Functions of violaxanthin de­epoxidase-related (VDR) in the photoprotective response to high-light stress

Abstract

Abstract The xanthophyll cycle is crucial for protecting plants and algae from photodamage. While the resistance of the violaxanthin de-epoxidase enzyme (VDE) to high-light stress in the xanthophyll cycle has been extensively studied, there is limited knowledge about VDE-related (VDR) proteins, which share a close homologous relationship with VDEs. In this study, we conducted a preliminary investigation of VDR protein from the aspects of basic bioinformatics, spatiotemporal gene expression patterns, and strong light stress treatment. Through subcellular localization experiments, we observed that the CsVDR-GFP protein was predominantly located in chloroplasts. CsVDR was expressed in all tissues of Arabidopsis and cucumber, with the highest expression level observed in mature leaves cultivated for 20 days in cucumber. Interestingly, both CsVDR and AtVDR were identified as high-light response genes. However, when subjected to high-light stress, all CRISPR/Cas9 mediated gene-edited Arabidopsis mutants (Atvdr) exhibited a decreasing trend in the de-epoxidation ratio of (A+Z)/(A+Z+V) and non-photochemical quenching (NPQ) compared to the wild-type (WT) lines. This suggests that the xanthophyll cycle in Atvdr was less effective and more susceptible to photoinhibition of PSII under high-light stress. Our findings provide evidence that VDR proteins play a role in regulating the high-light response in plants, thereby offering a theoretical basis for further investigation into plant photoprotective pathways.