title: Proteome readjustments in the apoplastic space of Arabidopsis thaliana ggt1 mutant leaves exposed to UV-B radiation.
abstract: Ultraviolet-B radiation acts as an environmental stimulus, but in high doses it has detrimental effects on plant metabolism. Plasma membranes represent a major target for Reactive Oxygen Species (ROS) generated by this harmful radiation. Oxidative reactions occurring in the apoplastic space are counteracted by antioxidative systems mainly involving ascorbate and, to some extent, glutathione. The occurrence of the latter and its exact role in the extracellular space are not well documented, however. In Arabidopsis thaliana, the gamma-glutamyl transferase isoform (GGT1) bound to the cell wall takes part in the so-called gamma-glutamyl cycle for extracellular glutathione degradation and recovery, and may be implicated in redox sensing and balance. In this work, oxidative conditions were imposed with Ultraviolet-B radiation (UV-B) and studied in redox altered ggt1 mutants. The response of ggt1 knockout Arabidopsis leaves to UV-B radiation was assessed by investigating changes in extracellular glutathione and ascorbate content and their redox state, and in apoplastic protein composition. Our results show that, on UV-B exposure, soluble antioxidants respond to the oxidative conditions in both genotypes. Rearrangements occur in their apoplastic protein composition, suggesting an involvement of Hydrogen Peroxide (H2O2), which may ultimately act as a signal. Other important changes relating to hormonal effects, cell wall remodeling, and redox activities are discussed. We argue that oxidative stress conditions imposed by UV-B and disruption of the gamma-glutamyl cycle result in similar stress-induced responses, to some degree at least. Data are available via ProteomeXchange with identifier PXD001807.
authors: Department of Agronomy, Food, Natural Resources, Animals and the Environment, University of Padova Padova, Italy.
authors: Anna Rita
authors: AR
authors: Trentin
authors: Department of Agronomy, Food, Natural Resources, Animals and the Environment, University of Padova Padova, Italy ; Proteomics Center of Padova University Padova, Italy.
authors: Micaela
authors: M
authors: Pivato
authors: Department of Agronomy, Food, Natural Resources, Animals and the Environment, University of Padova Padova, Italy.
authors: Syed M M
authors: SM
authors: Mehdi
authors: Sugarcane Breeding Institute Coimbatore, India.
authors: Leonard Ebinezer
authors: LE
authors: Barnabas
authors: Department of Agronomy, Food, Natural Resources, Animals and the Environment, University of Padova Padova, Italy.
authors: Sabrina
authors: S
authors: Giaretta
authors: Department of Agronomy, Food, Natural Resources, Animals and the Environment, University of Padova Padova, Italy.
authors: Marta
authors: M
authors: Fabrega-Prats
authors: Department of Agronomy, Food, Natural Resources, Animals and the Environment, University of Padova Padova, Italy ; Department of Bio-Engineering, Birla Institute of Technology Ranchi, India.
authors: Dinesh
authors: D
authors: Prasad
authors: Proteomics Center of Padova University Padova, Italy ; Department of Biomedical Sciences, University of Padova Padova, Italy.
authors: Giorgio
authors: G
authors: Arrigoni
authors: Department of Agronomy, Food, Natural Resources, Animals and the Environment, University of Padova Padova, Italy.
authors: Antonio
authors: A
authors: Masi
keywords: apoplast; gamma-glutamyl-transferase; glutathione; iTRAQ labeling; oxidative stress; ultraviolet-B radiation