A Comparative Study on Induction of the CN-resistant Respiration and the Expression of Alternative Oxidasein Different Organs of Bean Seedling Treated by Salicylic Acid

Effects of salicylic acid (SA) treatment on alternative pathway capacity (V_(alt)) and its actual operation activity (ρV_(alt))and the expression of alternative oxidase (AOX)in different organs of bean(Phaseolus vulgaris cv.)seedlings were studied. The results demonstrate that the cyanide-resistant respiration exists in different organs of bean seedlings, and the ρV_(alt) in true leaf was the highest, that in cotyledon the next, and hypocotyl ρV_(alt) was the lowest. Both of the V_(alt) and ρV_(alt) among the three organs dramatically increased after SA treatment for 24h. However, the order of their ρV_(alt) was consistent. It is evident that the respiratory specificity of the different organs did not changed with the induction of cyanide-resistant respiration by SA treatment in bean seedlings. Western blotting analysis shows that the difference of V_(alt) and ρV_(alt) among the organs of bean seedlings was correlative with the changes in the level of AOX protein. Therefore, the amount of expressed AOX protein true leafcotyledonhypocotyl among the three organs. In the bean seedlings treated with SA, the enhancement in the cyanide-resistant respiration among the different organs coincides with the increase in synthesis of AOX.