Cloning and characterization of two new Class III peroxidase genes from Catharanthus roseus.

We report here the cloning and characterization of two new class III peroxidase genes, CrPrx3 and CrPrx4 from Catharanthus roseus. The full length cDNA of CrPrx3 is 1233 bp long encoding 330 amino acid residues. The CrPrx4 cDNA contains an ORF of 1055 bp, and encodes for 318 amino acids. Hypothetical 3-D structure model of CrPrx3 and CrPrx4 detected the presence of two Ca(2+) ion binding sites at proximal and distal end, and a heme group coordinate at central position. CrPrx3 and CrPrx4 are present in single copy number in C. roseus. Confocal scanning microscopy and phylogenetic analysis showed that CrPrx3 and CrPrx4 are apoplastic in nature. Phylogenetic analysis revealed that both genes have diverse expression patterns in a variety of plant tissues. Quantitative real-time PCR confirmed their maximum expression in stem tissues followed by flower tissue. The expression levels of CrPrx3 and CrPrx4 were down-regulated under salt and dehydration stress, respectively.