Project description:Roots are very important at different stages of plant growth, and the formation of lateral roots is essential for strengthening the roots and absorbing nutrients from the soil. Therefore, it is of great significance to uncover the molecular mechanism of lateral root development in plants for understanding plant life process and improving plant adaptation to environment. As an important post-translational modification of small protein types, small ubiquitin-like modifier is involved in many biological processes such as transcriptional regulation, cell cycle regulation, and immune response. SUMO E3 ligase plays a key role in the SUMO process and plays an important role in plant growth and development. In Arabidopsis thaliana, SIZ1 encodes a SUMO E3 ligase, which plays an important role in plant life, especially in stress response. We analyzed the expression sites of SIZ1 and found that it was obviously expressed in lateral roots, especially in the nucleus of lateral roots. Previous studies on SIZ1 mainly focused on biological stress and abiotic stress, but the molecular mechanism of SIZ1 regulating lateral roots has not been studied. We propose a mechanism by which hemicylation of LBD29 mediated by SIZ1 regulates the occurrence of lateral roots in Arabidopsis Thaliana, which provides a new idea and direction for subsequent research on lateral root development.
Project description:SIZ1, a major plant SUMO E3 ligase, has diverse roles in development and immunity. Although loss-of-function studies have positioned SIZ1 as a negative immune regulator, the pleiotropic effects of its broad substrate repertoire may obscure its core function. Here we report that SIZ1 overaccumulation unexpectedly triggers robust pro-immune responses and cell death, dependent on its E3 ligase activity. We demonstrate that SIZ1 functionally converges on the MOS4-Associated Complex (MAC), a key immune signaling module, with both SIZ1 and the immune receptor SNC1 recruited to MAC-dependent nuclear condensates (MDNCs) upon pathogen challenge. These condensates serve as essential platforms for potentiating immune activation and cell death. Within the MDNC, SIZ1 promotes SUMOylation and stabilizes MAC components, thereby sustaining MDNC integrity during immune responses. Our findings reveal a previously unrecognized pro-immune role for SIZ1 and establish a mechanistic link between SUMOylation, MAC stability, and condensate-mediated immune signaling in plants.
Project description:Increased ambient temperature is widely considered to be inhibitory to basal and effector-triggered plant immunity. For example, SNC1-dependent auto-immunity in Arabidopsis results in enhanced basal resistance at 22ºC, which is fully suppressed at 28ºC. The sumoylation mutant siz1 also displays auto-immunity at 22ºC. We find that its auto-immunity is sustained at 28ºC while still requiring PAD4/EDS1 and SNC1 function. Moreover, its rosette size does not fully recover at 28ºC, which is normally seen for SNC1 gain-of-function mutants. Related, thermomorphogenesis is also compromised in the SUMO mutants. This role of SIZ1 in growth regulation does not depend on PAD4 or SNC1. In corroboration, SUMO mutants show a global delay in their transcriptional profile for thermosensitive growth regulators and these differentially expressed genes show an overrepresentation for PIF4 genomic targets. This transcription factor (TF) PIF4 is the central regulator of thermomorphogenesis, while also inhibiting plant immunity at 28ºC. Our findings thus reveal that SUMO conjugation has a central role in PIF4 regulation prioritizing growth over immunity at elevated temperatures. Such molecular understanding of how temperature affects growth over immunity is important to mitigate the effects of climate change on agriculture This experiment we have examined how gene expression is affected in two SUMO mutants (siz1-2; sumo1 amiR-SUMO1 [aka. sumo1/2KD] ) when the plants are placed at 28C constant ambient temperature, which is a condition normally used to induce thermomorphogenesis. We used as control the pad1-4 background, as the siz1-2 and sumo1/2KD mutants normailly suffer from constitutive defence signalling due hyperaccumulation of SA, which is suppressed by introgression of pad4 in these backgrounds.
