Agricultural productivity is increasingly threatened by a range of abiotic stresses—including flooding, prolonged drought, and heat waves—as well as biotic stresses such as bacterial, fungal, and insect infections. These stressors contribute significantly to crop losses and pose a serious risk to global food security. Enhancing crop resilience under changing climatic conditions is therefore a critical priority.
This project, RedoxBoost, explores a novel strategy to improve stress tolerance in higher plants through the ectopic expression of selenoproteins, specifically selenocysteine-containing glutathione peroxidase (Sec-GPX) from the green alga Chlamydomonas reinhardtii (Sec-CrGPX). Selenoproteins incorporate selenocysteine (Sec), the 21st amino acid, which is uniquely encoded by the UGA stop codon and requires a specialized Sec insertion machinery composed of both cis- and trans-acting elements. While selenoproteins are found in certain eukaryotes (e.g. green algae, kinetoplastids) and some prokaryotes, they are absent in higher plants and fungi due to the lack of this machinery.
Sec-GPX is a prominent selenoprotein that catalyzes the reduction of hydrogen peroxide and lipid hydroperoxides, thereby mitigating oxidative damage. The central hypothesis of RedoxBoost is that introducing the Sec insertion machinery into Arabidopsis thaliana will enable the functional expression of Sec-CrGPX, thereby enhancing redox balance and stress resilience.
Objectives of RedoxBoost:
1. Identification, synthesis, and cloning of Sec-CrGPX and its associated cis- and trans-acting elements from Chlamydomonas reinhardtii, with codon optimization for expression in Arabidopsis.
2. Establishment of Sec incorporation in higher plants by integrating the Sec insertion machinery into Arabidopsis thaliana.
3. Functional characterization of transgenic Arabidopsis lines under various abiotic and biotic stress conditions.
This project aims to establish a previously unreported method for translating UGA into Sec in higher plants. Beyond expressing native selenoproteins, this mechanism could enable the incorporation of Sec into non-selenoproteins, potentially enhancing their biochemical properties. The outcomes of RedoxBoost may pave the way for broader applications of selenoproteins with oxidoreductase activity in plant biotechnology.
