The conundrum of discordant protein and mRNA expression. Are plants special?

Rapid progress in transcriptional and proteomic profiling methodologies, such as RNA-sequencing and high-resolution tandem mass spectrometry in combination with nanoflow chromatography, allows for a more accurate comparisons of disparate omics data sets at high resolution. Despite the increased fidelity of such surveys, several studies in mammals, yeast and plants have shown that transcript levels are not always a good proxy for protein abundance. While to some extent the modest concordance observed in studies across platforms may result from fundamentally different protocols that are used for the detection of proteins and mRNAs or caused by differences in the sensitivity of detection and data analysis (“false discordance”), it is becoming obvious that transcript/protein discordance is largely of biological origin (“true discordance”) and represents a critical layer of regulatory processes at the post-transcriptional level that is often neglected.