Updated project metadata. Retrograde signals emanate from the DNA-containing cell organelles (plastids and mitochondria) and control the expression of a large number of nuclear genes in response to environmental and developmental cues. Previous studies on retrograde signaling mainly analyzed the regulation of nuclear gene expression at the transcriptional level. To determine the contribution of post-transcriptional regulation to plastid retrograde signaling, we combined label-free proteomics with transcriptomic analysis of Arabidopsis thaliana seedlings and studied the response in whichto interference with the plastid gene expression (PGE) pathway of retrograde signaling.