Nutrient-driven TOR signaling mediates transcriptional repression by promoting translation to regulate plant growth [ChIP-seq]
As is well known, nutrition is essential for plant growth and development. Extensive research has demonstrated that the target of rapamycin (TOR) is a crucial growth regulator, receiving nutritional inputs in eukaryotic cells. Nevertheless, the precise mechanisms by which TOR coordinates nutrient conditions and growth remain elusive in plants. In this study, we identified a novel transcriptional repression complex, TRCG, downstream of the TOR signaling pathway. This complex is responsible for regulating plant growth and the nutritional response. In the presence of favorable nutritional conditions, TOR is activated, leading to the translation of the 5'-terminal oligopyrimidine (5'-TOP) mRNA of TRCG. TRCG directly binds numerous nutrition-responsive genes, particularly those belonging to the ERF family of transcription factors, to repress their transcription. This repression is achieved by influencing the initiation and elongation of RNA polymerase II (Pol II), thereby maintaining growth and development. In the absence of nutritional conditions, TOR activity is inhibited, resulting in the repression of TRCG translation. This, in turn, relieves the repression of nutrient response genes, causing a stagnation of growth and poor nutrient resistance, thus contributing to the survival of the plant. Moreover, we observed a higher histone H3 and H4K5 acetylation level in the TRCG targets. Acetylated chromatin has long been associated with transcriptional activation, suggesting that TRCG could bind to acetylated chromatin to repress transcriptional activation. Our findings elucidate a previously unidentified precise mechanism by which TOR-mediated transcriptional repression occurs through the stimulation of translation, thereby regulating plant growth and the nutritional response. Overall design: Examination of protein binding levels in transgenic plants; For Pol II 2p and 5p ChIP-seq, examination of Pol II 2p and 5p levels in wild type, drmy1, gtb123.