Figure 6.

Model for Fd I functions during viral infections. After it is synthesized in the cytoplasm, the Fd I precursor is imported into chloroplasts because of the transit peptide (TP), which is removed inside the chloroplasts. Our data indicate that the CP of CMV interacts with the Fd I precursor to inhibit the import process. Decreases in Fd I production following an infection by CMV will need to be further verified. Because Fd I localizes on the stromal side of chloroplasts and transfers electrons from photosystem I (PS I) to various pathways, decreases in Fd I abundance will disrupt the electrons transport chain and influence Fd I-dependent metabolic activities. This will ultimately lead to an increase in H₂O₂ levels and inhibited chloroplast function.