Cloning and characterization of peroxidase gene in Phalaenopsis

Plant peroxidases oxidize phenolic substrates at the expense of h2o2 perform a significant function in responses to environmental stresses via the regulation of h2o2 in plants. in this study,a full-length cdna encoding a peroxidase was cloned and sequenced from leaf explants of phalaenopsis by rt-pcr and race methods. the cdna designated as phpod (genbank accession no. fj161978),is 1251 bp and contains a 1041 bp open reading frame (orf),which encodes a 347 amino acid peroxidase precursor,with a 24 aa n-terminal signal peptide targeting to ndoplasmic reticulum. the putative protein has a calculated molecular weight of 37.22 kda and a calculated pi of 7.55. sequence analysis showed that the deduced amino acid sequence of phpod shares high identity with the reported pod protein sequences in database and is a typical class iii of pod family in plants. phpod possesses all active residues and two ca2+ -binging sites present in peroxidase isoenzymes c,as well as six n-glycosylation sites. semi-quantitative rt-pcr revealed that the expression of phpod was increased just before explant browning,and decreased with the aggravating of explants browning. these results indicate a possible function of phpod and provide an alternative way for controlling explant browning in tissue culture.