An evolutionary view of the function of CC-type glutaredoxins in plant development and adaptation to the environment

Abstract

Land plants have to face an oxidizing, heterogeneous and fast changing environment. Redox-dependent post-translational modifications emerge as a critical component of plant responses to stresses. Among thiols oxidoreductases superfamily, class III CC-type glutaredoxins (called ROXYs) are land plant specific, and their evolutionary history is highly dynamic. Angiosperms encode many isoforms classified into five subgroups (Aα, Aβ, Bα, Bβ, Bγ) that probably evolved from five common ancestral ROXYs, with higher evolutionary dynamics in Bγ compared to other subgroups. ROXYs can modulate the transcriptional activity of TGAs transcription factors target genes, although their biochemical function is still debated. ROXYs participate in the control of proper plant development and reproduction, and are mainly negative regulators of plant responses to biotic and abiotic stresses. This suggests that most ROXYs could play essential and conserved functions in resetting redox-dependent changes in transcriptional activity upon stress signaling to ensure the responsiveness of the system and/or avoid exaggerated responses that could lead to major defects in plant growth and reproduction. Bγ members in Arabidopsis acquired important functions in responses to nitrogen availability and endogenous status, but the rapid and independent evolution of this subclass could suggest that this function results from neofunctionalization, specifically observed in core Eudicots.