Effects of Exogenous Nitric Oxide on Krebs Cycle-associated Enzyme Activities in Feicheng Peach Fruit

摘要

This study was aimed at assessing the effects of long-term exposure to nitric oxide (NO) on Krebs cycle in mitochondria of postharvest 'Feicheng' peaches. Changes in the activities of pyruvate dehydrogenase complex (PDHC) and all enzymes of the Krebs cycle in peach fruits treated with NO (0, 5, 15, and 30 ul L-1 of NO at 4 °C for up to 30 days) were measured. The results showed that NO made a dramatic promotion of activities of PDHC, a-ketoglutarate dehydrogenase complex (aKGDHC), fumarase (FUM) and malate dehydrogenase (MDH), whereas a inhibition of those of succinate thiokinase (STK) and succinate dehydrogenase (SDH). Activities of aconitase (ACN), isocitrate dehydrogenase (IDH) were promoted or prevented dependent on the concentration of NO and treatment time. It was also found that succinic acid in peach fruits treated with 30 and 5 ul L1 NO has a dramatic accumulation on day 18 and day 24, respectively. These results suggested that NO treatment significantly affected Krebs cycle in postharvest peaches: NO inhibited the Krebs cycle of postharvest fruits via inhibiting the activities of STK and SDH. In addition, the inhibition of SDH by NO was further significant compared with STK, which led to the accumulation of succinic acid.