Project description:The genome-wide target genes of transcription factors MYC2 and MYC3 were determined in etiolated (dark-grown) seedlings of Arabidopsis thaliana. Chromatin immunoprecipition of MYC2 and MYC3 was performed as described in O’Malley et al (2016; doi: 10.1016/j.cell.2016.04.038), using transgenic A. thaliana expressing MYC2::YpET and MYC3::YpET fusion proteins from their native promoters, generated by recombineering (Gimenez-Ibanez et al. 2017; doi: 10.1111/nph.14354 ). Three-day old etiolated seedlings were treated with methyl JA for 2 h (as described in Schweizer et al., 2013), then harvested for ChIP-Seq.
Project description:Plants are continuously exposed to environmental triggers, including mechanical stimulation. Our results demonstrate that jasmonic acid (JA)-signalling plays a key role in very early gene expression changes, well before it leads to touch-induced developmental changes. We show that the JA-activated transcription factors MYC2/MYC3/MYC4 co-regulate touch-induced gene expression of 266 genes, many of which peak in induction around 25 minutes and then rapidly decline by 40-60 minutes. ChIP-seq shows that MYC2 dynamically binds hundreds of touch-induced promoters within 25 minutes. Promoter activation assays confirm that MYC2 directly activates these touch-induced promoters. By combining multi-omic data, we have identified a core MYC2/3/4-dependent ‘touch regulon’, containing many previously-unknown MYC2 targets like bHLH19 and ERF109. We show bHLH19 can in turn directly activate the ORA47 promoter, indicating that MYC2/3/4 initiate a hierarchical network of downstream transcription factors. Through hormone profiling we reveal the rapid touch-induced accumulation of JA/JA-isoleucine is directly controlled by MYC2/3/4 in a positive amplification loop regulating JA-biosynthesis genes.
Project description:Plants are continuously exposed to environmental triggers, including mechanical stimulation. Our results demonstrate that jasmonic acid (JA)-signalling not only plays a key role in touch-induced developmental changes, but also in the very early gene expression changes. Using multi-omics, we show that the JA-activated transcription factors MYC2/MYC3/MYC4 co-regulate touch-induced gene expression of 266 genes. MYC2/3/4 particularly activate top touch-induced genes, which peak around 25 minutes and then rapidly decline by 40-60 minutes. ChIP-seq shows that MYC2 dynamically binds hundreds of touch-induced promoters within 25 minutes. Furthermore, promoter activation assays confirm that MYC2 directly activates touch-induced promoters. By combining these data, we identified a core MYC2/3/4-dependent ‘touch regulon’, containing many previously-unknown MYC2 targets like bHLH19 and ERF109. bHLH19 can in turn directly activate the ORA47 promoter, indicating that MYC2/3/4 initiate a hierarchical network of downstream transcription factors. Finally, hormone profiling shows that the rapid touch-induced accumulation of JA/JA-isoleucine is directly controlled by MYC2/3/4 in a positive amplification loop regulating JA-biosynthesis genes.
Project description:Jasmonate (JA) is a plant hormone that controls trade-offs between plant growth and responses to biotic and abiotic stresses. Although recent studies uncover core mechanism for JA-induced responses in Arabidopsis thaliana, it remains elusive how plants attenuate those responses. We report here that a basic-helix-loop-helix type transcription factor named JA-INDUCIBLE MYC2-LIKE1 (JAM1) acts as a transcriptional repressor and negatively regulates JA signaling. Arabidopsis plants expressing the chimeric repressor for JAM1 exhibited a substantial reduction of JA responses, including JA-induced inhibition of root growth, accumulation of anthocyanin, and male fertility. These plants were also compromised in resistance to attack by Spodoptera exigua. Conversely, jam1-4 loss-of-function mutants showed enhanced JA responsiveness, including increased resistance to the insect attack. Competitive binding of JAM1 and MYC2 to the target sequence of MYC2 suggested negative regulation of JA signaling by JAM1 and suppression of MYC2 function. These results indicate that JAM1 plays a pivotal role in fine-tuning of JA-mediated stress responses and plant growth by negatively regulating JA signaling. Transcriptomes of ProJAM1:JAM1-SRDX, ProMYC2:MYC2-SRDX and wild-type Arabidopsis seedlings with or without jasmonic acid were compared.
