2. Dr. Shilo Rosenwasser

Environmental stresses are among the major factors that limit crop productivity and plant growth. Various non-destructive approaches for monitoring plant stress states have been developed. However, early sensing of the initial biochemical events during stress responses remains a significant challenge. In this work, we established whole-plant redox imaging using potato (Solanum tuberosum) plants expressing a chloroplast-targeted redox-sensitive green fluorescence protein 2 (roGFP2), which reports the glutathione redox potential (E_GSH). We mapped alterations in the chloroplast E_GSH under several stress conditions including high-light (HL), cold, and drought. An extremely high increase in chloroplast E_GSH was observed under the combination of HL and low temperatures, which specifically induce PSI photoinhibition. In addition, redox imaging was applied to detect the early signs of oomycete Phytophthora Infestans infection, causing late blight, a devastating potato disease that led to the Irish potato famine. Using spatially resolved patterns of roGFP2 oxidation state from infected plants, we demonstrated the capability to detect the early presymptomatic biotrophic stage of the diseases, prior to the appearance of irregular-shaped spots, the typical visual symptoms. The presented observations suggest that whole-plant redox imaging can serve as a powerful tool for the basic understanding of plant stress responses and applied agricultural research, such as improving phenotyping capabilities in breeding programs and early detection of stress responses in the field.