Figure 9.

Proposed model for FBN2 function in photoprotection and JA-induced senescence inhibition. A, The PC-8 antioxidant synthesized by the enzyme VTE1 from PQ-9 is stored in PG. Then, the PC-8 and PQ-9 may transfer to the thylakoids for protection against ROS production under high-light conditions. It is necessary to expand PG and enzyme function to accumulate metabolites. Therefore, FBN2 may provide structural maintenance of PG for photoprotection. B, PG-localized proteins (PES1/2, PPH, and PGM48) have been associated with senescence, and JA biosynthesis enzymes (AOS and LOXs) have been frequently identified in PG studies. In JA-induced senescence, FBN2 may inhibit these proteins for metabolites accumulation such as phytyl esters and TAGs produced from chlorophyll degradation, as well as for JA initial biosynthesis as a PG structural protein. HL, high light.