A model showing GFP export from chloroplasts of transplastomic plants under stress.
Erwinia carotovora and paraquat generate superoxide anions and H2O2. These reactive oxygen species (ROS) oxidize chloroplast lipid membranes and alter chloroplast envelope, increasing ion leakage. Consequently stromal proteins are exported from the chloroplasts into the cytoplasm. The signal molecules include H2O2, PTM (a chloroplast envelope-bound plant homeodomain transcription factor under photo-oxidative stress), PAP (3′-phosphoadenosine 5′-phosphate under high light or drought stress) are present in the chloroplast under stress conditions and communicate with nucleus to regulate stress responsive and antioxidant genes. ABI, abscisic acid insensitive transcription factors; DREB, dehydration responsive element binding proteins; ZAT, zinc finger transcription factors; APX, ascorbate peroxidase genes; PR, pathogenesis related genes; SA, salicylic acid; JA, jasmonic acid; and ET, ethylene. Early events caused by biotic/abiotc stress treatments in this study are represented in black solid and dotted arrows. Downstream signaling events following the outburst of ROS, which have been reported in previous studies by other groups, are indicated in red solid and dotted arrows, and letters. Yellow dots represent cell wall degrading enzyme secreted by Erwinia.