Increased sucrose levels mediate selective mRNA translation in Arabidopsis

Background Protein synthesis is a highly energy demanding process and is regulated according to energy availability in plant cells. Light and sugar availability affect mRNA translation but the specific roles of these factors remain unclear. In this study, sucrose was applied to Arabidopsis seedlings kept in the light or in the dark, in order to distinguish sucrose and light effects on transcription and translation. These were studied using microarray analysis of steady state mRNA and mRNA bound to translating ribosomes. Results Steady state mRNA levels were affected differently by sucrose in the light and in the dark but general translation increased to a similar extend in both conditions. Alterations in polysomal mRNA association closely followed the changes induced on the transcript level. However, for 243 mRNAs, a change in ribosome occupancy was observed after sucrose treatment in the light, but not in the dark condition. Many of these mRNAs are annotated as encoding ribosomal proteins, supporting specific translational regulation of this group of transcripts. Unexpectedly, the numbers of ribosomes bound to each mRNA decreased for mRNAs with increased ribosome occupancy. Conclusions Our results suggest that sucrose regulate translation of these 243 mRNAs but specifically in the light, through a novel regulatory mechanism. Our data sows that increased polysomal association is not necessarily leading to more ribosomes per transcript, suggesting a mechanism of translational induction not solely dependent on increased translation initiation rates. Four different samples groups were used: Control, Darkness, Sucrose, Simultaneous Darkness and sucrose treatments. All sample groups was represented by both total mRNA hybridization and of mRNAs from polysomal enrichment. All sample groups were represented by three biological replicates.