Project description:Jasmonate (JA) is a plant hormone that controls trade-offs between plant growth and responses to biotic and abiotic stresses. Although recent studies uncover core mechanism for JA-induced responses in Arabidopsis thaliana, it remains elusive how plants attenuate those responses. We report here that a basic-helix-loop-helix type transcription factor named JA-INDUCIBLE MYC2-LIKE1 (JAM1) acts as a transcriptional repressor and negatively regulates JA signaling. Arabidopsis plants expressing the chimeric repressor for JAM1 exhibited a substantial reduction of JA responses, including JA-induced inhibition of root growth, accumulation of anthocyanin, and male fertility. These plants were also compromised in resistance to attack by Spodoptera exigua. Conversely, jam1-4 loss-of-function mutants showed enhanced JA responsiveness, including increased resistance to the insect attack. Competitive binding of JAM1 and MYC2 to the target sequence of MYC2 suggested negative regulation of JA signaling by JAM1 and suppression of MYC2 function. These results indicate that JAM1 plays a pivotal role in fine-tuning of JA-mediated stress responses and plant growth by negatively regulating JA signaling.
Project description:Analyses of the regulatory repertoire showed that distal active cis-regulatory elements (CREs) are linked to their target genes through long-range chromatin interactions with increased expression, and poised CREs are linked to their target genes through long-range chromatin interactions with depressed expression. Furthermore, we demonstrated that transcription factor MYC2 is critical for chromatin spatial organization, and proposed that MYC2 occupancy and MYC2-mediated chromatin interactions coordinately facilitate transcription within the framework of 3D chromatin architecture. An analysis of functionally related gene-defined chromatin connectivity networks revealed that genes implicated in flowering-time control are functionally compartmentalized into separate subdomains via their spatial activity in the leaf or shoot apical meristem, linking active mark- or H3K27me3-associated chromatin conformation to coordinated gene expression. The results showed that the guiding principle for modulating gene transcription in Arabidopsis includes not only the linear juxtaposition, but also the long-range chromatin interactions.
Project description:The hormone jasmonic acid (JA) controls a plethora of crucially important processes in plants through a signaling pathway orchestrated by the transcription factor MYC2 and its closest relatives. Understanding the systems-level actions of transcription factors provides insight into how the genome is reprogrammed in response to environmental stimuli. However, deeper biological insight can be obtained if transcription factor activity is set in the broader regulatory context of the cell and the downstream organismal phenotypes the transcription factors control. Here, we have investigated the MYC2-governed genome regulatory network that controls JA responses in Arabidopsis thaliana etiolated seedlings. We have generated an integrated framework of the response to JA that spans from the activity of master and secondary-regulatory transcription factors, through gene expression outputs and alternative splicing to protein abundance changes, protein phosphorylation and chromatin remodeling. We have integrated time series transcriptome analysis with (phospho)proteomic data using gene regulatory network models. These enable us to predict previously unknown points of crosstalk from JA to other signaling pathways and to identify new components of the JA regulatory mechanism, which we validated through targeted mutant studies. The result is a comprehensive understanding of how a plant hormone remodels cellular function and plant behavior, the general principles of which provide a framework for analysis of cross-regulation between other hormone and stress signaling pathways.
Project description:Comparison of mock-treated vs. methyl jasmonate-treated (6 hours, 0.1 uM) wild type (Col-0) vs. myc2 (jin1-9) mutant Arabidopsis lines. Note: an error in the processing of the normalized data was noticed November 2008. Corrected data was reloaded 1st December 2008.
Project description:Analyses of the regulatory repertoire showed that distal active cis-regulatory elements (CREs) are linked to their target genes through long-range chromatin interactions with increased expression, and poised CREs are linked to their target genes through long-range chromatin interactions with depressed expression. Furthermore, we demonstrated that transcription factor MYC2 is critical for chromatin spatial organization, and proposed that MYC2 occupancy and MYC2-mediated chromatin interactions coordinately facilitate transcription within the framework of 3D chromatin architecture. An analysis of functionally related gene-defined chromatin connectivity networks revealed that genes implicated in flowering-time control are functionally compartmentalized into separate subdomains via their spatial activity in the leaf or shoot apical meristem, linking active mark- or H3K27me3-associated chromatin conformation to coordinated gene expression. The results showed that the guiding principle for modulating gene transcription in Arabidopsis includes not only the linear juxtaposition, but also the long-range chromatin interactions.
Project description:Analyses of the regulatory repertoire showed that distal active cis-regulatory elements (CREs) are linked to their target genes through long-range chromatin interactions with increased expression, and poised CREs are linked to their target genes through long-range chromatin interactions with depressed expression. Furthermore, we demonstrated that transcription factor MYC2 is critical for chromatin spatial organization, and proposed that MYC2 occupancy and MYC2-mediated chromatin interactions coordinately facilitate transcription within the framework of 3D chromatin architecture. An analysis of functionally related gene-defined chromatin connectivity networks revealed that genes implicated in flowering-time control are functionally compartmentalized into separate subdomains via their spatial activity in the leaf or shoot apical meristem, linking active mark- or H3K27me3-associated chromatin conformation to coordinated gene expression. The results showed that the guiding principle for modulating gene transcription in Arabidopsis includes not only the linear juxtaposition, but also the long-range chromatin interactions.