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

Final Report Summary - PLANT CIRES BIOTECH (Functional characterization of plant cellular IRES in response to abiotic stress and their use as biotechnological tools)

Plants, as sessile organisms, are constantly exposed to a wide spectrum of stress conditions and are forced to adapt to them in order to complete their life cycle. These environmental stresses, such as heat, drought, high salinity or pathogen attack, severely reduce crop yield and quality causing important losses in agricultural production. In this sense, one of the main challenges of Agriculture is to improve food production by increasing crop tolerance to adverse conditions, a goal that can only be achieved from a deep knowledge of the molecular mechanisms that allow plants to survive and adapt to these environmental stresses.

Translation has recently emerged as a pivotal process for gene expression regulation in response to different stresses. However, the mRNAs that are selectively translated under such conditions and the mechanims that modulate their selective translation are highly unknown in plants. In order to get a deeper insight on how plants respond and adapt to the environmental challenges from the translational point of view, we have monitored the changes in the translation efficiency of individual mRNAs of Arabidopsis thaliana upon a exposure to heat stress. This analysis demonstrates that plants subjected to high temperatures undergo a general translational blockage that affects to the majority of the mRNAs. In addition, this study also uncovers the differential translation of specific mRNAs related to protein synthesis and stress response. This research also promoted to the identification and characterization of a new plant-specific translational regulator that tackles differential translation of specific sets of mRNAs during plant development.

In order to get a deeper insight in the plant response to heat stress, we have also carried out a high-throughput comparative proteomics analysis during acclimation to high temperatures and during the early stages of the plant response to a severe heat stress that lead Arabidopsis seedlings either to survival or death. This analysis has allowed us to dissect the different responses to heat, to reveal the common players and to identify the specific proteins associated with plant death or plant survival under high temperature. Moreover, this study has uncovered new proteins that play a key role in the plant adaptation to heat stress. One of these proteins that was identified as a potential new regulator of the heat tress response is AtHOP3. The characterization of this protein and other members of its family in Arabidopsis has demonstrated that HOPs play a fundamental role in endoplasmic reticulum (ER) stress and in long term acquired thermotolerance in plants. Our data also demonstrate that HOPs are a central hubs in the plant adaptation to other multiple stresses.

All the data generated during this study have considerably increased our knowledge on how plants respond and adapt to different environmental stresses and have opened new avenues to generate biotechnologicals tools to enhance crop tolerance to environmental challenges.