An operational Asada-Halliwell cycle is established in tuber by measuring all the component enzymes namely, APx (ascorbate peroxidase), GR (glutathione reductase), DHAR (dehydroascorbate reductase), MDHAR (mono-dehydroascorbate reductase) and end products, ascorbate (AsA) and glutathione (GSH) of the cycle.

The associated CA (carbonic anhydrase), DHAR (Dehydroascorbate reductase), MDHAR (monodendroascorbate reductase), activities were higher during germination suggesting the probable role of these enzymes in germination and may serve as markers of tuber growth.

The nitric oxide (NO,) and S-nitrosothiol (SNO,) content were higher during maturation supporting overall oxidative conditions. The S-nitrosylation of dioscorin is reported for the first time.

GSNO & CysNO, NO donors negatively regulated the CA, DHAR, MDHAR, APx and GR activities indicating the involvement of NO in this inhibition.