Comparison of the Effects of H2O2 and Salicylic Acid on Alternative Respiratory Pathway in Aged Potato Tuber Slices

The influences of exogenous H 2O 2 and salicylic acid (SA) treatments on the alternative respiratory pathway (ARP) in aged potato (Solanum tuberosum L.) tuber slices were compared. The results showed that both H 2O 2(5.0 mmol/L) and SA (0.1 mmol/L) treatments had a significant inducing effect on ARP capacity (V alt ) and its ratio to total respiration (V alt /V t) in potato slices aged for 24 h. With a monoclonal antibody against the alternative oxidase (AOX), Western blotting results showed that both H 2O 2 and SA treatments increased the AOX expression levels in aged potato tuber slices. However, the results of oxygen isotope discrimination experiments showed that H 2O 2 had no influence on the in vivo ARP activity (ρV alt ) and its contribution to V t(expressed as ρV alt /V t) in potato slices aged for 24 h, but SA had a significant influence on the ρV alt and ρV alt /V t values of the aged potato tuber slices. These results indicate that there are differences between the effects of H 2O 2 and SA on ARP in plant tissues. Both of them possess the ability to induce ARP capacity through inducing AOX expression. However, SA can simultaneously stimulate the operation of ARP, but H 2O 2 can not.