The role of ferredoxin:thioredoxin reductase/thioredoxin m in seed germination and the connection between this system and copper ion toxicity

Seed germination is highly sensitive to changes in the surrounding environment. This work examined the impact of imbibition with copper solution on the germination rate and behavior of some enzyme capacities involved in stress response. Chickpea (Cicer arietinum L.) seeds were germinated at 25 °C in the dark for 7 days of imbibition with distilled water or an aqueous solution of chloride salt of 100 or 500 μM CuCl2. The exposure of seeds to copper (Cu2+) induced changes in the antioxidant status. In Cu-treated seeds, the non-protein thiols (SHNP) pool and ferredoxin:thioredoxin reductase (FTR) expression and activity increased. Cysteinyl sulfurs in the thioredoxin (Trx) function as ligands for metal ions. The accumulation of Cu2+ inhibited seed germination and embryo growth. It appears that the FTR system mediates a novel form of redox signaling in plants under copper excess.