PLANT CIRES BIOTECH · Functional characterization of plant cellular IRES in response to abiotic stress and their use as biotechnological tools

To cope with abiotic stresses plants require an extensive molecular regulation of gene expression. In plants, translation is a key step in the control of gene expression under abiotic stress conditions. This translational regulation involves (1) a global inhibition of protein synthesis and (2) an efficient and selective translation of certain mRNAs, generally codifying proteins involved in the abiotic stress response. Although in plants the mechanisms involved in the onset of this dual regulation are currently unknown, some evidences point out that cap independent translation, via recognition of internal ribosome entry sites (IRES) within the mRNAs efficiently translated, could be the clue for the selective protein synthesis observed under such conditions.In this proposal we aim to further characterize the cellular IRESs operating under abiotic stress conditions in plants and to exploit the identified cellular IRESs as biotechnological tools to allow the efficient and selective translation of mRNAs of interest under abiotic stress conditions. In plants, no IRES trans-acting factors (ITAFs) and only two cellular IRESs have been identified so far. Therefore, the systematic identification of new cellular IRESs, the identification for the first time of ITAFs and the study of how they can control IRES activity-specificity under abiotic stress conditions are important steps forward in the knowledge of how plants adapt to environmental stresses. In addition, the pioneering use of the identified cellular IRESs as a tool to tightly and specifically control the expression of proteins of interest under abiotic stress conditions will open up a new perspective for the study of abiotic stress in plants and for the generation of plants with increased tolerance to such conditions.