A New Conditional Gene Regulation System in Plants

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The ability to switch gene expression on and off is a critical factor in an organism's capacity to respond to internal and external cues. The sessile nature of plants means that the need to be able to respond rapidly to ever changing environmental conditions is of particular importance. Until recently, it was thought that the major pathways of gene regulation occurred before transcription. However, it is now known that post-transcriptional processes play a crucial role in regulating gene expression. Among these processes is the control of mRNA stability. Whereas the regulation of mRNA stability by miRNAs has been well explored in plants and continues to provide new insights into plant growth and development, other forms of mRNA stability control are less well understood. Some mRNA transcripts are specifically targeted for degradation based on inherent features that induce a process known as nonsense-mediated mRNA decay (NMD). NMD regulates the stability of a large number of eukaryotic transcripts (of the order of 10% in a range of species), and by moving transcripts into or out of the influence of NMD a cell is able to respond quickly to urgent signals. We have recently discovered that a highly conserved signal (the Conserved Peptide upstream Open Reading Frame - CPuORF) targets specific mRNAs for destruction by NMD. Our evidence suggests that this happens conditionally, in response to a range of signals including abiotic stress, the presence of specific small molecules and in response to changes in translational efficiency. Together with Bayer CropScience, as part of an Industrial partnership Award, we seek support to investigate this novel form of posttranscriptional regulation of gene expression and to determine its potential for crop improvement.