Sucrose-induced translational repression of plant bZIP-type transcription factors

Sugars as signalling molecules exert control on the transcription of many plant genes. Sugar signals also alter mRNA and protein stability. Increased sucrose concentrations specifically repress translation of the S-class basic region leucine zipper (bZIP) type transcription factor AtbZIP11/ATB2. This sucrose-induced repression of translation (SIRT) depends on translation of a highly conserved upstream open reading frame (uORF) in the 5′ UTR of the gene. This conserved uORF is exclusively encoded in 5′ UTRs of several plant S-class bZIP transcription factors. Arabidopsis homologues of ATB2/AtbZIP11, which harbour the conserved uORF, also show SIRT. Therefore, SIRT emerges as a general sucrose translational control mechanism of a group of transcription factors. SIRT might be part of a sucrose-specific signalling pathway, controlling expression of plant bZIP transcription factor genes.