be sufficient to trigger the degradation of the fusion protein. In addition, the SlNAC1 gene is strongly upregulated during Pseudomonas infection, while repression of the NAC1 ortholog in Nicotiana benthamiana resulted in enhanced susceptibility to Pseudomonas bacteria. These results suggest that rapid upregulation of the NAC1 gene resulting in more protein production is likely one of the strategies plants use to defend themselves against pathogen infection., (© 2012 The Authors. New Phytologist © 2012 New Phytologist Trust.)