Target of rapamycin (TOR) regulates CURLY LEAF (CLF) translation in response to environmental stimuli

The target of rapamycin (TOR)-Polycomb repressive complex 2 (PRC2) pathway is a crucial link that translates environmental and developmental cues into chromatin, thus reprogramming transcription. While the PRC2 methyltransferase Curly leaf (CLF) is known to be specifically involved, the underlying mechanism remains unclear. This study sheds light on how TOR fine-tunes CLF protein levels by promoting translation re-initiation mediated by eIF3h. We found that the second upstream open reading frame (uORF) located in the 5' leader region of the CLF transcript significantly represses its translation (by 50%). Plants lacking this uORF leader displayed reduced sensitivity to TOR inhibition and impaired induction of stress-responsive genes. Interestingly, this uORF sequence exhibits partial conservation across diverse plant species, suggesting a potential role in adaptation to various environmental conditions. Our findings reveal a dynamic mechanism within the TOR-PRC2 pathway, highlighting its responsiveness to environmental stimuli.