Figure 3.

Mitophagy is not induced by various general stresses. IDH1-GFP, GFP-TOM20-3, GFP-ATG8e fusion proteins, and free GFP were detected by immunoblotting using an anti-GFP antibody, after UV-B stress (A), hydrogen peroxide (H₂O₂) treatment (B), heat stress recovery (C) or hypoxia (D). For each representative blot, Ponceau S-stained RBCL from total protein lysates was included as loading control (PonS, bottom panels). (A-B) 10-d-old seedlings grown on 1/2 MS medium with 1% sucrose were exposed to 10,000 mJ cm⁻² UV-B (A) or sprayed with 100 mM H₂O₂ (B) and returned to standard growth conditions. Plant photographs at the top panels, show representative seedlings 8–48 h after the stress treatments. Scale bars: 7 mm. (C) Top panel indicates schematic representation of temperature regimes applied to study heat stress (HS). 7-d-old seedlings were exposed to mild HS at 37°C, returned to optimal temperature at 22°C for recovery followed by high HS at 44°C. Seedlings were additionally returned to standard growth conditions for 1–3 days for the prolonged HS recovery phase. (D) Top panel shows schematic representation of the multi-well plate experimental set up, applied to probe hypoxia stress. Whole leaves of 5-week-old plants were gently immersed in 24-well plates filled with assay medium, vacuum-treated in a desiccator for 3 min to remove residual air from intracellular tissue spaces, and sealed with transparent film to block O₂. Control samples were treated the same, except plates were left unsealed throughout 24 h of incubation. Relative intensity ratios (% of free GFP:GFP-mito or GFP-ATG8e) for all abiotic stresses are shown as numeric values below blots.