The Relationship Between Plant Cyanide-Resistant Respiration And Expression Of Alternative Oxidase

In this paper, the relationship between cyanide-resistant respiration and expression of alternative oxidase (AOX) using polyantibodies prepared by synthetic polypeptide in mung bean seedling, as well as the effects of vernalization on cyanide-resistant respiration and expression of AOX in winter wheat were studied respectively.In the first part, twelve peptides, including eight conservative amino acid residues in the amino acid sequence of hydrophilic S helix of AOX. were synthesized by solid-phase method. The polypeptide was coupled to a -chymotrypsinogen, and the antibodies were obtained through immunizing rabbit by injecting this complex. By using these antibodies, which were raised to immunoreact with total proteins of purified mitochondria from different organs of mung bean seedlings, we find that there were two hybridizable AOX bands in mitochondria in mung bean seedlings. Their molecular weight was about 35kD and 38kD respectively. Moreover, the respiratory parameters of hypocotyl, true leaf and cotyledon of mung bean seedlings showed that true leaf had the highest total respiration (Vt), alternative pathway (AP) capacity (Valt) and the activity of AP ( P Valt) among the three organs. The second werecotyledon Vt and P Valt. Hypocotyl Vt and P Valt were the lowest, but its Valt was higher than that of cotyledon. These results were consistent with the analysis of Western blotting of expression of AOX. The highest Vt and P Valt in true leaf were accompanied two hybridizable polypeptides of AOX protein, 35kD and 38kD respectively. The next was cotyledon Vt and P Valt with only one 38kD hybridizable polypeptide of AOX protein. Hypocotyl Vt and P Valt were the lowest and its immunobloting band was similar to that of cotyledon, but the expressive amount of 38kD protein was less than that of cotyledon. The experiments indicated that the 35ku AOX may make the main contribution to true leaf P Valt.In the second part, the winter wheat embroy under vernalization treatment was used to study the effects of non-stress-vernalization low temperature treatment on the development and operation of cyanide-resistant respiration and expression of AOX. The Valt and the P Valt of cyanide-resistant respiration were induced dramatically as well as the total respiration in early stage of vernalization treatment and deceased subsequently. The Western blotting results also showed the parallel changes. During the whole treament time of 0-30d, although the cyanide-resistant respiration was increased, its opearation was lower than the cytochrome pathway which also made the main contribution to total respiration of winter wheat. We concluded that the increasement of cyanide-resistant respiration in the early stage of vernalization might be related to the adaptation of low temperature when winter wheat lives through the winter.