Isolation of an ascorbate peroxidase in <em>Brassica napus</em> and analysis of its specific interaction with ATP6

Abstract

In Brassica napus, ATP6 is related to Pol cytoplasmic male sterility. To understand the mechanism of Pol CMS, proteins which interact with ATP6 were screened in a yeast two-hybrid system. A partial sequence of a putative and ascorbate peroxidase (Bn-APX) was isolated from Brassica napus. By use of rapid amplification of cDNA ends method, the full length of Bn-APX coding sequence was cloned. The deduced amino acid sequence contained 438 amino acid residues with a conserved ascorbate peroxidase domain and shared 77% identity with that of APX from Arabidopsis thaliana. Further analyses revealed that the region of Bn-APX interacting with ATP6 was at its c-terminal. It was also observed that the expressions of ATP6 and Bn-APX were strongly similar in the floral tissue of CMS line and the restoring line. Furthermore, in restoring line, the expression of Bn-APX is higher in the flower than that in other tissues.