Project description:Post-translational modifications of proteins by Small Ubiquitin-like Modifiers (SUMOs) regulate protein degradation and localization, protein-protein interaction, and transcriptional activity. SUMO E3 ligase functions are executed by SIZ1/SIZ2 in yeast and PIAS family members in human. The Arabidopsis genome contains only one gene, SIZ1, that is orthologous to yeast SIZ1/SIZ2. Here, we show that the Arabidopsis SIZ1 interacts with SUM1 and SCE1a, the SUMO E2 conjugating enzyme. Compared to WT, the null mutant siz-1-3 is smaller in statue because of reduced expression of gene involved in brassinosteroid biosynthesis and signalling. Drought stress induces the accumulation of SUMO-protein conjugates, which is in part dependent on SIZ1 but not on ABA. Mutant plants of siz1-3 have significant lower tolerance to drought stress. Genome wide expression analysis identified about 2,000 Arabidopsis genes that are responsive to drought, and SIZ1 mediates the induction of 600 of these genes by a pathway independent of DREB2A and ABA. SIZ1-dependent, drought-responsive genes include those encoding enzymes of the anthocyanin synthesis pathway and jasmonate response. From these results, we conclude that SIZ1 regulates Arabidopsis development and plays a role in drought stress response probably through the control of gene expression. Experiment Overall Design: 12 samples that includes 3 replicates of Col 0 under control conditions, 3 replicates of Col 0 expossed to 2 hr of dehydration, 3 replicates of siz1-3 under control conditions and 3 replicates of siz1-3 expossed to 2 hr of dehydration.
Project description:Post-translational modifications of proteins by Small Ubiquitin-like Modifiers (SUMOs) regulate protein degradation and localization, protein-protein interaction, and transcriptional activity. SUMO E3 ligase functions are executed by SIZ1/SIZ2 in yeast and PIAS family members in human. The Arabidopsis genome contains only one gene, SIZ1, that is orthologous to yeast SIZ1/SIZ2. Here, we show that the Arabidopsis SIZ1 interacts with SUM1 and SCE1a, the SUMO E2 conjugating enzyme. Compared to WT, the null mutant siz-1-3 is smaller in statue because of reduced expression of gene involved in brassinosteroid biosynthesis and signalling. Drought stress induces the accumulation of SUMO-protein conjugates, which is in part dependent on SIZ1 but not on ABA. Mutant plants of siz1-3 have significant lower tolerance to drought stress. Genome wide expression analysis identified about 2,000 Arabidopsis genes that are responsive to drought, and SIZ1 mediates the induction of 600 of these genes by a pathway independent of DREB2A and ABA. SIZ1-dependent, drought-responsive genes include those encoding enzymes of the anthocyanin synthesis pathway and jasmonate response. From these results, we conclude that SIZ1 regulates Arabidopsis development and plays a role in drought stress response probably through the control of gene expression. Keywords: stress response
Project description:The 5-methylcytosine DNA glycosylase/lyase REPRESSOR OF SILENCING 1 (ROS1)-mediated active DNA demethylation is critical for shaping the genomic DNA methylation landscape in Arabidopsis. Whether and how the stability of ROS1 may be regulated by post-translational modifications is unknown. Using a methylation-sensitive PCR (CHOP-PCR)-based forward genetic screen for Arabidopsis DNA hypermethylation mutants, we identified the SUMO E3 ligase SIZ1 as a critical regulator of active DNA demethylation. Dysfunction of SIZ1 leads to hyper-methylation at approximately one thousand genomic regions. SIZ1 physically interacts with ROS1 and mediates the SUMOylation of ROS1. The SUMOylation of ROS1 is reduced in siz1 mutant plants. Compared to that in wild type plants, the protein level of ROS1 is significantly decreased, even though there is an increased level of ROS1 transcripts in siz1 mutant plants. Our results suggest that SIZ1 positively regulates active DNA demethylation by promoting the stability of ROS1 protein through SUMOylation.
