Antagonistic cotranscriptional regulation through ARGONAUTE1 and the THO/TREX complex orchestrates transcriptional output.

Quantitative transcriptional control is essential for physiological and developmental processes in many organisms. Transcriptional output is influenced by cotranscriptional processes interconnected to chromatin regulation, but how the functions of different cotranscriptional regulators are integrated is poorly understood. The floral repressor locus () is cotranscriptionally repressed by alternative processing of the antisense transcript Proximal 3'-end processing of resolves a cotranscriptionally formed R-loop, and this process physically links to a histone-modifying complex FLD/SDG26/LD.

Natural temperature fluctuations promote regulation of .

Plants monitor many aspects of their fluctuating environments to help align their development with seasons. Molecular understanding of how noisy temperature cues are registered has emerged from dissection of vernalization in , which involves a multiphase cold-dependent silencing of the floral repressor locus (). Cold-induced transcriptional silencing precedes a low probability PRC2 epigenetic switching mechanism.

Antagonistic activities of cotranscriptional regulators within an early developmental window set expression level.

Quantitative variation in expression of the floral repressor influences whether plants overwinter before flowering, or have a rapid cycling habit enabling multiple generations a year. Genetic analysis has identified activators and repressors of expression but how they interact to set expression level is poorly understood. Here, we show that antagonistic functions of the activator FRIGIDA (FRI) and the repressor FCA, at a specific stage of embryo development, determine expression and flowering.

R-loop resolution promotes co-transcriptional chromatin silencing.

RNA-mediated chromatin silencing is central to genome regulation in many organisms. However, how nascent non-coding transcripts regulate chromatin is poorly understood. Here, through analysis of Arabidopsis FLC, we show that resolution of a nascent-transcript-induced R-loop promotes chromatin silencing.

HYPER RECOMBINATION1 of the THO/TREX complex plays a role in controlling transcription of the REVERSION-TO-ETHYLENE SENSITIVITY1 gene in Arabidopsis.

Arabidopsis REVERSION-TO-ETHYLENE SENSITIVITY1 (RTE1) represses ethylene hormone responses by promoting ethylene receptor ETHYLENE RESPONSE1 (ETR1) signaling, which negatively regulates ethylene responses. To investigate the regulation of RTE1, we performed a genetic screening for mutations that suppress ethylene insensitivity conferred by RTE1 overexpression in Arabidopsis. We isolated HYPER RECOMBINATION1 (HPR1), which is required for RTE1 overexpressor (RTE1ox) ethylene insensitivity at the seedling but not adult stage.