Proteomics link translational reprogramming to S-glutathionalytion and induced priming during cold acclimation in barley roots

Plants due to their sessile nature rely on root systems to mediate many challenging stimuli. A major cornerstone of the responses are root proteomes, shaped to overcome biotic and abiotic cues. Proteome-wide reprogramming events are magnified in root meristems due to their active protein production. Using root meristems as a test system, we here study the major rewiring that plants face during cold acclimation. To achieve that, we performed tandem mass tag (TMT) label-mediated bottom-up proteomics of two consecutive segments of barley root apexes, comparing changes in global protein contents and individual protein abundances. We report an intricate translational reprogramming happening in the distal apex zone. The reprogramming includes all the translational machinery from ribosome biogenesis to protein folding, even suggesting roles for cold-specific ribosomal protein (RP) paralogs. Finally, this event is accompanied by upregulation of glutathione production and S-glutathionylation assemblage machineries. To summarize, we couple previous reports of an alternatively cold-spliced transcriptome to potential cold-specialized ribosomes and subsequent posttranslational modification (PTM), S-glutathione, of proteins. We propose that these PTMs protect the proteome during cold by acting as ROS scavengers, and consequently, provide a mechanistic link to the cold priming capabilities for root-specific biotic stress.