Project description:SUMOylation, a post-translational protein modification, is dramatically upregulated and critically involved in heat stress response conservatively among species. Previous studies in Arabidopsis indicated that numerous chromatin associated proteins are SUMOylation substrates and most of heat-enhancing SUMOylation reactions occur in nucleus. However, the global functional connection between gene expression regulation and SUMOylation on chromatin is completely unknown in plant cells. Here we show a genome-wide relationship of chromatin-associated SUMOylation and transcription switches under room temperature, heat stress, and recovering conditions in Arabidopsis. The SUMO-associated chromatin sites, characterized via whole-genome ChIP-seq assays, are generally correlated with active chromatin markers. In response to heat stress, we found chromatin-associated SUMO signals increased at promoter-transcriptional start site regions and decreased in the gene bodies. Further RNA-seq analysis supported the role of chromatin-associated SUMOylation in activation of transcription during rapid responses to high temperature. Changing of SUMO signals on chromatin is correlated with upregulation of heat-responsive genes and downregulation of growth-related genes. Disruption of the SUMO ligase gene SIZ1 abolishes SUMO signals on chromatin and attenuates the rapid transcriptional responses to heat stress. Interestingly, the SUMO signal peaks are enriched in DNA elements recognized by distinguished groups of transcription factors under different temperature conditions. Collectively, our data provide evidence that SUMOylation on chromatin regulates transcription switches during development and heat stress response, improving our understanding on the precise roles of SUMOylation in plant cells.
Project description:SUMOylation, a post-translational protein modification, is dramatically upregulated and critically involved in heat stress response conservatively among species. Previous studies in Arabidopsis indicated that numerous chromatin associated proteins are SUMOylation substrates and most of heat-enhancing SUMOylation reactions occur in nucleus. However, the global functional connection between gene expression regulation and SUMOylation on chromatin is completely unknown in plant cells. Here we show a genome-wide relationship of chromatin-associated SUMOylation and transcription switches under room temperature, heat stress, and recovering conditions in Arabidopsis. The SUMO-associated chromatin sites, characterized via whole-genome ChIP-seq assays, are generally correlated with active chromatin markers. In response to heat stress, we found chromatin-associated SUMO signals increased at promoter-transcriptional start site regions and decreased in the gene bodies. Further RNA-seq analysis supported the role of chromatin-associated SUMOylation in activation of transcription during rapid responses to high temperature. Changing of SUMO signals on chromatin is correlated with upregulation of heat-responsive genes and downregulation of growth-related genes. Disruption of the SUMO ligase gene SIZ1 abolishes SUMO signals on chromatin and attenuates the rapid transcriptional responses to heat stress. Interestingly, the SUMO signal peaks are enriched in DNA elements recognized by distinguished groups of transcription factors under different temperature conditions. Collectively, our data provide evidence that SUMOylation on chromatin regulates transcription switches during development and heat stress response, improving our understanding on the precise roles of SUMOylation in plant cells.
Project description:Short periods of heat (>37°C) are extremely damaging to non-acclimated plants and their capacity to acclimate to and recover from heat stress is a key parameter for their survival and longevity. To acclimate, the Heat Shock transcription Factor A1 (HSFA1) subfamily activates a transcriptional response that resolves the heat stress-induced protein damage. Importantly, HSFA1 activity is also critical for Arabidopsis to withstand sustained warmer periods of 28°C, a non-detrimental condition that triggers a thermomorphogenesis response. We find that SUMO, a protein modification whose adduct levels increase as a result of acute heat stress in eukaryotes, is also critical for plant longevity during warmer periods, in particular for shoot meristem development. The known E3 and E4 SUMO ligases (SIZ1, HPY1/MMS21, PIAL1/2) were not essential to endure these warmer periods, alone or in combination. Thermo-lethality was also not seen when plants lacked certain SUMO proteases (ESD4, OTS1/OTS2, SPF1/SPF2 combined) or when SUMO chain formation was blocked. Furthermore, SUMO thermo-resilience is not connected to the autoimmune phenotype found in the corresponding SUMO knockdown and a SIZ1 loss-of-function mutant. As acquired thermotolerance was normal in the SUMO knockdown mutant, we thus conclude that the role of SUMO in heat acclimation differs from that of HSFA1 and SIZ1. Combined, this study reveals that SUMO appears to be critical for shoot meristem integrity during warmer periods. This experiment we have examined how gene expression is affected in two SUMO mutants (siz1-2; sumo1 amiR-SUMO1 [aka. sumo1/2KD] ), and a HsfA1a,b,d triple mutant, when the plants are placed at 28C constant ambient temperature, which is a condition normally used to induce thermomorphogenesis. We used as control the pad1-4 background, as the siz1-2 and sumo1/2KD mutants normally suffer from constitutive defence signalling due hyperaccumulation of SA, which is suppressed by introgression of pad4 in these backgrounds.